JP2007239649A - Internal combustion engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce noise in the outside when a plurality of compressors are arranged in parallel. <P>SOLUTION: This internal combustion engine with the supercharger is provided with the plurality of compressors arranged in parallel on the downstream side of a branching position in an intake passage and a compressor control means for controlling at least one of the plurality of compressors so as to negate the noises generated from these compressors mutually. Since at least one of the plurality of compressors is controlled so as to drown out the noises generated from the plurality of compressors arranged in parallel mutually, the noise to be released to the outside is effectively reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a supercharged internal combustion engine, and more particularly to a technique for reducing external noise when a supercharger compressor is provided in parallel.

  A turbocharger (turbocharger) is generally used as a supercharger for a vehicle mounted on an automobile, and this turbocharger drives a turbine by using the energy of exhaust gas discharged from an engine. A compressor connected coaxially with the turbine is driven to compress or supercharge intake air. In addition, as a turbocharger for vehicles, a mechanical supercharger (supercharger) that supercharges intake air by operating the compressor with the driving force from the crankshaft, or a compressor with the driving force from the electric motor There is also an electric supercharger that supercharges intake air.

  On the other hand, it is also known that the intake passage is branched and a plurality of compressors are provided in parallel on the downstream side of the branch position (see, for example, Patent Documents 1 and 2).

Japanese Utility Model Publication No. 3-68528 Japanese Patent Laid-Open No. 7-19060

  By the way, when the impeller rotates in the compressor, the impeller blades move across the air flow to generate a pressure field in which the pressure alternately increases and decreases in the circumferential direction of the impeller. It is known that noise is generated. Since this noise propagates upstream from the compressor in the intake passage and is released to the outside through the air cleaner, it becomes a problem both inside and outside the vehicle.

  In the case where a plurality of compressors are provided in parallel in the intake passage, there is a concern that noise generated from the compressors overlaps and increases, and external noise increases.

  Therefore, the present invention has been made in view of such problems, and an object thereof is to provide a supercharged internal combustion engine that can reduce external noise when a plurality of compressors are provided in parallel. is there.

  In order to achieve the above object, an internal combustion engine with a supercharger according to an aspect of the present invention includes a plurality of compressors provided in parallel on the downstream side of a branch position of an intake passage, and noise generated from these compressors. And compressor control means for controlling at least one of the plurality of compressors so as to cancel each other.

  According to this aspect of the present invention, the compressor control means controls at least one of the plurality of compressors so as to cancel each other the noises emitted from the plurality of compressors provided in parallel. Noise is effectively reduced.

  Preferably, the compressor control means controls at least one of the plurality of compressors so that noises emitted from the plurality of compressors cancel each other out at the branch position.

  Each noise generated in each compressor and propagated upstream is overlapped at the branch position of the intake passage and then released to the outside. Therefore, as in this preferred embodiment, the noise emitted to the outside is effectively reduced by controlling at least one of the plurality of compressors so that the noises emitted from the plurality of compressors cancel each other out at the branch position. Can do.

  Preferably, the apparatus further includes speed detection means for detecting rotation speeds of the plurality of compressors, and the compressor control means has the same rotation speed as the rotation speeds of the plurality of compressors detected by the speed detection means. And controlling the rotational speed of the at least one compressor.

  When a plurality of compressors are provided in parallel, these compressors are often set to substantially the same specifications. Therefore, by controlling the rotation speed of at least one compressor so that the rotation speeds of the plurality of compressors become the same rotation speed, it is possible to control the compressor so as to cancel each other noise generated from the plurality of compressors. It becomes easy.

  Preferably, the apparatus further comprises phase detection means for detecting rotational phases of the plurality of compressors, and the compressor control means is configured such that a phase difference between rotational phases of the plurality of compressors detected by the phase detection means is The rotational phase of the at least one compressor is controlled so as to coincide with a predetermined phase difference set so as to cancel noises emitted from the plurality of compressors. Thereby, the noises emitted from the plurality of compressors are canceled each other, and external noise can be effectively reduced.

  According to the present invention, an excellent effect that external noise when a plurality of compressors are provided in parallel can be reduced is exhibited.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 shows an internal combustion engine with a supercharger according to an embodiment of the present invention. The internal combustion engine, that is, the engine is an automobile multi-cylinder engine (number of cylinders Z, where Z is an even number), and may be a spark ignition engine such as a gasoline engine, or a compression ignition engine such as a diesel engine. Also good. The engine includes an engine main body 10 including a cylinder block and a cylinder head, and an intake passage 12 connected to the engine main body 10 and including an intake pipe. An air cleaner 14 is disposed at the upstream end of the intake passage 12. The intake passage 12 is branched into a plurality (two in this embodiment) on the way, and a first intake passage 12A and a second intake passage 12B are formed on the downstream side of the branch position 16. All the cylinders are divided into two cylinder groups each having a half, and the first intake passage 12A and the second intake passage 12B are connected to the respective cylinder groups to supply intake air to the respective cylinder groups. A first exhaust passage 18A and a second exhaust passage 18B are also connected to each cylinder group, and the exhaust gas of each cylinder group is discharged through the first exhaust passage 18A and the second exhaust passage 18B.

  The engine of the present embodiment is configured as a so-called parallel twin turbo engine that includes a plurality of superchargers in parallel, and in particular includes two turbochargers in parallel. A first turbocharger 20A and a second turbocharger 20B are provided corresponding to the first intake passage 12A and the first exhaust passage 18A, and the second intake passage 12B and the second exhaust passage 18B, respectively. The first turbocharger 20A and the second turbocharger 20B have substantially the same configuration or specification. The first turbocharger 20A is coaxially connected to the first radial compressor (first compressor) 22A provided in the first intake passage 12A and the first compressor 22A provided in the first exhaust passage 18A. The first turbine 24A is a radial type. The second turbocharger 20B is coaxially connected to the second radial compressor (second compressor) 22B provided in the second intake passage 12B and the second compressor 22B provided in the second exhaust passage 18B. And a radial second turbine 24B.

  In the first intake passage 12A, a first intercooler 26A is provided on the downstream side of the first compressor 22A. In the second intake passage 12B, a second intercooler 26B is provided on the downstream side of the second compressor 22B.

  The engine is provided with an electronic control unit (hereinafter referred to as ECU) 100 as control means for controlling the entire engine. The first turbocharger 20A and the second turbocharger 20B are provided with a first phase sensor 28A and a second phase sensor 28B, respectively, for detecting the rotational phase of the impeller of the corresponding compressor. Yes. Any phase sensor can be used. For example, a polygonal nut or a toothed ring is coaxially attached to the turbine shaft to which the compressor impeller is attached, and the non-contact sensor detects the passage of the convex part or tooth of the polygonal nut or toothed ring when the impeller rotates. However, it is possible to use a phase sensor that continuously generates output pulses from the non-contact sensor for each passage. Alternatively, it is possible to use a phase sensor that installs a gap sensor on the shroud wall outside the compressor impeller and continuously generates output pulses from the gap sensor every time the impeller blades pass. Furthermore, it is also possible to use a phase sensor that cuts out a part of the turbine shaft and detects the passage of the cut-out portion with a non-contact sensor.

  Based on the output signals (output pulses) of the first phase sensor 28A and the second phase sensor 28B, the ECU 100 detects the rotational phases of the first compressor 22A and the second compressor 22B. Further, the ECU 100 calculates the rotational speeds of the first compressor 22A and the second compressor 22B based on the output signals of the first phase sensor 28A and the second phase sensor 28B. In this manner, the ECU 100, the first phase sensor 28A, and the second phase sensor 28B constitute speed detection means and phase detection means.

  Further, the engine is provided with compressor control means for controlling the first compressor 22A and the second compressor 22B. More specifically, the first transmission device 30A and the second transmission device 30B are provided in the first turbine 24A and the second turbine 24B. The first transmission device 30A and the second transmission device 30B have substantially the same configuration or specification. The first transmission device 30A and the second transmission device 30B change the rotational speeds of the first turbine 24A and the second turbine 24B, and thereby change the rotational speeds of the first compressor 22A and the second compressor 22B. The first transmission device 30A and the second transmission device 30B in the present embodiment are variable nozzle types, that is, a large number of movable nozzle vanes provided at the inlet portion of the turbine impeller and the opening degree of these movable nozzle vanes. An actuator. The ECU 100 controls the actuator, and thereby controls the movable nozzle vane opening and thus the turbine flow rate. The rotational speeds of the first turbine 24A and the second turbine 24B, and thus the first compressor 22A and the second compressor 22B, are increased / decreased in accordance with the decrease / increase in the movable nozzle vane opening.

  For example, if the rotational speed of the first compressor 22A is increased once and decelerated to the original speed again, the rotational phase of the first compressor 22A can be changed while maintaining substantially the same rotational speed. Thus, the ECU 100, the first transmission device 30A, and the second transmission device 30B constitute compressor control means, and the rotation speed and rotation phase of the first compressor 22A and the second compressor 22B are controlled by the compressor control means.

  The first transmission device 30A and the second transmission device 30B of the present embodiment can increase / decrease the compressor rotation speed. In addition, as the first transmission device 30A and the second transmission device 30B, for example, an opening of a variable nozzle provided at an inlet portion of the turbine scroll chamber is changed by an actuator to increase or decrease the turbine rotation speed and thus the compressor rotation speed. Can be adopted. Alternatively, it is possible to employ a bypass passage that bypasses the turbine and distributes the exhaust gas, and that opens and closes the bypass passage with a bypass valve and an actuator, and changes the turbine rotational speed and thus the compressor rotational speed. In this case, however, the turbine rotational speed and thus the compressor rotational speed are only decreased, but cannot be increased.

  As described above, in the first compressor 22A and the second compressor 22B, when each impeller rotates, each blade moves across the flow of air, so that the circumferential direction of the impeller A pressure field in which the pressure increases and decreases alternately is generated, and noise is generated due to this pressure field. Then, this noise propagates from the compressor to the upstream side in the intake passage and is released to the outside through the air cleaner, resulting in a problem of external noise.

  This will be explained in more detail. During the rotation of the impeller, the airflow flowing in the axial direction with respect to the impeller crosses the blade moving in the circumferential direction at a right angle, so that the blade moves in the moving direction side surface. Has a positive pressure field and a negative pressure field on the back. Corresponding to the positive pressure field and the negative pressure field for each blade, the same number of pressure peaks as the number of blades are generated in the circumferential direction of the impeller.

  This is illustrated in the pressure lob pattern shown in FIG. For reference, the compressor impeller 32 and a plurality (six in the illustrated example) of blades 34 are simply shown. The diagram J shown in the figure shows the pressure field that can be generated around the impeller 32 when viewed from the upstream side in the axial direction of the impeller 32, and the pressure value increases from the center O of the impeller 32 to the radially outer side. Become. And the pressure peak P resulting from the blade | wing 34 crossing an air flow arises in the phase position of each blade | wing 34. FIG. This pressure peak P occurs at the same number of blades 34 and at the same phase position as the blades 34. During operation of the compressor, the illustrated pressure lob pattern may rotate around the center O with the impeller 32 at the same phase and the same rotational speed as the rotating impeller 32.

  As the pressure lob pattern rotates, blade passing frequency (BPF) noise (hereinafter referred to as BPF noise) is generated. This BPF noise has a peak at the frequency represented by the product F = Zb × Mc (1 / sec) of the rotational speed Mc (1 / sec) per unit time of the impeller 32 and the number of blades Zb of the impeller 32. It has noise. The noise generation position is near the entrance of the impeller 32 due to the blade shape, particularly near the front edge (leading edge) on the entrance side of the blade 34.

  The noises generated in this way in the first compressor 22A and the second compressor 22B flow backward in the first intake passage 12A and the second intake passage 12B, respectively, are synthesized at the branch position 16, and then released to the outside from the air cleaner 14. . If the phases of the two noises that overlap at the branch position 16 are the same, the two noises strengthen each other, the noise energy is doubled, and the external noise is remarkably increased. On the other hand, if the phases of the two noises that overlap at the branching position 16 are opposite, the two noises cancel each other, thereby effectively reducing the noise emitted to the outside.

  Therefore, in the present embodiment, at least one of the first compressor 22A and the second compressor 22B is controlled so as to cancel the noises generated in the first compressor 22A and the second compressor 22B in this way. More specifically, the rotational speed and the rotational phase of at least one of the first compressor 22A and the second compressor 22B are controlled so as to cancel the noises generated by the first compressor 22A and the second compressor 22B.

  FIG. 3 shows a routine for such noise reduction control. This routine is repeatedly executed by the ECU 100 at a predetermined time period or crank angle period.

  First, in step S101, the ECU 100 detects the rotational phases θc1 and θc2 and the rotational speeds Nc1 and Nc2 of the first compressor 22A and the second compressor 22B. Specifically, the ECU 100 acquires the values of the rotational phases θc1 and θc2 of the first compressor 22A and the second compressor 22B detected by the first phase sensor 28A and the second phase sensor 28B, and the rotational phases θc1, The rotational speeds Nc1 and Nc2 are calculated based on θc2, and the values are acquired.

  Next, in step S102, the ECU 100 determines whether or not the rotational speeds Nc1 and Nc2 of the first compressor 22A and the second compressor 22B are the same. If the rotational speeds Nc1 and Nc2 are not the same, the ECU 100 proceeds to step S103 and controls one or both of the first transmission 30A and the second transmission 30B so that the rotational speeds Nc1 and Nc2 are the same. Then, one or both of the rotational speeds Nc1, Nc2 of the first compressor 22A and the second compressor 22B are controlled. And this routine is complete | finished.

  On the other hand, if the ECU 100 determines that the rotational speeds Nc1 and Nc2 of the first compressor 22A and the second compressor 22B are the same in step S102, the ECU 100 proceeds to step S104 and the rotational phases θc1 and θc2 of the first compressor 22A and the second compressor 22B. Whether the rotational phase difference θd is equal to the predetermined value θd1. The predetermined value θd1 is a rotational phase difference value set so that noises emitted from the first compressor 22A and the second compressor 22B cancel each other at the branch position 16 (details will be described later). When the ECU 100 determines that the rotational phase difference θd does not match the predetermined value θd1, the ECU 100 proceeds to step S105, and the first transmission device 30A and the second transmission device so that the rotational phase difference θd matches the predetermined value θd1. One or both of 30B is controlled, and one or both of the rotational phases θc1 and θc2 of the first compressor 22A and the second compressor 22B are controlled. And this routine is complete | finished.

  When the routine is repeatedly executed in this manner, the rotational speeds Nc1 and Nc2 of the first compressor 22A and the second compressor 22B become the same eventually, and the rotational phase difference θd between the first compressor 22A and the second compressor 22B becomes a predetermined value θd1. Thus, the noises generated from the first compressor 22A and the second compressor 22B cancel each other at the branch position 16, and the external noise is effectively reduced.

  Hereinafter, the predetermined value θd1 will be described. The predetermined value θd1 is a value that can change according to the rotation speeds of the first compressor 22A and the second compressor 22B that are the same as each other (hereinafter referred to as “compressor rotation speed Nc” for convenience), and is calculated by the ECU 100 as follows. Is done.

Assuming that the first compressor 22A and the second compressor 22B are sound sources of BPF noise, noises transmitted from the first compressor 22A and the second compressor 22B (hereinafter referred to as first noise and second noise) are the first. The positions of the compressor 22A and the second compressor 22B (particularly the position of the inlet portion of the impeller) are expressed by the following equations (1) and (2), respectively.
F10 = A1 cos (a / λ × 2πt) (1)
F20 = A1 cos (a / λ × 2πt + θ) (2)

  Here, F10, F20: Wave height of the first noise and the second noise, A1: Amplitude of the first noise and the second noise, a: Sound velocity, λ: Wavelength, t: Time, θ: With respect to the first noise This is the phase difference of the second noise. Since the rotation speeds Nc1 and Nc2 of the first compressor 22A and the second compressor 22B are equal, the amplitude and wavelength of the first noise and the second noise can be made equal.

  The BPF noise is noise having a peak at a frequency represented by the product F = Zb × Mc (1 / sec) of the rotation speed Mc (1 / sec) of the impeller and the number of blades Zb of the impeller. Accordingly, when paying attention to the peak frequency F, the wavelength λ is calculated from λ = a / F. The rotational speed Mc of the impeller is calculated from the compressor rotational speed Nc, and the number of blades Zb is input to the ECU 100 in advance.

Next, assuming that the path lengths or distances from the first compressor 22A and the second compressor 22B to the branch position 16 are L1 and L2, respectively (see FIG. 1), L1 and L2 are expressed by the following equations (3) and (4), respectively. expressed.
L1 = λm + b (3)
L2 = λn + c (4)

  Here, m and n are integers, and b and c <λ. The values of L1 and L2 are geometrically determined and are input to the ECU 100 in advance. L1 and L2 may be different values. Since λ is calculated and known as described above, m, n, b, and c can be calculated naturally.

On the other hand, the wave heights F1 and F2 of the first noise and the second noise at the branch position 16 are expressed by the following equations (5) and (6).
F1 = A2 cos (a / λ × 2π (t−L1 / a)) (5)
F2 = A2cos (a / λ × 2π (t−L2 / a) + θ) (6)

  Here, compared with the equations (1) and (2), the amplitudes of the first noise and the second noise are changed from A1 to A2 (<A1). This is because the first noise and the second noise are branched. This is because the attenuation while reaching the position 16 is taken into consideration. However, it is assumed that the attenuation amounts of both noises are equal.

The expressions (5) and (6) can be transformed into the following expressions (7) and (8) using the expressions (3) and (4).
F1 = A2 cos (a / λ × 2πt−2π (m + b / λ)) (7)
F2 = A2 cos (a / λ × 2πt−2π (n + c / λ) + θ) (8)

From these equations (7) and (8),
2π (m + b / λ) -2π (n + c / λ) -θ
Is equal to (2n ′ + 1) π (where n ′ = 0, 1, 2,...), F1 and F2 cancel each other out of phase. From this, the phase difference θ is obtained by the following equation (9).
θ = 2π (mn) + 2π (bc) / λ ± (2n ′ + 1) π (9)

By the way, the phase difference θ obtained here is a more general value, and is a value when the phase is 2π, one wavelength and one period. However, in an actual impeller, there is one wavelength and one period at a phase 2π / Zb between adjacent blades of the impeller, and one wave is generated between 2π / Zb. Accordingly, the predetermined rotational phase difference θd1 is eventually expressed by the following equation (10).
θd1 = 2π / Zb × θ / 2π
= 1 / Zb (2π (mn) + 2π (bc) / λ ± (2n ′ + 1) π)
... (10)

  Note that ± may be + or-, but is + in this embodiment.

  Thus, in the step S105, the first compressor 22A and the second compressor 22B are set so that the rotational phase difference θd between the first compressor 22A and the second compressor 22B matches the predetermined value θd1 calculated from the equation (10). Any one or both of the rotational phases θc1 and θc2 of the motor are controlled. As a result, both noises generated from the first compressor 22A and the second compressor 22B cancel each other out at the branch position 16, and the external noise is effectively reduced.

  Various other embodiments of the present invention are conceivable. For example, in the present embodiment, a turbocharger compressor is shown as the compressor, but the compressor may be a mechanical supercharger or an electric supercharger compressor, for example. An embodiment in which these compressors are combined and arranged in parallel is also possible.

  The embodiment of the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

1 is a system diagram showing an internal combustion engine with a supercharger according to an embodiment of the present invention. It is a diagram which shows a pressure lob pattern. It is a flowchart which shows the routine of noise reduction control.

Explanation of symbols

12 intake passage 12A first intake passage 12B second intake passage 16 branch position 20A first turbocharger 20B second turbocharger 22A first compressor (first compressor)
22B Second compressor (second compressor)
28A First phase sensor 28B Second phase sensor 30A First transmission 30B Second transmission 100 Electronic control unit (ECU)
Nc1 Rotational speed of the first compressor Nc2 Rotational speed of the second compressor θc1 Rotational phase of the first compressor θc2 Rotational phase of the second compressor θd Rotational phase difference between the first compressor and the second compressor θd1 Predetermined value of the rotational phase difference

Claims (4)

A plurality of compressors provided in parallel downstream of the branch position of the intake passage;
An internal combustion engine with a supercharger, comprising: compressor control means for controlling at least one of the plurality of compressors so as to cancel noises generated from the compressors.   2. The turbocharger according to claim 1, wherein the compressor control unit controls at least one of the plurality of compressors so that noises emitted from the plurality of compressors cancel each other at the branch position. Internal combustion engine.   The apparatus further comprises speed detecting means for detecting the rotational speeds of the plurality of compressors, and the compressor control means is configured so that the rotational speeds of the plurality of compressors detected by the speed detecting means become the same rotational speed. The supercharged internal combustion engine according to claim 1 or 2, wherein the rotational speed of at least one compressor is controlled. The compressor further comprises phase detection means for detecting rotational phases of the plurality of compressors, wherein the compressor control means has a phase difference between rotational phases of the plurality of compressors detected by the phase detection means. The rotational phase of the at least one compressor is controlled so as to coincide with a predetermined phase difference set so as to cancel noises emitted from the machine. Internal combustion engine with a feeder.

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