JP2006194206A - Supercharging system for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supercharging system for an engine by which unnecessary power consumption is suppressed, and the engine-torque is efficiently increased. <P>SOLUTION: The supercharging system for an engine comprises an electric supercharger placed in an intake passage, a bypass for allowing communication between the upstream and the downstream of the intake passage in the electric supercharger, a bypass valve for opening/closing the bypass passage, and an intake-system controller which closes the bypass valve in a specified engine-operation range and at the same time actuates the electric supercharger. The supercharging system comprises further an acceleration valve-travel sensor, an engine-speed sensor, and an engine-control device for finding a rotational speed of the electric supercharger at which intake air-flow in response to a sensor-detected engine load and engine speed, while maintaining the power consumption of the electric supercharger nearly at a fixed value for obtaining a discharge pressure on the verge of knocking. The intake system controller controls the supercharger so as to attain a rotational speed computed by the control device in operation time of the electric supercharger. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention belongs to the technical field of an engine supercharging device that increases engine torque by supercharging.

  Conventionally, superchargers and turbochargers that supercharge intake air as means for increasing engine torque are well known. However, as a result of the supercharging ability being greatly affected by the engine speed, the supercharging pressure is low. There is a problem of shortage. On the other hand, since the electrically driven electric supercharger can control the rotational speed without being affected by the engine rotational speed, it has an advantage that a sufficient supercharging pressure can be generated even in a low rotational speed region.

For example, a supercharger described in Patent Literature 1 includes an electric supercharger disposed on an intake passage, a bypass passage communicating with the turbocharger on the downstream side, and a bypass provided on the bypass passage. And a supercharger by operating the supercharger and closing the bypass valve in a predetermined operating region of the engine.
JP 2003-227342 A

  By the way, in the supercharging device as described in Patent Document 1, the discharge pressure increases in accordance with the increase in power consumption of the electric supercharger, and the engine torque theoretically increases accordingly. Actually, as shown in FIG. 9, when the discharge pressure of the electric supercharger, that is, the power consumption exceeds a predetermined value x, knocking is likely to occur, and retard control of the ignition timing is performed to suppress this knocking. Therefore, the actually obtained engine torque is smaller than the theoretical engine torque in proportion to the power consumption of the supercharger.

  Further, as the power consumption increases, the amount of power generated by the alternator, that is, the amount of torque consumed by the alternator increases. Therefore, in the region where the power consumption is greater than or equal to the predetermined value x, the actually obtained torque is further suppressed. As a result, even if the power consumption of the turbocharger is increased in the region where the power consumption is greater than or equal to the predetermined value x, the net Actual torque hardly increases.

  SUMMARY OF THE INVENTION An object of the present invention is to suppress wasteful power consumption and increase engine torque efficiently in an engine supercharging device.

  In order to solve the above problems, the present invention is configured as follows.

  First, the invention according to claim 1 of the present application is directed to an electric supercharger provided in an intake passage, a bypass passage communicating with the downstream side of the electric supercharger in the intake passage, and opening and closing the bypass passage. An engine supercharging device provided with a bypass valve and a supercharging control means that closes the bypass valve and activates the electric supercharger in a predetermined engine operating region, and relates to the amount of air sucked into the engine Intake air amount parameter detection means for detecting a parameter, and an intake air amount corresponding to the parameter detected by the detection means while maintaining the power consumption of the electric supercharger at a substantially constant value at which a discharge pressure at the knocking limit is obtained And a supercharger rotational speed calculating means for obtaining the rotational speed of the electric supercharger that provides the supercharging control means, when the electric supercharger is activated, the supercharging control means has the rotational speed calculated by the calculating means. And controlling the turbocharger in earthenware pots. The intake air amount parameter detecting means includes a method for calculating a parameter relating to the intake air amount from the engine load and the engine speed, and a method for directly detecting the parameter of the intake air amount by a sensor or the like.

  The invention according to claim 2 is the engine supercharging device according to claim 1, wherein the supercharger rotation speed calculation means is configured to rotate the supercharger as the intake air amount corresponding to the parameter increases. It is characterized by calculating so that a number may fall.

  According to a third aspect of the present invention, in the engine supercharging device according to the first or second aspect, the knocking detecting means for detecting the occurrence of knocking, and the occurrence of knocking is detected by the knocking detecting means. Ignition timing control means for retarding the ignition timing when the ignition timing is retarded, and the supercharger rotation speed calculation means corresponds to a reduced engine torque due to the retard when the ignition timing is retarded by the ignition timing control means In order to supplement the minute, the calculation is performed so that the rotation speed of the supercharger increases.

  First, according to the first aspect of the present invention, the electric power consumption of the electric supercharger that can obtain the discharge pressure at the knocking limit is obtained in advance, and the intake air required according to the operating state while maintaining the electric power consumption. The number of revolutions of the electric supercharger is controlled so that the amount can be obtained, avoiding the use of the electric supercharger in a region where the efficiency of the engine torque obtained with respect to the power consumption decreases due to the occurrence of knocking. Therefore, wasteful power consumption is suppressed and efficient torque increase can be achieved.

  Further, as specific control according to the first aspect of the present invention, according to the second aspect of the present invention, the electric supercharging that the rotational speed decreases when the intake air amount is increased while the power consumption is kept constant. Since the rotation speed of the supercharger is calculated according to the characteristics of the machine, the effect of the invention according to claim 1 can be obtained.

  On the other hand, in spite of the above control, when the occurrence of knocking is detected, this is suppressed by retarding the ignition timing. At this time, the engine torque is reduced.

  On the other hand, according to the invention described in claim 3, since the torque equivalent reduced by the retard of the ignition timing is complemented by increasing the rotational speed of the electric supercharger, the engine is suppressed while suppressing the occurrence of knocking. A decrease in torque is avoided. At this time, since the power consumption of the electric supercharger is set to the knocking limit as in the inventions of the first and second aspects, a margin is left in the power with respect to the rated output. The speed of the machine can be increased.

  Hereinafter, embodiments of the present invention will be described.

  First, a first embodiment of the present invention will be described. FIG. 1 shows an engine intake system 1 according to the present embodiment. In this intake system 1, an air cleaner 3, an electric supercharger 4, a throttle valve 5, and a surge tank 6 are provided in the intake passage 2 from the upstream side, and each of the cylinders # 1 to # 4 is provided from the surge tank 6. A plurality of independent intake passages 7...

  In addition, a bypass passage 8 that directly communicates the upstream side and the downstream side of the electric supercharger 4 in the intake passage 2 is provided, and a bypass valve that controls the flow rate of air passing through the passage 8 is provided in the bypass passage 8. 9 is provided.

  The electric supercharger 4 includes a compressor 4a and a motor 4b. When the motor 4b is driven, the compressor 4a sucks air and pumps it to the cylinders # 1 to # 4, thereby filling the air amount or engine torque. Increase. In the following description, the rotational speed of the electric supercharger 4 is the rotational speed of the motor 4b.

  Further, an engine control device 100 for controlling the engine is provided, and a signal from the accelerator opening sensor 10 for detecting the amount of depression of the accelerator pedal 10a (engine load) by the driver and the engine speed are controlled by the control device 100. A signal from the engine speed sensor 11 to be detected, a signal from the intake air temperature sensor 12 to detect the intake air temperature, a signal from the knocking sensor 13 to detect the occurrence of knocking, and the like are input.

  The throttle actuator 14 that opens and closes the throttle valve 6 based on these input signals, the spark plugs 15... 15 provided in the cylinders # 1 to # 4, and the intake system controller 101 that controls the intake system 1 Output a control signal. Further, the intake system controller 101 outputs a control signal to the bypass actuator 16 that opens and closes the bypass valve 9, the electric supercharger controller 102 that controls the rotational speed of the electric supercharger 4, and the like.

  The intake passage 2, the electric supercharger 4, the bypass passage 8, and the bypass valve 9 correspond to the constituent elements that are the premise of the supercharging device according to claim 1.

  Further, the engine is provided with an alternator 20 that generates electric power by driving the engine, and a battery 21 that stores electric power generated by the alternator 20, and electric power is supplied from the battery 21 to the electric supercharger controller 102. It comes to be supplied.

  The accelerator opening sensor 10 and the engine speed sensor 11 correspond to the intake air amount parameter detecting means in the supercharging device according to claim 1, and the intake system controller 101 is in the supercharging device according to claim 1. This corresponds to supercharger control means. Further, the engine control device 100 corresponds to a supercharger rotation speed calculating means in the supercharging device according to claim 1 and an ignition timing control means in the supercharging device according to claim 3, and the knocking sensor 13 is claimed in claim 3. It corresponds to the knocking detection means in the supercharging device described in 1.

On the other hand, the engine control apparatus 100 stores a map in which the engine operating region shown in FIG. 2 is set. In this map, four areas with the engine speed and the engine load as parameters are set. That is, on the high speed side (the engine speed is N1 or more), a natural intake region where the electric supercharger 4 does not operate with the bypass valve 9 opened is set. In this natural intake region, the air introduced into the intake passage 2 flows through the bypass passage 8 as shown by an arrow A in FIG.
Further, a pre-rotation preload region in which the electric supercharger 4 operates with the bypass valve 9 closed is set on the low load low rotation side (the engine speed is N1 or more and the engine load is α1 or less). ing. On the high load low rotation side (the engine speed is N1 or less and the engine load is α1 or more), a supercharging region for operating the electric supercharger 4 with the bypass valve 9 closed is set. A surging region in which the electric supercharger 4 is operated with the bypass valve 9 in a half-open state is set on the low rotation side in the region.

  In the pre-rotation pre-load area, the pressure on the downstream side of the electric supercharger 4 in the intake passage 2 is increased in advance, thereby improving the responsiveness of the super-charging pressure when the operation area shifts to the super-charging area. At this time, the throttle control of the throttle valve 6 is performed at the same time so that the intake air amount introduced into the cylinders # 1 to # 4 is not increased more than necessary.

  In the supercharging region, the air introduced into the intake passage 2 flows through the intake passage 2 as shown by an arrow B in FIG. The surging region is a region where the intake air may flow backward through the electric supercharger 4 when the pressure on the downstream side of the electric supercharger 4 is high and the flow rate of the intake air is small. By partially opening 9, a part of the intake air is circulated in the bypass passage 8 as shown by an arrow C in FIG.

  On the other hand, the map of FIG. 3 shows the characteristics of the electric supercharger 4. According to this, the vertical and vertical pressure ratios of the electric supercharger 4 with respect to the intake air amount on the horizontal axis are plotted on the vertical axis. It shows. And the area | region X shown to a figure is set as a use area | region of this electric supercharger 4. FIG. The region Y on the low intake air amount / high pressure ratio side of the region X is a region where the surging occurs because the pressure on the downstream side of the electric supercharger 4 is high and the air flow rate is small.

  Further, in the area X, areas a to p corresponding to the power consumption of the electric supercharger 4 are set. These areas a to p are substantially strip-shaped areas divided by a plurality of curves whose pressure ratio decreases as the intake air amount increases, and the power consumption increases in the order of ap.

  Further, in region X, the characteristics of the rotational speed of the electric supercharger 4 are shown. In this characteristic, a curve with a rotational speed of 40000 rpm is set on the lower left side of the region X, the rotational speed increases as it moves in the upper right direction, and a curve with a rotational speed of 80000 rpm is set on the upper right side of the region X.

  By the way, as described with reference to FIG. 9, when the electric power consumption of the electric supercharger exceeds a certain value x, knocking is likely to occur due to an increase in the discharge pressure corresponding to this, in order to suppress this knocking. Since the retard control of the ignition timing is performed, the actually obtained engine torque is moderately increased. Further, since the torque consumed by the alternator 20 increases in accordance with the power consumption of the electric supercharger 4, the actually obtained torque is further suppressed. As a result, the power consumption of the supercharger 4 is excessive in the region where x is greater than x. Even if the power consumption of the feeder 4 is further increased, the net actual torque hardly increases.

  The intake system 1 is controlled by the engine control device 100, the intake system controller 101, and the electric supercharger controller 102 according to the flowchart shown in FIG.

  In the following description, it is assumed that the power consumption (x) of the electric supercharger 4 when the aforementioned knocking is likely to occur is 1 kW, which is half of the rated power.

  First, in step S1, the engine control apparatus 100 reads various signals from each sensor and obtains the intake air amount based on these signals. Specifically, the intake air amount is calculated based on the engine load detected by the accelerator opening sensor 10 and the engine speed detected by the engine speed sensor 11. At this time, the intake air amount may be detected by a sensor or the like.

  Then, in step S2, it is determined whether or not the engine speed is greater than N1, and when it is greater than N1, it is in the natural intake region, so the process proceeds to step S3 to stop the electric supercharger 4 and in step S4. The bypass valve 9 is fully opened. As a result, the natural intake in which the air introduced from the air cleaner 3 is supplied to the cylinders # 1 to # 4 via the bypass passage 8 is executed.

  On the other hand, when the engine speed is N1 or less in step S2, the process proceeds to step S5 to determine whether the engine load is α1 or more. When the engine load is greater than α1, the operation region is a supercharging region, and it is determined in step S6 whether the operation region is a surging region.

  When the operation region is not the surging region in step S6, the process proceeds to step S7, the bypass valve 9 is closed, and 1 kW operation control is performed in step S8. In the 1 kW operation control, the supercharger 4 in which the intake air amount obtained in step S1 is obtained on the region h corresponding to 1 kW among the power consumption regions a to p of the electric supercharger 4 shown in FIG. The rotation speed of the supercharger 4 is controlled to this rotation speed.

For example, in the 1 kW operation control when the intake air amount obtained in step S1 is 2 m ³ / min, the rotational speed of the electric supercharger 4 at the point Z on the region h is read in the map of FIG. The point Z is at a position where the rotational speed is slightly closer to 60000 rpm from 60000 rpm, and 62000 rpm is obtained by interpolation. Then, the engine control device 100 sends a signal to the electric supercharger controller 102 via the intake system controller 101 to control the supercharger 4 to have this rotational speed, whereby the power consumption is 1 kW and the rotational speed is Operation of 62000 rpm is realized.

  The 1 kW operation control in step S8 corresponds to the gist of the inventions described in claims 1 and 2.

  Next, it progresses to step S9 and it is determined whether the knocking sensor 13 has knocked. When the occurrence of knocking is not detected, the 1 kW operation control is continued as it is. When the occurrence of knocking is detected, the process proceeds to step S10, and the engine control device 100 sets the ignition timing to each spark plug 15 ... 15. A signal for retarding is sent to execute ignition timing retard.

  In step S11, the number of revolutions of the electric supercharger 4 is increased in accordance with the amount of decrease in engine torque due to the ignition timing retard. At this time, the increase amount of the supercharger rotational speed is set according to various knocking occurrence factors such as the intake air temperature detected by the intake air temperature sensor 12 and the octane number of the used fuel. For example, as shown in FIG. 5, the higher the intake air temperature, the easier the knocking occurs, and the engine torque decrease due to the retard of the ignition timing is correspondingly larger. Therefore, in order to compensate for this, the rotational speed of the supercharger 4 is increased. Try to increase. Similarly, as shown in FIG. 6, the lower the octane number of the fuel used, the greater the number of revolutions of the supercharger 4 is increased.

  This step S11 corresponds to the gist of the invention described in claim 3.

On the other hand, when the operation region is the surging region in step S6, the process proceeds to step S12, the bypass valve 9 is half-opened, and the aforementioned 1 kW operation control is performed in step S13. As a result, a part of the air discharged from the electric supercharger 4 flows back through the bypass passage 8, and as a result, the pressure downstream of the supercharger 4 is lowered and surging is avoided. Further, since a part of the air is circulated in this way, the amount of air actually sucked becomes smaller than that required. On the other hand, if the amount of air circulating through the bypass passage 8 is β, it is assumed that the intake air amount increased by the amount corresponding to β is required in order to supplement the air amount β during the 1 kW operation control. Will apply the map. For example, when the intake air amount calculated in step S1 is 2 m ³ / min, 2 + βm ³ / min obtained by adding the amount of air to be circulated 2 + βm ³ / min is set as the value of the intake air amount and the region h corresponding to this intake air amount The rotational speed (about 58000 rpm) at the point Z ′ is read out.

  By the way, when the engine load is α1 or less in step S5, since the operation region is the pre-rotation preload region, control is performed so that the bypass valve 9 is almost closed in step S14, and rotation of the electric supercharger 4 is performed in step S15. The number is controlled to a preset rotation number for pre-rotation preload control, and the process proceeds to step S9. The rotational speed of the electric supercharger 4 in the pre-rotation preload area is set to be lower than that in the supercharge area, for example.

  Next, as a second embodiment of the present invention, the case where the operation region shown in the map shown in FIG. 7 is set will be described. This map is obtained by changing the pre-rotation preload area set in the low-load low-rotation area of the map of FIG. 2 to the pre-rotation area.

  In the pre-rotation control performed in this pre-rotation region, the supercharging pressure when the electric supercharger 4 is operated with the bypass valve 9 opened and the air is circulated through the bypass passage 8 and is transferred to the super-charging region. Improve responsiveness. In the pre-rotation region, the bypass valve 9 is in an open state, so that pre-loading is not performed.

  In this embodiment, the intake system 1 is controlled according to the flowchart shown in FIG. In this flowchart, steps S21 to S33 are the same controls as steps S1 to S13 of FIG. 5 in the first embodiment, and thus description thereof is omitted. Here, step S34 related to the pre-rotation control is omitted. Only S35 will be described.

  That is, in step S34, the bypass valve 9 is controlled to be fully opened, and in step S35, the rotation speed of the electric supercharger 4 is controlled to a preset rotation speed for pre-rotation control.

  As described above, the electric power of the electric supercharger 4 that can obtain the discharge pressure at the knocking limit in advance is obtained as 1 kW, and the electric supercharger is obtained so as to obtain a predetermined intake air amount while maintaining this electric power consumption 1 kW. Since the rotation speed of the charger 4 is controlled, it is avoided that the electric supercharger is used in a region where the efficiency of the engine torque obtained with respect to the power consumption is reduced (1 kW or more), and therefore, wasteful power consumption. Is suppressed, and an efficient torque increase can be achieved.

  Further, as a specific control, as shown in FIG. 3, according to the characteristics of the electric supercharger 4 that the rotational speed decreases when the intake air amount is increased while maintaining the power consumption of the electric supercharger 4 at 1 kW. By calculating the rotational speed of the supercharger 4, the above-described effect can be obtained.

  On the other hand, in spite of such control, when the occurrence of knocking is detected, this is suppressed by retarding the ignition timing, but at this time, the engine torque decreases.

  On the other hand, a decrease in the engine torque is avoided by supplementing the torque equivalent decreased by the retard of the ignition timing by increasing the rotation speed of the electric supercharger 4. Moreover, since a margin is left in the electric power with respect to the rated output of the electric supercharger 4 by the 1 kW operation, the rotational speed of the supercharger 4 can be increased in this way.

  An object of the present invention is to suppress wasteful power consumption and efficiently increase torque in an engine supercharging device. INDUSTRIAL APPLICABILITY The present invention is widely suitable for the technical field of an engine supercharging device that increases engine torque by supercharging.

1 is an engine intake system according to an embodiment of the present invention. It is a map which shows the driving | operation area | region of an engine. It is a map which shows the characteristic of an electric supercharger. It is a flowchart which concerns on control of the system of an intake system. It is a map for determining the rotation speed increase amount of the electric supercharger according to the intake air temperature. It is a map for determining the rotation speed increase amount of the electric supercharger according to the octane number. It is a map which shows the driving | operation area | region of the engine which concerns on the 2nd Embodiment of this invention. It is a flowchart which concerns on control of the system of the same intake system. It is a map which shows the increase characteristic of the engine torque with respect to the power consumption of a supercharger.

Explanation of symbols

2 Intake Passage 4 Electric Supercharger 8 Bypass Passage 9 Bypass Valve 10 Accelerator Opening Sensor 11 Engine Speed Sensor 13 Knock Sensor 100 Engine Control Device 101 Intake System Controller

Claims (3)

An electric supercharger provided in the intake passage; a bypass passage communicating the upstream and downstream sides of the electric supercharger in the intake passage; a bypass valve opening and closing the bypass passage; and the bypass in a predetermined engine operating region An engine supercharging device comprising a supercharging control means for closing an valve and operating an electric supercharger,
Intake air amount parameter detection means for detecting a parameter relating to the amount of air taken into the engine;
While maintaining the electric power consumption of the electric supercharger at a substantially constant value at which the discharge pressure at the knocking limit is obtained, the rotational speed of the electric supercharger that obtains the intake air amount according to the parameter detected by the detection means is obtained. And a supercharger rotation speed calculation means,
The supercharger for an engine is characterized in that the supercharging control means controls the supercharger so that the rotational speed calculated by the calculating means is obtained when the electric supercharger is operated. The engine supercharging device according to claim 1,
The supercharger rotational speed calculation means performs calculation so that the rotational speed of the supercharger decreases as the intake air amount corresponding to the parameter increases. The supercharger for an engine according to claim 1 or 2,
Knocking detection means for detecting occurrence of knocking;
Ignition timing control means for retarding the ignition timing when occurrence of knocking is detected by the knocking detection means,
When the ignition timing is retarded by the ignition timing control means, the supercharger rotation speed calculation means is arranged so that the rotation speed of the supercharger increases in order to compensate for the reduced engine torque equivalent due to the retard. A supercharging device for an engine characterized by calculating.

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