JP2008002275A - Supercharging system for internal combustion engines - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve stability of a turbocharger when auxiliary air is supplied. <P>SOLUTION: As illustrated in figure 1, a supercharging system for an internal combustion engine comprises a supercharger having a turbine 11, a pressure accumulation tank 21 for supplying auxiliary air to the turbine, an adjusting means 25 for adjusting a flow rate of the auxiliary air supplied from the pressure accumulation tank to the turbine, a first control means 30 for controlling the adjusting means so that the flow rate of the auxiliary air becomes the maximum flow rate until the number of rotation of the turbine becomes the number of initial target rotation which is N times of the number of first target rotation (here, 0<N<1), and a second control means 30 for controlling the adjusting means so that the number of rotation of the turbine has a value which is the number of first target rotation or less and the number of initial target rotation or more, and the number of rotation of the turbine becomes the number of second target rotation converging on the number of first target rotation and indicated by a target function after passing the designated time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technical field of a supercharging system for an internal combustion engine such as a turbocharger mounted on an engine, for example.

  For the purpose of improving engine output, a technique for installing a turbocharger (supercharger) in the engine is known. Furthermore, in order to improve the responsiveness of the turbocharger, in addition to the exhaust gas supplied from the exhaust manifold, the auxiliary air stored in the pressure accumulation tank is supplied to the exhaust gas of the turbocharger. A technique is known in which unburned components are combusted to raise the exhaust gas temperature and increase the flow rate of the exhaust gas, thereby increasing the rotational speed of the exhaust turbine (see Patent Documents 1 to 4). In particular, the supply amount of auxiliary air is adjusted so that the rotational speed of the exhaust turbine becomes the target rotational speed (see Patent Document 3, etc.).

  Patent Document 5 discloses a technique for making the target rotational speed of the supercharging pressure smaller than the original target rotational speed in order to prevent overshooting of the supercharging pressure.

Japanese Utility Model Publication No. 56-169422 Japanese Utility Model Publication No. 58-152522 Japanese Utility Model Publication No. 58-144030 Japanese Patent Laid-Open No. 62-276221 Japanese Patent Laid-Open No. 3-210023

  By the way, when the diameter when the valve is opened is relatively large, a large amount of auxiliary air is supplied (that is, sprayed) to the exhaust turbine in a short time, so that the rotational speed of the exhaust turbine increases rapidly. As a result, the rotational speed of the exhaust turbine becomes excessively large. Furthermore, since the consumption amount of auxiliary air is large, the energy for increasing the rotational speed of the exhaust turbine decreases with the passage of time, and as a result, the rotational speed of the exhaust turbine decreases. That is, it becomes difficult or impossible to stabilize the rotational speed of the exhaust turbine or to smoothly increase it to the steady rotational speed, resulting in a technical problem that the transient performance of the turbocharger deteriorates. On the other hand, when the diameter when the valve is opened is relatively small, the energy for increasing the rotational speed of the exhaust turbine is small, resulting in a technical problem that turbo lag occurs.

  The present invention has been made in view of, for example, the above-described conventional problems, and provides a supercharging system for an internal combustion engine that can improve the stability of a turbocharger, for example, when supplying auxiliary air. The task is to do.

  The supercharging system for an internal combustion engine of the present invention includes a supercharger including an exhaust turbine, a pressure accumulation tank that supplies auxiliary air to the exhaust turbine, and a flow rate of the auxiliary air that is supplied from the pressure accumulation tank to the exhaust turbine. The flow rate of the auxiliary air becomes a maximum flow rate until the rotation speed of the exhaust turbine reaches an initial target rotation speed that is N times the first target rotation speed (where 0 <N <1). First control means for controlling the adjusting means, and after the rotational speed of the exhaust turbine exceeds the first target rotational speed, the rotational speed of the exhaust turbine is equal to or less than the first target rotational speed and the initial The adjusting means controls the adjusting means so as to follow a second target speed indicated by a target function that has a value equal to or higher than the target speed and converges to the first target speed after a predetermined time has elapsed. With 2 control means That.

  According to the supercharging system for an internal combustion engine of the present invention, the exhaust gas discharged from the internal combustion engine rotates the exhaust turbine, and the compressor connected to the exhaust turbine compresses the intake air accordingly. By supplying this compressed intake air to the internal combustion engine, the output of the internal combustion engine can be improved. Furthermore, in addition to the exhaust gas, auxiliary air (for example, compressed air) is supplied (in other words, blown) from the pressure accumulation tank to the exhaust turbine, so that the rotation of the exhaust turbine can be further promoted. The time lag of the turbine (that is, the turbo lag) can be improved and the intake pressure can be increased. At this time, the flow rate of the auxiliary air is adjusted by adjusting means such as a solenoid valve.

  Particularly in the present invention, when the vehicle starts accelerating, first, under the control of the first control means, until the rotational speed of the exhaust turbine reaches an initial target rotational speed that is N times the first target rotational speed. The adjusting means adjusts the flow rate of the auxiliary air so that the flow rate of the auxiliary air becomes the maximum flow rate. After the rotational speed of the exhaust turbine reaches the initial target rotational speed, the second rotational speed of the exhaust turbine is indicated by a target function under the control of the second control means instead of the control of the first control means. The adjusting means adjusts the flow rate of the auxiliary air so as to follow the target rotational speed. The target function is a function that has a value equal to or lower than the first target rotational speed and equal to or higher than the initial target rotational speed, and converges to the first target rotational speed after a predetermined time has elapsed (more preferably, converges smoothly). . Specifically, for example, the target function is a function whose initial value is the initial target rotational speed and whose final value is the first target rotational speed, and between the initial target rotational speed and the first target rotational speed. A function obtained by connecting with a curve specified by using various mathematical methods, statistical methods or theoretical methods. That is, the second control unit controls the adjustment of the flow rate of the auxiliary air by the adjusting unit so that the rotation number follows the second target rotation number while monitoring the rotation number of the exhaust turbine (for example, feedback control). To do.

  As a result, the flow rate of the auxiliary air at the initial stage of acceleration is not reduced unnecessarily, and the turbo lag immediately after the start of acceleration of the vehicle can be improved. Further, after a while after the acceleration of the vehicle is started, the flow rate of the auxiliary air so that the rotational speed of the exhaust turbine follows a second target rotational speed that is smaller than the first target rotational speed that is the original target rotational speed. Therefore, there is little or no risk that the rotational speed of the exhaust turbine excessively increases (that is, overshoots). Nevertheless, since the second target rotational speed is specified by a target function that converges to the first target rotational speed, the rotational speed of the exhaust turbine can be increased naturally (in other words, smoothly). For this reason, while being able to increase the rotation speed of an exhaust turbine smoothly or stably, the problem which the rotation speed of an exhaust turbine overshoots can be prevented suitably. In other words, the stability of the supercharging system for an internal combustion engine can be improved.

  In one aspect of the supercharging system for an internal combustion engine of the present invention, the initial target rotational speed is 0.7 times or 0.9 times the first target rotational speed.

  According to this aspect, in the early stage of acceleration, the flow rate of the auxiliary air is set to the maximum flow rate until the rotation speed of the exhaust turbine becomes 0.7 times or 0.9 times the first target rotation speed. Since the flow rate of the auxiliary air is adjusted, it is possible to improve the turbo lag immediately after the acceleration of the vehicle is started.

  In another aspect of the supercharging system for an internal combustion engine of the present invention, the first target rotational speed is a steady rotational speed of the exhaust turbine when the auxiliary air is not supplied.

  According to this aspect, the flow rate of the auxiliary air can be adjusted so that the rotational speed of the exhaust turbine eventually becomes a steady rotational speed, and therefore the rotational speed of the exhaust turbine can be increased smoothly or stably. In addition, the rotational speed of the exhaust turbine can be stabilized.

  In another aspect of the supercharging system for an internal combustion engine according to the present invention, the second control means may control the flow rate of the auxiliary air when the rotational speed of the exhaust turbine becomes equal to or lower than the second target rotational speed. (Or the flow rate of the auxiliary air is set to the maximum flow rate), and when the rotational speed of the exhaust turbine becomes equal to or higher than the second target rotational speed, the flow rate of the auxiliary air is relatively decreased ( Alternatively, the adjusting means is controlled so that the flow rate of the auxiliary air is set to zero.

  According to this aspect, when the rotational speed of the exhaust turbine becomes equal to or lower than the second target rotational speed, it can be determined that the flow rate of the auxiliary air supplied to the exhaust turbine is insufficient. That is, it can be determined that the flow rate of the auxiliary air supplied to the exhaust turbine needs to be increased from the current flow rate in order to make the exhaust turbine rotation speed follow the second target rotation speed. For this reason, in this case, the flow rate of the auxiliary air is relatively increased. On the other hand, when the rotational speed of the exhaust turbine is equal to or higher than the second target rotational speed, it can be determined that the flow rate of the auxiliary air supplied to the exhaust turbine is excessive. That is, it is possible to determine that the flow rate of the auxiliary air supplied to the exhaust turbine needs to be reduced from the current flow rate in order to make the exhaust turbine rotation speed follow the second target rotation speed. For this reason, in this case, the flow rate of the auxiliary air is relatively decreased. Thereby, the flow rate of the auxiliary air can be suitably adjusted so that the rotational speed of the exhaust turbine follows the second target rotational speed, and as a result, the rotational speed of the exhaust turbine can be increased smoothly or stably. In addition, the inconvenience of overshooting the rotational speed of the exhaust turbine can be suitably prevented.

  The operation and other advantages of the present invention will become more apparent from the embodiments described below.

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

(1) Basic Configuration First, a basic configuration of an embodiment according to a supercharging system for an internal combustion engine of the present invention will be described with reference to FIG. FIG. 1 is a block diagram conceptually showing the basic structure of the embodiment relating to the supercharging system for an internal combustion engine according to this embodiment.

  As shown in FIG. 1, the internal combustion engine supercharging system according to the present embodiment includes, for example, an exhaust exhaust turbine 11, a compressor 12, a rotor shaft 13, an air cleaner 14, an intercooler 15, an accumulator tank 21, a check valve 22, An auxiliary compressed air pipe 23, an auxiliary compressed air supply device 24, a flow rate adjusting electromagnetic valve 25, an air assist pipe 26, an ECU (Electric Control Unit) 30, and the like are configured.

  High pressure exhaust gas discharged from the cylinder 2 of the engine 1 is sprayed to the exhaust exhaust turbine 11 via the exhaust manifold 3. The exhaust turbine 11 is rotated by the exhaust gas. As the exhaust turbine 11 rotates, the compressor 12 connected to the exhaust turbine 11 via the rotor shaft 13 also rotates in the same manner. At this time, the intake air supplied to the compressor 12 via the air cleaner 14 is compressed by the rotation of the compressor 12, and then passes through the intercooler 15 to lower its temperature. Thereafter, the compressed intake air is supplied into the cylinder 2 of the engine 1 through the intake manifold 4.

  Thereby, since a large amount of air can be supplied into the cylinder 2 of the engine 1, the output of the engine 1 can be improved.

  Furthermore, in the supercharging system for an internal combustion engine according to the present embodiment, auxiliary compressed air (accumulated in the accumulator tank 21) is added to the exhaust turbine 11 in addition to the high-pressure exhaust gas discharged from the cylinder 2 of the engine 1. Auxiliary compressed air) is sprayed.

  Specifically, the auxiliary compressed air is generated by the operation of the auxiliary compressed air supply device 24 including, for example, a pump. The generated auxiliary compressed air is accumulated in the pressure accumulating tank 21 via the auxiliary compressed air pipe 23. At this time, in order to prevent the auxiliary compressed air accumulated in the pressure accumulating tank 21 from flowing back to the auxiliary compressed air supply device 24, the auxiliary compressed air pipe 23 has an auxiliary only from the auxiliary compressed air supply device 24 to the pressure accumulating tank 21 side. A check valve 22 is provided that allows compressed air to flow.

  The auxiliary compressed air accumulated in the pressure accumulating tank 21 is sprayed to the exhaust turbine 11 through the air assist pipe 26. At this time, the flow rate adjusting electromagnetic valve 25 constituting one specific example of the “adjusting means” in the present invention is controlled by the ECU 30 constituting one specific example of the “first control means” and the “second control means” in the present invention. The flow rate of the auxiliary compressed air sprayed (that is, supplied) to the exhaust turbine 11 is adjusted. For example, when the flow regulating electromagnetic valve 25 is in a closed state, auxiliary compressed air is not sprayed onto the exhaust turbine 11. On the other hand, when the flow rate adjusting electromagnetic valve 25 is in an open state, auxiliary compressed air having a flow rate according to the degree of opening of the flow rate adjusting electromagnetic valve 25 (that is, the opening area) is sprayed onto the exhaust turbine 11. . The adjustment operation of the flow rate of the auxiliary compressed air sprayed from the pressure accumulation tank 21 to the exhaust turbine 11 will be described in detail later (see FIG. 2).

  As a result, unburned components in the exhaust gas are combusted to raise the exhaust gas temperature and increase the flow rate of the exhaust gas. As a result, the rotational speed of the turbine can be increased. In particular, even when the amount of exhaust gas emission is small, such as in the low-speed rotation range of the engine in the early stage of acceleration of the vehicle, the rotational speed of the exhaust turbine 11 can be suitably increased, and as a result, so-called turbo lag is improved. can do.

(2) Operation Principle Next, with reference to FIG. 2, the operation principle of the supercharging system for an internal combustion engine according to the present embodiment (specifically, the auxiliary compressed air sprayed from the accumulator tank 21 to the exhaust turbine 11). The principle of the flow rate adjustment operation will be described. FIG. 2 shows the flow of the operation of the supercharging system for an internal combustion engine according to the present embodiment (specifically, the operation of adjusting the flow rate of the auxiliary compressed air sprayed from the pressure accumulation tank 21 to the exhaust turbine 11). It is a flowchart shown notionally.

  As shown in FIG. 2, it is determined whether or not the vehicle has started acceleration (step S101). For example, when the engine 1 is in a full load state by depressing the accelerator pedal from a state where the engine 1 is in a low-load steady operation of 2/5 load or less at an arbitrary low rotational speed between 1000 and 1500 rpm, It may be determined that the vehicle has started to accelerate. Alternatively, it may be determined whether the vehicle has started acceleration by directly detecting the longitudinal acceleration with a sensor or the like.

  As a result of the determination in step S101, the vehicle has not started acceleration (specifically, for example, the vehicle is stopped, the vehicle is traveling at a substantially constant speed, or the vehicle is decelerating). If it is determined (step S101: No), the operation of determining whether or not the vehicle has started acceleration is continued.

  On the other hand, as a result of the determination in step S101, if it is determined that the vehicle has started acceleration (step S101: Yes), first, the flow rate adjusting electromagnetic valve 25 is set to a fully open state under the control of the ECU 30. (Step S102). That is, under the control of the ECU 30, the opening area of the flow rate adjusting electromagnetic valve 25 is set so that the opening area of the flow rate adjusting electromagnetic valve 25 is the same or substantially the same as the pipe area of the air assist pipe 26. In other words, the opening area of the flow rate adjusting solenoid valve 25 is set so that the opening area of the flow rate adjusting solenoid valve 25 is maximized under the control of the ECU 30 at the initial stage when the vehicle starts to accelerate (that is, the initial stage of acceleration). Is done. For this reason, the auxiliary compressed air accumulated in the pressure accumulating tank 21 is sprayed onto the exhaust turbine 11 while maintaining the maximum flow rate.

  Thereafter, it is determined whether or not the rotational speed of the exhaust turbine 11 is 0.7 times or 0.9 times or more than the first target rotational speed (step S103). In other words, it is determined whether the rotational speed of the turbine has increased to some extent and the initial acceleration of the vehicle has ended.

  The first target rotational speed is, for example, the engine full load state when the engine 1 is depressed at a low speed between 1000 rpm and 1500 rpm and the steady operation state with a low load of 2/5 or less. Is the steady rotational speed (that is, steady turbo rotational speed) of the exhaust turbine 11 when the auxiliary compressed air is not sprayed onto the exhaust turbine 11 in the acceleration operation.

  In the present embodiment, whether or not the initial acceleration of the vehicle has ended is determined depending on whether the rotational speed of the exhaust turbine 11 is 0.7 times or 0.9 times or more than the first target rotational speed. is doing. However, it is configured to determine whether or not the initial acceleration of the vehicle has ended, depending on whether the rotational speed of the exhaust turbine 11 is N (where 0 <N <1) times or more the first target rotational speed. May be. This constant “N” is preferably defined for each vehicle according to the characteristics of the vehicle, the characteristics of the engine 1, the characteristics of the supercharging system for the internal combustion engine, the acceleration characteristics of the vehicle, and the like. Alternatively, an optimum value may be calculated each time under the control of the ECU 30 according to the characteristics of the vehicle, the characteristics of the engine 1, the characteristics of the internal combustion engine supercharging system, the acceleration characteristics of the vehicle, and the like.

  As a result of the determination in step S103, the rotational speed of the exhaust turbine 11 is not 0.7 times or 0.9 times the first target rotational speed (that is, the rotational speed of the exhaust turbine 11 is 0 of the first target rotational speed). .. or less than 0.9 times) (step S103: No), the process returns to step S102, and the exhaust gas turbine 11 is again set while the flow rate adjusting electromagnetic valve 25 is set to the fully open state. Is determined to be 0.7 times or 0.9 times or more than the first target speed.

  On the other hand, as a result of the determination in step S103, if it is determined that the rotational speed of the exhaust turbine 11 is 0.7 times or 0.9 times or more than the first target rotational speed (step S103: Yes), then, Thus, it is determined whether or not the rotational speed of the exhaust turbine 11 is equal to or higher than the second target rotational speed (step S104).

  The second target rotational speed is a range of mathematical values between the first target rotational speed and 0.7 times or 0.9 times the first target rotational speed (that is, the rotational speed used in the determination in step S103). It is specified by a function (for example, N-order function monomial or polynomial) obtained by connecting with a curve specified using a method, a statistical method, a theoretical method, or the like. And the 2nd target number of rotations specified by a target function increases gradually with progress of time. More specifically, the target function has a value equal to or lower than the first target rotational speed and 0.7 times or 0.9 times the first target rotational speed, and the first target rotational speed after a predetermined time has elapsed. A function that converges to a number (more preferably, converges smoothly). For example, the target function is a function whose initial value is 0.7 times or 0.9 times the first target rotational speed and whose final value is the first target rotational speed. For this reason, the second target rotational speed gradually approaches the first target rotational speed as time elapses, with 0.7 to 0.9 times the first target rotational speed as an initial value.

  As a result of the determination in step S104, when it is determined that the rotational speed of the exhaust turbine 11 is not equal to or higher than the second target rotational speed (step S104: No), the flow rate adjusting electromagnetic valve 25 is fully closed under the control of the ECU 30. The state is set (step S105). That is, auxiliary compressed air is no longer sprayed onto the exhaust turbine 11, and as a result, the rotational speed of the exhaust turbine 11 decreases.

  On the other hand, as a result of the determination in step S104, when it is determined that the rotation speed of the exhaust turbine 11 is not equal to or higher than the second target rotation speed (step S104: No), the flow rate adjusting electromagnetic valve 25 is controlled under the control of the ECU 30. The fully closed state is set (step S105). That is, auxiliary compressed air is sprayed onto the exhaust turbine 11 and, as a result, the rotational speed of the exhaust turbine 11 increases.

  Thereafter, according to the second target rotational speed indicated by the target function, the above process is continued until at least the rotational speed of the exhaust turbine 11 reaches the first target rotational speed (step S107). In other words, the rotational speed of the exhaust turbine 11 gradually increases in the same manner as the second target rotational speed specified by the target function (that is, the rotational speed of the exhaust turbine 11 becomes equal to the second target rotational speed). The flow rate of the auxiliary compressed air is adjusted (in other words, the open / close state of the flow rate adjusting electromagnetic valve 25 is controlled). In other words, while monitoring the actual rotational speed of the exhaust turbine 11, feedback control is performed so that the rotational speed follows the second target rotational speed, and the flow rate of the auxiliary compressed air is adjusted.

  Here, the actual rotational speed of the exhaust turbine 11 will be described with reference to FIG. FIG. 3 is a graph conceptually showing a time change of the rotational speed of the exhaust turbine 11 by the internal combustion engine supercharging system according to the present embodiment.

  As shown in FIG. 3, in the initial stage of acceleration, which is immediately after the vehicle starts acceleration, the flow rate of the auxiliary compressed air sprayed to the exhaust turbine 11 is maximized by setting the flow rate adjusting electromagnetic valve 25 to the fully open state. Therefore, the rotation speed of the exhaust turbine 11 increases rapidly.

  After the rotational speed of the exhaust turbine 11 exceeds 0.7 times or 0.9 times the first target rotational speed (that is, late acceleration), the second target rotational speed indicated by the thick dotted line in FIG. , The target function) as a target rotational speed, the rotational speed of the exhaust turbine 11 increases.

  In the graph of FIG. 3, an increase mode of the exhaust turbine 11 is described in consideration of a realistic response of feedback control. In other words, in the above-described embodiment, the flow rate of the auxiliary compressed air is adjusted depending on whether the rotational speed of the exhaust turbine 11 is equal to or higher than the second target rotational speed. 3 is described so as to increase or decrease (in other words, to vibrate) around the second target rotation speed. However, if the responsiveness of the feedback control is improved, the aspect is the same or substantially the same as the aspect of increasing the second target rotational speed (that is, the rotational speed of the exhaust turbine 11 increases or decreases around the second target rotational speed). The rotational speed of the exhaust turbine 11 can be increased.

  As described above, according to the internal combustion engine charging system according to this embodiment, first, the state in which the flow rate of the auxiliary compressed air immediately after the acceleration of the vehicle is started (that is, at the initial stage of acceleration) is the maximum flow rate. Since it can be maintained, the turbo lag immediately after the acceleration of the vehicle is started can be improved.

  Thereafter, after the rotational speed of the exhaust turbine 11 exceeds 0.7 times or 0.9 times the first target rotational speed (that is, in the later stage of acceleration), the rotational speed of the exhaust turbine 11 becomes the second target rotational speed. The flow rate of the auxiliary compressed air is adjusted so as to follow. For this reason, there is little or no fear that the rotational speed of the exhaust turbine 11 will increase excessively. In particular, the second target rotational speed increases so as to gradually approach the first target rotational speed with the passage of time, with 0.7 to 0.9 times the first target rotational speed being an initial value. The rotational speed of the exhaust turbine 11 can be increased smoothly. That is, it is possible to suitably increase the rotational speed of the exhaust turbine 11 while preferably preventing the disadvantage that the rotational speed of the exhaust turbine 11 overshoots.

  Furthermore, since the flow rate of the auxiliary compressed air is appropriately reduced according to the rotational speed of the exhaust turbine 11 (in other words, the flow rate adjusting electromagnetic valve 25 is set to a fully closed state), the accumulator tank 21 is in the middle of acceleration. The possibility of using up the auxiliary compressed air accumulated in the air can be suitably prevented. That is, the auxiliary compressed air accumulated in the pressure accumulating tank 21 can be used efficiently and effectively.

  Thus, according to this embodiment, the rotational speed of the exhaust turbine 11 can be increased smoothly or stably, and the rotational speed of the exhaust turbine 11 can be stabilized. That is, the stability of the supercharging system for the internal combustion engine can be improved.

  In the above-described embodiment, the flow rate adjusting electromagnetic valve 25 has been described as a specific example of the “adjusting means”. However, it is not always necessary to be a solenoid valve, and the flow rate of the auxiliary compressed air can be adjusted. If it is, it can be used instead of the flow rate adjusting electromagnetic valve 25. Furthermore, if it is a structure which can adjust the flow volume of the auxiliary compressed air which flows through air assist piping even if it is not a valve, it can be used instead of the flow volume adjustment electromagnetic valve 25. FIG.

  Furthermore, in the above-described embodiment, the flow rate of the auxiliary compressed air is adjusted according to the rotational speed of the exhaust turbine 11 (in other words, the open / close state of the flow rate adjusting electromagnetic valve 25 is controlled). However, instead of the rotational speed of the exhaust turbine 11, the flow rate of the auxiliary compressed air may be adjusted according to the intake pressure (or the supercharging pressure or the rotational speed of the compressor 12). In this case, the intake pressure (or the supercharging pressure or the rotational speed of the compressor 12) is determined in accordance with the rotational speed of the exhaust turbine 11, so that the flow rate of the auxiliary compressed air is the same as in the above-described embodiment. Can be adjusted. Specifically, in the initial stage of acceleration, until the intake pressure (or supercharging pressure or the rotation speed of the compressor 12) becomes 0.7 times or 0.9 times (or N times) the first target value. The flow rate of the auxiliary compressed air may be maximized. In the later stage of acceleration, the intake pressure (or supercharging pressure or the rotational speed of the compressor 12) is varied between the first target value and 0.7 to 0.9 times the first target value. The flow rate of the auxiliary compressed air is adjusted so that the second target value specified by the target function, which is a function obtained by connecting with a curve specified using a method, a statistical method, or a theoretical method, is used. May be.

  Further, in the above-described embodiment, the flow rate of the auxiliary compressed air is increased by setting the flow rate adjusting electromagnetic valve 25 to the fully open state, and the flow rate of the auxiliary compressed air is set by setting the flow rate adjusting electromagnetic valve 25 to the fully closed state. Is decreasing. However, by appropriately setting the opening area of the flow rate adjusting electromagnetic valve 25 (that is, depending on the degree of opening of the flow rate adjusting electromagnetic valve 25), the auxiliary compressed air is set so that the flow rate of the auxiliary compressed air becomes an arbitrary flow rate. The flow rate may be increased or decreased.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. The feeding system is also included in the technical scope of the present invention.

It is a block diagram which shows notionally the basic composition of the embodiment concerning the supercharging system for internal-combustion engines concerning this embodiment. It is a flowchart which shows notionally the flow of operation | movement of the internal combustion engine supercharging system which concerns on this embodiment (specifically, adjustment operation | movement of the flow volume of the auxiliary | assistant compressed air sprayed from a pressure accumulation tank to a turbine). It is a graph which shows notionally the time change of the rotation speed of the turbine by the supercharging system for internal combustion engines concerning this embodiment, and the flow volume of auxiliary compressed air.

Explanation of symbols

1 Engine 3 Exhaust Manifold 4 Intake Manifold 11 Turbine 12 Compressor 13 Rotary Shaft 14 Air Cleaner 15 Intercooler 21 Accumulation Tank 22 Check Valve 23 Auxiliary Compressed Air Piping 24 Auxiliary Compressed Air Supply Device 25 Flow Control Solenoid Valve 26 Air Assist Piping 30 ECU

Claims (4)

A supercharger comprising an exhaust turbine;
An accumulator tank for supplying auxiliary air to the exhaust turbine;
Adjusting means for adjusting the flow rate of the auxiliary air supplied from the pressure accumulation tank to the exhaust turbine;
The adjusting means is arranged so that the flow rate of the auxiliary air becomes a maximum flow rate until the rotational speed of the exhaust turbine reaches an initial target rotational speed that is N times the first target rotational speed (where 0 <N <1). First control means for controlling;
After the rotational speed of the exhaust turbine exceeds the first target rotational speed, the rotational speed of the exhaust turbine has a value equal to or lower than the first target rotational speed and equal to or higher than the initial target rotational speed and for a predetermined time. And a second control means for controlling the adjusting means so as to follow a second target rotational speed indicated by a target function that converges to the first target rotational speed after elapse of Supercharging system.   2. The supercharging system for an internal combustion engine according to claim 1, wherein the initial target rotational speed is 0.7 times or 0.9 times the first target rotational speed.   The supercharging system for an internal combustion engine according to claim 1 or 2, wherein the first target rotational speed is a steady rotational speed of the exhaust turbine when the auxiliary air is not supplied.   The second control means relatively increases the flow rate of the auxiliary air when the rotational speed of the exhaust turbine becomes equal to or lower than the second target rotational speed, and the rotational speed of the exhaust turbine is set to the second target rotational speed. 4. The internal combustion engine engine according to claim 1, wherein when the engine speed exceeds a rotational speed, the adjustment unit is controlled so as to relatively reduce the flow rate of the auxiliary air. 5. Supply system.

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