JP2007327445A - Control device of negative pressure generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a negative pressure generator capable of suitably securing controllability of feedback control on ISC control. <P>SOLUTION: This control device of the negative pressure generator comprises an ejector for generating negative pressure larger than negative pressure tried to be taken out of an intake passage of an intake system of an internal combustion engine, and a state changing means for making the ejector function or stopping the function, and controls the negative pressure generator arranged in a passage independent of an idle flow rate adjusting means for adjusting an intake flow rate when idling the internal combustion engine, and has a controllability securing control means for controlling VSV 1 to stop the function of the ejector 30 when a feedback control quantity for controlling an electric throttle 13 by making a feedback process to restrain a variation in the intake flow rate, is a predetermined quantity α or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for a negative pressure generating device, and more particularly to a control device for a negative pressure generating device that controls a negative pressure generating device configured with an ejector.

  Conventionally, in a vehicle, a negative pressure larger than the negative pressure to be taken out from the intake passage of the intake system of the internal combustion engine communicating with each cylinder from the atmosphere (hereinafter also simply referred to as the intake system of the internal combustion engine) is supplied to the brake booster. An ejector is used to do this. The ejector is generally disposed in a bypass path that bypasses the throttle valve, and generates a larger negative pressure due to the venturi effect. Regarding this ejector, for example, Patent Document 1 proposes a negative pressure source device for a negative pressure booster using an ejector. In this negative pressure source device, a pressure sensor that detects that the negative pressure in the negative pressure chamber (hereinafter also simply referred to as a booster negative pressure) has become a predetermined value or less is used. By using such a pressure sensor, the ejector can be made to function so as to supply a larger negative pressure to the brake booster when the booster negative pressure decreases. Further, when the ejector is made to function, the intake air flows through the bypass passage, so that the intake air flow rate increases. On the other hand, Patent Document 2 proposes a vehicle control device that includes a correction unit that corrects an intake air amount sucked into an internal combustion engine based on an operating state of an ejector.

Sho 62-214245 JP 2005-69175 A

  Here, during idling, ISC control for controlling the idle speed is generally performed by controlling idle flow rate adjusting means such as an ISC (Idle Speed Control) valve and a throttle valve. The ISC control generally includes feedback control (hereinafter also simply referred to as F / B control) for controlling the idle flow rate adjusting means so as to suppress fluctuations in the idle rotation speed of the internal combustion engine, in other words, the intake flow rate. It is configured. In this F / B control, the difference between the target intake flow rate and the intake flow rate detected by an air flow meter or the like becomes a control amount (hereinafter also simply referred to as F / B control amount) for F / B control of the idle flow rate adjusting means. Reflected. Specifically, for example, when the detected intake air flow rate is increased from the target intake air flow rate as a result of the function of the ejector, the F / B control amount is an amount corresponding to the difference between the detected intake air flow rate and the target intake air flow rate. Only to decrease. Further, in this case, the idle flow rate adjusting means is F / B controlled so as to reduce the intake flow rate to the target intake flow rate in accordance with the magnitude of the F / B control amount, thereby suppressing fluctuations in the idle speed.

  However, when the magnitude of the F / B control amount reaches the lower limit, the F / B control amount does not become any smaller. Therefore, even if the intake flow rate fluctuates further, the idle rotation speed It becomes impossible to suppress the fluctuation. In particular, when the F / B control amount decreases as the intake flow rate increases when the ejector functions, the F / B control amount easily reaches the lower limit accordingly, so that the idling speed There is a possibility that the fluctuation of the above cannot be suppressed. In this respect, Patent Documents 1 and 2 do not particularly mention the controllability of the F / B control related to the ISC control. Therefore, when the ejector is functioned, there is a possibility that fluctuations in the idle rotation speed cannot be similarly suppressed. It is believed that there is. In addition, even when the F / B control amount reaches the upper limit, the F / B control amount does not increase any more. Therefore, even if the intake flow rate is further decreased, the idle rotation speed varies. Can no longer be suppressed. For example, if a deposit or the like is generated in a flow path that is opened and closed by the idle flow rate adjusting means, the intake air becomes difficult to circulate. Therefore, the F / B control amount constantly increases to compensate for the intake flow rate. In this case, since the F / B control amount easily reaches the upper limit, there is a possibility that fluctuations in the idling speed cannot be suppressed.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a control device for a negative pressure generator that can suitably ensure the controllability of feedback control related to ISC control.

  In order to solve the above-described problems, the present invention provides an ejector that generates a negative pressure larger than a negative pressure to be taken out from an intake passage of an intake system of an internal combustion engine, and a state changing unit that causes the ejector to function or stop functioning. And a negative pressure generator control device for controlling a negative pressure generator disposed in a path independent of the idle flow rate adjusting means for adjusting the intake flow rate during idling of the internal combustion engine. Control for controlling the state changing means to stop the function of the ejector when a feedback control amount for feedback control of the idle flow rate adjusting means is less than or equal to a predetermined amount so as to suppress fluctuations in the intake air flow rate. It is characterized by comprising a control means for ensuring reliability. Here, if the function of the ejector is stopped, the intake flow rate can be reduced. On the other hand, the intake flow rate is increased by F / B control in order to suppress fluctuations in the idle speed. That is, the F / B control amount can be increased at this time. As a result, even when the intake flow rate fluctuates further, fluctuations in the idle speed can be suppressed by the F / B control. Therefore, according to the present invention, the controllability of the F / B control according to the ISC control Can be secured.

  Further, the present invention includes an ejector that generates a negative pressure larger than the negative pressure to be taken out from the intake passage of the intake system of the internal combustion engine, and a state changing unit that functions or stops the function of the ejector. And a control device for a negative pressure generating device for controlling a negative pressure generating device disposed in a path independent of an idle flow rate adjusting means for adjusting an intake flow rate during idling of the internal combustion engine. Controllability ensuring control means for controlling the state changing means to cause the ejector to function when a feedback control amount for feedback control of the idle flow rate adjusting means to be suppressed is a predetermined amount or more. It is characterized by. Here, if the ejector is caused to function, the intake flow rate can be increased. On the other hand, the intake air flow rate is reduced by F / B control in order to suppress fluctuations in the idle speed. That is, the F / B control amount can be reduced at this time. As a result, even when the intake flow rate fluctuates so as to decrease, the fluctuation of the idling speed can be suppressed by the F / B control. According to the present invention, the controllability of the F / B control according to the ISC control Can be secured.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus of the negative pressure generator which can ensure suitably the controllability of the feedback control which concerns on ISC control can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram schematically showing a control device for a negative pressure generating device according to the present embodiment, which is realized by an ECU (Electronic Control Unit) 40A, together with the negative pressure generating device 100. The components shown in FIG. 1 including the internal combustion engine 50 are mounted on a vehicle (not shown). The intake system 10 of the internal combustion engine 50 includes an air cleaner 11, an air flow meter 12, an electric throttle 13, an intake manifold 14, an intake port (not shown) communicating with each cylinder (not shown) of the internal combustion engine 50, and the configuration thereof. For example, intake pipes 15a, 15b and the like are appropriately disposed between the two. The air cleaner 11 is configured to filter the intake air supplied to each cylinder of the internal combustion engine 50, and communicates with the atmosphere via an air duct (not shown). The air flow meter 12 is configured to measure the intake flow rate and outputs a signal corresponding to the intake flow rate.

  The electric throttle 13 includes a throttle valve 13a, a throttle body 13b, a valve shaft 13c, and an electric motor 13d. The throttle valve 13a is configured to adjust the total intake flow rate supplied to each cylinder of the internal combustion engine 50 by changing the opening. Further, the electric throttle 13 has a configuration for adjusting the intake flow rate in order to control the idle rotation speed. In this embodiment, the electric throttle 13 implements an idle flow rate adjusting means. The throttle body 13b is composed of a cylindrical member in which an intake passage is formed, and pivotally supports a valve shaft 13c of a throttle valve 13a disposed in the intake passage. The electric motor 13d is configured to change the opening degree of the throttle valve 13a under the control of the ECU 40A, and a step motor is adopted as the electric motor 13d. The electric motor 13d is fixed to the throttle body 13b, and its output shaft (not shown) is connected to the valve shaft 13c. The opening degree of the throttle valve 13 a is detected by the ECU 40 based on an output signal from an encoder (not shown) built in the electric throttle 13 (hereinafter simply referred to as an encoder).

  The throttle mechanism is preferably a throttle-by-wire system in which a throttle valve 13a such as an electric throttle 13 is driven by an actuator. However, the present invention is not limited to this. For example, a mechanical throttle mechanism in which the opening of the throttle valve 13a is changed in conjunction with an accelerator pedal (not shown) via a wire or the like instead of the electric throttle 13 may be applied. Good. In this case, for example, a bypass path is formed with respect to the throttle valve 13a, and the idling speed can be controlled by interposing a so-called ISC valve in the bypass path. Therefore, this ISC valve can be used as an idle flow rate adjusting means. The intake manifold 14 is configured to branch one intake passage on the upstream side corresponding to each cylinder of the internal combustion engine 50 on the downstream side, and distributes intake air to each cylinder of the internal combustion engine 50.

  The brake device 20 includes a brake pedal 21, a brake booster 22, a master cylinder 23, and a wheel cylinder (not shown). The brake pedal 21 operated by the driver to brake the rotation of the wheel is connected to an input rod (not shown) of the brake booster 22. The brake booster 22 is configured to generate an assist force with a predetermined boost ratio with respect to the pedal depression force, and a negative pressure chamber (not shown) internally partitioned on the master resin 23 side To the intake passage of the intake manifold 14. The output rod (not shown) of the brake booster 22 is further connected to the input shaft (not shown) of the master cylinder 23. The master cylinder 23 receives the assist force in addition to the pedal depression force. Hydraulic pressure is generated according to the applied force. The master cylinder 23 is connected to each wheel cylinder provided in a disc brake mechanism (not shown) of each wheel via a hydraulic circuit, and the wheel cylinder generates a braking force with the hydraulic pressure supplied from the master cylinder 23. . The brake booster 22 is not particularly limited as long as it is a pneumatic type, and may be a general one.

  The ejector 30 is configured to generate a negative pressure larger than the negative pressure to be taken out from the intake system 10, more specifically, the intake manifold 14, and supply it to the negative pressure chamber of the brake booster 22. The ejector 30 has an inflow port 31a, an outflow port 31b, and a negative pressure supply port 31c. Among these, the negative pressure supply port 31c is connected to the negative pressure chamber of the brake booster 22 by the air hose 5c. The inflow port 31a is connected to the intake passage of the intake pipe 15a by an air hose 5a, and the outflow port 31b is connected to the intake passage of the intake manifold 14 by an air hose 5b so as to sandwich the electric throttle 13, more specifically the throttle valve 13a. ing. Thus, a bypass path B that bypasses the electric throttle 13 is formed by the air hoses 5 a and 5 b including the ejector 30. When the ejector 30 is not functioning, the negative pressure chamber of the brake booster 22 is routed from the intake passage of the intake manifold 14 through the air hose 5b, the outlet port 31b of the ejector 30, the negative pressure supply port 31c, and the air hose 5c. Negative pressure is supplied.

  A VSV (vacuum switching valve) 1 is interposed in the air hose 5a. The VSV 1 is configured to communicate and block the bypass path B under the control of the ECU 40A. In the present embodiment, a 2-position 2-port normally closed solenoid valve is employed. However, the present invention is not limited to this, and the VSV 1 may be another appropriate electromagnetic valve or the like, and may be, for example, a flow rate adjustment valve that can control the degree of shielding of the flow path. The VSV 1 is configured to cause the ejector 30 to function or stop functioning by communicating and blocking the bypass path B. In the present embodiment, the state changing means is realized by VSV1.

  FIG. 2 is a diagram schematically showing the internal configuration of the ejector 30. The ejector 30 includes a diffuser 32 inside. The diffuser 32 includes a tapered taper portion 32a, a divergent taper portion 32b, and a negative pressure extraction portion 32c corresponding to a passage communicating these. The tapered taper portion 32a is opened so as to face the inflow port 31a, and the divergent taper portion 32b is opened so as to face the outflow port 31b. Moreover, the negative pressure extraction part 32c is connected to the negative pressure supply port 31c. The inflow port 31a is provided with a nozzle 33 for injecting the inflowing intake air toward the tapered portion 32a. The intake air injected from the nozzle 33 flows through the diffuser 32, and further from the outflow port 31b to the air hose 5b. To leak. At this time, a high-speed jet is generated in the diffuser 32 to generate a large negative pressure in the negative pressure extraction portion 32c due to the venturi effect, and this negative pressure is further reduced from the negative pressure supply port 31c through the air hose 5c to the negative pressure chamber. To be supplied. Due to the function of the ejector 30, the brake booster 22 can obtain a larger negative pressure than when the brake booster 22 is taken out from the intake manifold 14. The internal flow path between the negative pressure extraction part 32c and the negative pressure supply port 31c, the internal flow path between the outflow port 31b and the negative pressure supply port 31c, and the air hose 5c connection part of the brake booster 22 The provided reverse support valves 34 are for preventing backflow. Further, the ejector 30 is not limited to the one having the internal structure shown in FIG. 2, and an ejector having another different internal structure may be applied instead of the ejector 30.

  The ECU 40A includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output circuit, and the like (not shown). The ECU 40A mainly has a configuration for controlling the internal combustion engine 50. In this embodiment, the ECU 40A also controls the electric throttle 13 and the VSV1. In addition to the electric throttle 13 and VSV1, various control objects are connected to the ECU 40A via a drive circuit (not shown). The ECU 40A is connected to various sensors such as an encoder, an accelerator sensor (not shown) for detecting the state of the accelerator pedal, and a crank angle sensor (not shown) for detecting the rotational speed Ne of the internal combustion engine 50. .

  The ROM is configured to store a program in which various processes executed by the CPU are described. In the present embodiment, the function of the ejector 30 is set under various conditions in addition to the program for controlling the internal combustion engine 50, or A VSV1 control program for controlling the VSV1 so as to stop the function (hereinafter also simply referred to as turning on or off the VSV1), an ISC control program for performing ISC control of the electric throttle 13, and the like are stored. . However, these programs may be combined together. The ISC control program includes an ISC control request amount calculation program and an electric throttle control program for controlling the electric throttle 13 based on the calculated ISC control request amount. In addition to the F / B control amount, the ISC control request amount is a learning control amount for learning control of the electric throttle 13, and a correction for correcting and controlling the electric throttle 13 according to the operating state of the air conditioner and the electric load. It has a control amount and the like. The ISC control request amount calculation program is a program for calculating various control amounts constituting the ISC control request amount and calculating the sum of these as the ISC control request amount. Note that various control amounts constituting the ISC control request amount may have negative values.

  In this embodiment, the VSV1 control program is configured to have a first controllability ensuring program for turning off the VSV1 when the F / B control amount is equal to or less than the predetermined amount α. . In the present embodiment, various control means, detection means, determination means, and the like are realized by the CPU, ROM, RAM (hereinafter also referred to as CPU, etc.) and the above-described various programs. The control means for ensuring controllability is realized by the program for ensuring safety. In the present embodiment, the negative pressure generator 100 is realized by the VSV 1 and the ejector 30.

  Next, processing performed by the ECU 40A to control the VSV 1 will be described in detail with reference to the flowchart shown in FIG. The ECU 40A controls the negative pressure generating device 100 by repeatedly executing the processing shown in the flowchart in a very short time based on the above-described VSV1 control program and ISC control request amount calculation program stored in the ROM. To do. The CPU executes processing for determining whether (or whether) VSV1 is turned on (or step 11). Whether or not VSV1 is ON can be determined based on, for example, the output signal of a sensor such as a limit switch for detecting the operating state of VSV1, the state of internal processing performed by ECU 40A, or the like. it can. If the determination is affirmative, the CPU executes processing for determining whether or not the F / B control amount is equal to or less than a predetermined amount α (step 12). The predetermined amount α is, for example, a lower limit value of the F / B control amount, or an amount having a margin slightly higher than the lower limit value, so that the F / B control is performed without causing the ejector 30 to stop functioning more than necessary. It is preferable to ensure controllability.

  If an affirmative determination is made in step 12, the CPU executes a process for turning off VSV1 (step 13). At the same time, other controls that have turned on VSV1 are prohibited from controlling VSV1. Here, when the VSV 1 is turned off, the intake air flow is reduced because the intake air does not flow through the bypass passage B. On the other hand, the intake air flow rate is increased by F / B control so as to suppress fluctuations in the idling speed. That is, the F / B control amount can be increased at this time. As a result, even when the intake flow rate fluctuates so as to increase, the F / B control amount can be reduced, so that the controllability of the F / B control can be ensured. If a negative determination is made in step 11, the VSV 1 can be controlled under a predetermined condition (step 14). Also, if the determination at step 12 is negative, the processing shown at step 14 is similarly executed. In this case, other controls that have turned on VSV1 are still permitted to control VSV1. At the same time, if a negative determination is made in step 12, it is suppressed that the ejector 30 stops functioning more than necessary in securing the controllability of the F / B control, and the booster negative pressure is appropriately secured. As described above, the ECU 40A that can suitably ensure the controllability of the F / B control related to the ISC control can be realized.

  The ECU 40B according to the present embodiment is configured to have a second controllability ensuring program for turning on VSV1 when the VSV1 control program further has an F / B control amount equal to or larger than a predetermined amount β. The ECU 40A according to the first embodiment is the same as that of the first embodiment. However, the present invention is not limited to this, and the ECU 40B may be any ECU that stores at least the second controllability ensuring program in the ROM. Each configuration of the vehicle to which the ECU 40B is applied is the same as each configuration of the vehicle shown in FIG. 1 except for the ECU 40A. In this embodiment, the CPU or the like and the second controllability securing program realize the controllability securing control means, and the ECU 40B realizes the control device for the negative pressure generating device. Next, the process performed by the ECU 40B to control the VSV 1 will be described in detail with reference to the flowchart shown in FIG.

The CPU executes a process of determining whether (or whether) VSV1 is turned off (step 21). If the determination is affirmative, the CPU executes a process of determining whether or not the F / B control amount is larger than a predetermined amount β (step 22). The predetermined amount β is, for example, an upper limit value of the F / B control amount, or an amount having a margin slightly lower than the upper limit value so that the ejector 30 functions from the viewpoint of ensuring controllability of the F / B control. This is preferable. If an affirmative determination is made in step 22, the CPU executes a process for turning on VSV1 (step 23). Here, when the VSV 1 is turned on, the intake air flows through the bypass passage B, so that the intake air flow rate increases. On the other hand, the intake air flow rate is reduced by F / B control in order to suppress fluctuations in the idle speed. That is, the F / B control amount can be reduced at this time. As a result, even when the intake flow rate fluctuates so as to decrease, the F / B control amount can be increased, so that the controllability of the F / B control can be ensured.

  If the determination in step 21 is negative, other controls that turn on VSV1 are allowed to continue to control VSV1 (step 24). Also, if the determination at step 22 is negative, the processing shown at step 14 is executed in the same manner. In this case, the VSV 1 can be controlled under a predetermined condition. As described above, the ECU 40B that can suitably ensure the controllability of the F / B control related to the ISC control can be realized.

  The embodiment described above is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

2 is a diagram schematically showing an ECU 40A together with a negative pressure generator 100. FIG. 3 is a diagram schematically showing an internal configuration of an ejector 30. FIG. It is a figure which shows the process performed by ECU40A with a flowchart. It is a figure which shows the process performed by ECU40B with a flowchart.

Explanation of symbols

1 VSV
10 Intake System 13 Electric Throttle 20 Brake Device 22 Brake Booster 30 Ejector 40 ECU
50 Internal combustion engine 100 Negative pressure generator

Claims (2)

The internal combustion engine includes: an ejector that generates a negative pressure larger than the negative pressure to be taken out from an intake passage of an intake system of the internal combustion engine; and a state changing unit that causes the ejector to function or stop functioning. A control device for a negative pressure generating device for controlling a negative pressure generating device disposed in a path independent of an idle flow rate adjusting means for adjusting an intake flow rate at the time of idling,
Ensuring controllability to control the state changing means to stop the function of the ejector when a feedback control amount for feedback control of the idle flow rate adjusting means is equal to or less than a predetermined amount so as to suppress fluctuations in the intake flow rate A control device for a negative pressure generating device, comprising: The internal combustion engine includes: an ejector that generates a negative pressure larger than the negative pressure to be taken out from an intake passage of an intake system of the internal combustion engine; and a state changing unit that causes the ejector to function or stop functioning. A control device for a negative pressure generating device for controlling a negative pressure generating device disposed in a path independent of an idle flow rate adjusting means for adjusting an intake flow rate at the time of idling,
For ensuring controllability that controls the state changing means so that the ejector functions when a feedback control amount for feedback control of the idle flow rate adjusting means is greater than or equal to a predetermined amount so as to suppress fluctuations in the intake flow rate. A control device for a negative pressure generator, comprising a control means.

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