JPH10157613A - Abnormality detecting device for brake negative pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly and reliably detect abnormality of a brake negative pressure sensor regardless of running environment. SOLUTION: A fuel injection valve 11 is arranged at the peripheral part of the inner wall of a cylinder head 4 in the vicinity of first and second intake valves 6a and 6b of an engine 1, and fuel from the fuel injection valve 11 is injected directly in a cylinder 1a. An electronic control unit(ECU) 30 performs control of closing of a throttle valve 23 based on the output value (a pressure in a brake booster) of a pressure sensor 63 to ensure introduction of a negative pressure to a brake booster 71 for braking a vehicle. During detection abnormality of the pressure sensor 63, the ECU 30 decides that abnormality occurs to a pressure sensor 63 when the output value of the pressure sensor 63 attains a value outside a given range determined based on the output value of an intake pressure sensor 61 arranged at a surge tank 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting an abnormality of a brake negative pressure sensor, and more particularly to a brake booster for assisting a driver's braking operation based on a negative pressure. The present invention relates to an abnormality detection device for a brake negative pressure sensor for detecting internal pressure.

[0002]

2. Description of the Related Art Conventionally, as a technique relating to a pressure sensor for detecting a fluid pressure, for example, Japanese Utility Model Application Laid-Open No. 5-8167.
No. 6 is known. In this technique, the pressure of the fluid is read by a semiconductor pressure sensor,
The pressure value is compared with a predetermined value.
Then, when the read pressure value becomes equal to or more than a predetermined value, it is determined that an abnormality has occurred in the pressure sensor.

Incidentally, it is conceivable to apply this technique to detecting an abnormality of a brake negative pressure sensor for detecting the internal pressure of a brake booster. Here, the brake negative pressure sensor is provided in a brake booster. The brake booster is connected to an intake pipe of an engine mounted on the vehicle, and assists a driver's brake operation based on a negative pressure introduced into the brake booster.

[0004]

However, when the technique disclosed in the above-mentioned conventional publication is applied to the brake negative pressure sensor, the following problems may occur. That is, the environment in which the vehicle travels is wide, and therefore, the internal pressure of the brake booster also fluctuates greatly depending on weather conditions and height differences. Therefore, the range of values that the internal pressure of the brake booster can take is also large.
On the other hand, in the above-described related art, the determination value (predetermined value) for determining an abnormality is a predetermined fixed value. Therefore, the determination value must be a value that the brake negative pressure sensor cannot practically take in consideration of all conditions and the like.

[0005] Under such circumstances, even if an abnormality occurs due to the so-called out-of-range of the output value (pressure value) of the sensor, depending on the driving conditions, the output value may be out of the above-mentioned judgment value. Time may be required. Further, depending on the case, there is a possibility that a case where an abnormality cannot be detected may occur.

On the other hand, if the judgment value is set (the judgment margin is set small) in order to accelerate the abnormality detection, the possibility of erroneous detection may increase.
The present invention has been made in view of the above circumstances,
The purpose is to detect an abnormality of the sensor in the brake negative pressure sensor for detecting the internal pressure of the brake booster for securing the braking force of the vehicle based on the negative pressure, regardless of the traveling environment, Another object of the present invention is to provide an abnormality detection device for a brake negative pressure sensor capable of reliably detecting the abnormality.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, based on a negative pressure which is connected to an intake pipe of an engine mounted on a vehicle and introduced into the inside thereof. A device provided in a brake booster for assisting a driver's brake operation, for detecting an abnormality of a brake negative pressure sensor for detecting an internal pressure of the brake booster, wherein a pressure in an intake pipe of the engine is provided. The output of the brake negative pressure sensor is set to a value outside a predetermined range determined based on the detection result of the intake pressure detecting means. The gist of the invention is to provide an abnormality determining means for determining that an abnormality has occurred in the sensor.

(Operation) According to the first aspect of the present invention, the brake booster connected to the intake pipe of the engine assists the driver's braking operation based on the negative pressure introduced therein.

In the present invention, when an abnormality occurs in the brake negative pressure sensor, the abnormality can be detected as follows. That is, first, the pressure in the intake pipe of the engine is detected by the intake pressure detecting means. And
When the output value of the brake negative pressure sensor becomes a value outside a predetermined range determined based on the detection result of the intake pressure detecting means, the abnormality determining means determines that an abnormality has occurred in the brake negative pressure sensor. It is determined.

Therefore, even if a difference occurs in the internal pressure of the brake booster due to the running environment of the vehicle, the detection result of the intake pressure detecting means also differs according to the running environment. Therefore, the determination level according to the traveling environment is appropriately formed.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an apparatus for detecting an abnormality of a brake negative pressure sensor according to the present invention. However, the brake negative pressure sensor according to the present embodiment is embodied in a case where the brake negative pressure sensor is mounted on an engine capable of performing “stratified combustion”. Therefore, first, as a premise, a technique of “stratified combustion” will be briefly described.

Conventionally, in a generally used engine, fuel from a fuel injection valve is injected into an intake port, and a homogeneous mixture of fuel and air is supplied to a combustion chamber in advance. In such an engine, an intake passage is opened and closed by a throttle valve linked to an accelerator operation, and by this opening and closing, the amount of intake air supplied to a combustion chamber of the engine (consequently, a gas mixture in which fuel and air are homogeneously mixed). ) Is adjusted, thereby controlling the engine output.

However, in the technique based on the so-called homogeneous combustion described above, a large intake negative pressure is generated with the throttle operation of the throttle valve, so that the pumping loss increases and the efficiency decreases. On the other hand, by reducing the throttle of the throttle valve and supplying fuel directly to the combustion chamber, a combustible mixture is present near the ignition plug, and the air-fuel ratio of the portion is increased,
There is known a so-called "stratified combustion" technique for improving ignitability. In this technology, when the engine is under a low load, the injected fuel is unevenly supplied around the spark plug, and the throttle valve is opened almost fully to perform stratified combustion. As a result, the pumping loss is reduced, and the fuel efficiency is improved.

(First Embodiment) FIG. 1 shows a first embodiment.
FIG. 2 is a schematic configuration diagram illustrating an abnormality detection device of a brake negative pressure sensor in a stratified combustion engine mounted on a vehicle in the embodiment. The engine 1 has, for example, four cylinders 1
The combustion chamber structure of each of the cylinders 1a is shown in FIG. As shown in these drawings, the engine 1 includes a piston in a cylinder block 2, and the piston reciprocates in the cylinder block 2. A cylinder head 4 is provided above the cylinder block 2, and a combustion chamber 5 is formed between the piston and the cylinder head 4. Further, in the present embodiment, four valves are arranged for each cylinder 1a.
a represents a first intake valve, 6b represents a second intake valve, 7a represents a first intake port, 7b represents a second intake port, 8 represents a pair of exhaust valves, and 9 represents a pair of exhaust ports.

As shown in FIG. 2, the first intake port 7a
Is composed of a helical intake port, and the second intake port 7
b consists of a straight port extending almost straight.
In addition, an ignition plug 10 is disposed at the center of the inner wall surface of the cylinder head 4. This spark plug 10 includes:
The igniter 12 via a distributor (not shown)
Is applied. And
The ignition timing of the ignition plug 10 is determined by the igniter 1
2 is determined by the output timing of the high voltage. Further, a fuel injection valve 11 is disposed around the inner wall surface of the cylinder head 4 near the first intake valve 6a and the second intake valve 6b. That is, in the present embodiment, the fuel from the fuel injection valve 11 is directly injected into the cylinder 1a, so that not only homogeneous combustion but also so-called stratified combustion is performed. I have.

As shown in FIG. 1, a first intake port 7a and a second intake port 7b of each cylinder 1a are connected via a first intake path 15a and a second intake path 15b formed in each intake manifold 15, respectively. Connected to the surge tank 16. A swirl control valve 17 is arranged in each second intake passage 15b. These swirl control valves 17 are connected to, for example, a step motor 19 via a common shaft 18. The step motor 19 is controlled based on an output signal from an electronic control unit (hereinafter simply referred to as “ECU”) 30 described later. Instead of the step motor 19, a motor controlled according to the negative pressure of the intake ports 7a and 7b of the engine 1 may be used.

The surge tank 16 includes an intake duct 20
Is connected to the air cleaner 21 through the intake duct 20.
Inside, a throttle valve 23 which is opened and closed by a step motor 22 is provided. That is, the throttle valve 23 of the present embodiment is of a so-called electronic control type.
The throttle valve 23 is controlled to open and close by being driven based on the output signal from the controller. By opening and closing the throttle valve 23, the amount of intake air introduced into the combustion chamber 5 through the intake duct 20 is adjusted, and the negative pressure generated in the intake duct 20 is reduced. It is being adjusted. In the present embodiment, an intake pipe is constituted by the intake duct 20, the surge tank 16, the first intake path 15a, the second intake path 15b, and the like.

In the vicinity of the throttle valve 23, a throttle sensor 25 for detecting its opening (throttle opening TA) is provided. An exhaust manifold 14 is connected to the exhaust port 9 of each cylinder.
The exhaust gas after combustion is discharged to an exhaust pipe (not shown) through the exhaust manifold 14.

Further, in the present embodiment, a known exhaust gas recirculation (EGR) mechanism 51 is provided. This E
The GR mechanism 51 includes an EGR passage 52 as an exhaust gas recirculation passage, and an EGR valve 53 provided in the middle of the EGR passage 52. The EGR passage 52 is provided so as to communicate between the intake duct 20 downstream of the throttle valve 23 and the exhaust duct. Also, the EGR valve 53
Has a built-in valve seat, valve body, and step motor (all not shown). The opening degree of the EGR valve 53 fluctuates when the stepping motor intermittently displaces the valve body with respect to the valve seat. When the EGR valve 53 is opened, a part of the exhaust gas discharged to the exhaust duct flows to the EGR passage 52. The exhaust gas flows to the intake duct 20 via the EGR valve 53. That is,
Part of the exhaust gas is recirculated into the intake air-fuel mixture by the EGR mechanism 51. At this time, the recirculation amount of the exhaust gas is adjusted by adjusting the opening degree of the EGR valve 53.

Further, as shown in FIG. 1, in the present embodiment, a brake booster 71 is provided as a device for assisting a driver to perform a brake operation. The brake booster 71 amplifies the depressing force of the brake pedal 81 via the output rod 82, converts the amplified depressing force into hydraulic pressure in a master cylinder (not shown), and applies a brake actuator (see FIG. (Not shown) is driven. More specifically, the brake booster 71 includes a constant pressure chamber 73 and a variable pressure chamber 74 partitioned by a diaphragm 72. Diaphragm 72
Are airtightly fixed to the output rod 82. Constant pressure chamber 73
Is connected to the intake duct 20 downstream of the throttle valve 23 via a connection pipe 75, and is configured to introduce a negative pressure generated in the duct 20. The connection pipe 75 is provided with a check valve 76 that opens only when the pressure in the intake duct 20 is lower than the pressure in the constant-pressure chamber 73. Further, the brake booster 71
Is provided with a pressure sensor 63 as a brake negative pressure sensor for detecting a brake booster internal pressure PBK (absolute pressure in the present embodiment) on the constant pressure chamber 73 side.

On the other hand, when the brake pedal 81 is not depressed on the side of the variable pressure chamber 74, the negative pressure generated in the intake duct 20 is similar to that of the constant pressure chamber 73 through a communication path (not shown) with the constant pressure chamber 73. Pressure has been introduced. Then, when the brake pedal 81 is depressed, the communication path is shut off, and according to the amount of depression of the brake pedal,
Atmosphere is introduced from the air introduction port 77. Then, the brake booster 71 controls the pressure in the transformation chamber 74 formed according to the amount of depression of the brake pedal,
The difference between the pressure in the constant pressure chamber 73 and the pressure in the constant pressure chamber 73 assists the driver in braking.

The above-described ECU 30 is formed of a digital computer, and is connected to a RAM (random access memory) 3 via a bidirectional bus 31.
2, a ROM (Read Only Memory) 33, a CPU (Central Processing Unit) 34 composed of a microprocessor, an input port 35 and an output port 36. In the present embodiment, the ECU 30 constitutes abnormality determination means.

The accelerator pedal 24 is connected to an accelerator sensor 26A for generating an output voltage proportional to the amount of depression of the accelerator pedal 24, and the accelerator sensor 26A detects the accelerator opening ACCP.
The output voltage of the accelerator sensor 26A is
7 to the input port 35. Similarly, the accelerator pedal 24 has a fully-closed switch 2 for detecting that the depression amount of the accelerator pedal 24 is “0”.
6B are provided. That is, the fully closed switch 2
6B generates a signal of “1” as the fully closed signal XIDL when the depression amount of the accelerator pedal 24 is “0”, and generates a signal of “0” otherwise. The output voltage of the fully closed switch 26B is also input to the input port 35.

The top dead center sensor 27 generates an output pulse when the first cylinder 1a reaches the intake top dead center, for example.
This output pulse is input to the input port 35. The crank angle sensor 28 has a crankshaft of 30 ° CA, for example.
An output pulse is generated each time the motor rotates, and the output pulse is input to the input port. In the CPU 34, the top dead center sensor 2
7 and the output pulse of the crank angle sensor 28, the engine speed NE is calculated (read).

Further, the rotation angle of the shaft 18 is detected by a swirl control valve sensor 29,
Thereby, the opening of the swirl control valve 17 is measured. The output of the swirl control valve sensor 29 is supplied to an input port 35 via an A / D converter 37.
Is input to

At the same time, the throttle sensor 25 detects the throttle opening TA. The output of the throttle sensor 25 is input to an input port 35 via an A / D converter 37.

In addition, in the present embodiment, an intake pressure sensor 61 is provided as intake pressure detecting means for detecting the pressure (intake pressure PM) in the surge tank 16. further,
In the present embodiment, a water temperature sensor 62 that detects the temperature of the cooling water of the engine 1 (cooling water temperature THW) is provided. In addition, a vehicle speed sensor 64 for detecting a vehicle speed (vehicle speed) SPD is also provided. The outputs of these sensors 61, 62, 64 are also input to the input port 35 via the A / D converter 37. The output of the pressure sensor 63 is also input to the input port 35 via the A / D converter 37.

In the present embodiment, the throttle sensor 25, the accelerator sensor 26A, the fully closed switch 26
B, top dead center sensor 27, crank angle sensor 28, swirl control valve sensor 29, intake pressure sensor 61,
The operating state of the engine 1 is detected by a water temperature sensor 62, a pressure sensor 63, a vehicle speed sensor 64, and the like.

On the other hand, the output port 36 is connected to each fuel injection valve 11 and each step motor 1 via a corresponding drive circuit 38.
9, 22, the igniter 12 and the EGR valve 53 (step motor). Then, the ECU 30 according to a control program stored in the ROM 33 based on signals from the sensors 25 to 29, 61 to 64, etc.
The fuel injection valve 11, the step motors 19 and 22, the igniter 12 (spark plug 10), the EGR valve 53 and the like are suitably controlled.

Next, a description will be given of the basic control contents according to the present embodiment in the engine 1 having the above configuration. That is, in the present embodiment, since stratified charge combustion can be performed, control is frequently performed such that the opening of the throttle valve 23 is almost fully opened. Therefore, if no control is performed, the negative pressure downstream of the throttle valve 23 tends to be insufficient. Therefore, in the present embodiment, control for introducing a negative pressure into the constant pressure chamber 73 of the brake booster 71 by controlling the throttle valve 23 (step motor 22) is basically performed.

In this control, when the ECU 30 determines that stratified charge combustion is being performed, the ECU 30 determines the basic throttle opening based on various detection signals (accelerator opening ACCP, engine speed NE, etc.) that are currently being read. TRTB
Is calculated. At the same time, it is determined whether or not a detection signal from the pressure sensor 63 [the pressure PBK in the brake booster (a pressure relative to the atmospheric pressure is also possible)] is larger than a predetermined threshold value. For example, when the brake booster internal pressure PBK is higher than a predetermined threshold value, it is determined that the negative pressure in the brake booster 71 is insufficient, and the throttle pressure separately calculated from the basic throttle opening TRTB is determined. The value obtained by subtracting the closing amount TRTCBK is set as the final target throttle opening TRT. As described above, the ECU 30 operates the throttle valve 23 based on the detection result from the pressure sensor 63 to secure the negative pressure required to operate the brake booster 71.
Execute the confinement control of.

Next, the processing for detecting an abnormality of the pressure sensor 63 according to the present invention will be described. That is, FIG. 3 is a flowchart showing an “abnormality determination routine” executed by the ECU 30 to detect an abnormality of the pressure sensor 63 in the present embodiment. This routine is started, for example, when the engine 1 is started. You.

When the processing shifts to this routine, the ECU
First, in step 101, it is determined whether or not a precondition for detecting an abnormality is satisfied. Here, the preconditions include the following.

(1) Current pressure PB in the brake booster
K is between the maximum intake pressure PMmax and the minimum intake pressure PMmin. Here, the maximum intake pressure PMmax is the intake pressure P read immediately after the engine 1 is started.
M means the maximum value until now, and the minimum intake pressure PMmin means the minimum value of the intake pressure PM read immediately after the start of the engine 1 up to the present.

This is because the brake booster internal pressure PBK is originally formed by the intake pressure PM. That is, the brake booster internal pressure PBK is determined by the maximum intake pressure PMmax and the minimum intake pressure Pmax.
If it is not between Mmin and Mmin, it is considered that there is no abnormality in the intake pressure sensor 61 or the like, and it is not in a state where the abnormality of the pressure sensor 63 is detected.

(2) A predetermined time (for example, “2 seconds”) has elapsed since the engine 1 was started. This is to prohibit abnormality detection in such a region immediately after the start of the engine 1 because the battery voltage drops and it is difficult to make a normal determination.

(3) The intake pressure sensor 61 is not abnormal. In the present embodiment, since the abnormality of the pressure sensor 63 is determined based on the detection result of the intake pressure sensor 61, if the intake pressure sensor 61 is abnormal, the abnormality of the pressure sensor 63 is detected. Because it is not in a state.

In addition, the following preconditions can be given. The following conditions are conditions under which the intake pressure PM (minimum intake pressure PMmin) in the surge tank 16 can be reduced, and the brake booster internal pressure PBK can be reduced (negative pressure is secured). That is,
By adopting these conditions, a negative pressure can be secured in the brake booster 71, and the accuracy of detecting an abnormality of the pressure sensor 63 can be increased.

(4-a) At the time of starting the engine 1,
The idling state and the state where the engine section NE is at or above a predetermined rotation speed (for example, “600 rpm”) have continued for a predetermined time (for example, “10 seconds”).

When such a condition is satisfied, the throttle valve 23 is relatively closed, and negative pressure tends to accumulate in the surge tank 16. For this reason, the surge tank 16
The intake pressure PM (minimum intake pressure PMmin) can be reduced, and the brake booster internal pressure PBK can be reduced (negative pressure can be secured).

(4-b) Fuel cut is not being performed. When such a condition is not satisfied, that is, when the fuel is being cut, the engine speed NE decreases, and the intake pressure PM increases. For this reason, from the viewpoint of lowering the brake booster internal pressure PBK (securing a negative pressure), a condition that fuel cut is not being performed is given.

(4-c) After the completion of warm-up of the engine 1 [after a predetermined time (for example, "120 seconds" have elapsed) since the start of the engine 1. When such a condition is not satisfied, that is, at the time of a cold start, the throttle valve is used. In this case, the intake pressure PM (minimum intake pressure PMmin) is unlikely to decrease, and from such a viewpoint, a condition that the engine 1 has been completely warmed up can be mentioned.

(4-d) The operating state (mode) is the homogeneous combustion mode (in the present embodiment, the combustion mode is switched between the homogeneous combustion mode and the stratified combustion mode depending on the operating state). That is,
In general, the stratified combustion mode is adopted for low and medium loads, and the homogeneous combustion mode is adopted for high loads. ).

When such a condition is not satisfied, that is, in the stratified charge combustion mode, the throttle valve 23 is almost opened, and the intake pressure PM (minimum intake pressure PMmin) does not easily decrease. Therefore, from such a viewpoint, the condition that the combustion mode is the homogeneous combustion mode can be given as a condition.

If it is determined in step 101 that the precondition for detecting the above-described abnormality has been satisfied, the process proceeds to step 104 described later. On the other hand, when it is determined that the precondition for detecting the abnormality is not satisfied, the process proceeds to step 102.
In step 102, it is determined whether or not the above prerequisites are not satisfied even after repeated running and stopping of the vehicle.
If the above prerequisites are not satisfied as a result of repeating running and stopping of the vehicle, the process proceeds to step 107 described later. On the other hand, if the above precondition is satisfied as a result of repeating the running and stopping of the vehicle, step 10 is executed.
Move to 3.

In step 103, it is determined whether or not the brake booster internal pressure PBK is fixed at a substantially constant value. Here, as a case where the brake booster internal pressure PBK is fixed to a substantially constant value,
Short circuit, disconnection, disconnection of piping, etc. are considered. Then, even when the brake booster internal pressure PBK is fixed to a substantially constant value, the process proceeds to step 107 described later. On the other hand, if the brake booster internal pressure PBK has not been fixed to a substantially constant value, the routine proceeds to step 104 in order to allow the pressure sensor 63 to detect abnormality. That is, when the determination in step 101 is affirmative, or when the determination in step 104 is negative, the process proceeds to step 104.

In step 104, it is determined whether or not the state in which the brake booster internal pressure PBK is higher than the maximum intake pressure PMmax has been established for a certain period of time. Here, as described above, since the pressure is formed by the brake booster internal pressure PBK, the brake booster internal pressure PBK is normally the maximum intake pressure PMm
ax should not be exceeded. Therefore, after the preconditions are satisfied, the brake booster internal pressure PBK becomes the maximum intake pressure PBK.
If the state larger than Mmax is established for a certain period of time or longer, it is determined that there is a high possibility that an abnormality has occurred in the pressure sensor 63. Therefore, when an affirmative determination is made in step 104, the process proceeds to step 107 described later. On the other hand, if the state in which the brake booster internal pressure PBK is higher than the maximum intake pressure PMmax has not been established for a certain period of time, the routine proceeds to the next step 105.

In step 105, it is determined whether or not the state in which the brake booster internal pressure PBK is smaller than the minimum intake pressure PMmin has been established for a certain period of time. Here, as described above, since the pressure is formed by the brake booster internal pressure PBK, the brake booster internal pressure PBK should not fall below the minimum intake pressure PMmin in a normal state. Therefore, after the preconditions are satisfied,
The brake booster internal pressure PBK is the minimum intake pressure PMmin
If a state smaller than
It is determined that there is a high possibility that an abnormality has occurred in the pressure sensor 63. Therefore, when an affirmative determination is made in step 105, the process proceeds to step 107 described later.
On the other hand, if the state in which the brake booster internal pressure PBK is smaller than the minimum intake pressure PMmin has not been established for a certain period of time, the process proceeds to the next step 106.

In step 106, it is determined whether or not the brake booster internal pressure PBK has been fixed to a substantially constant value. And the pressure PB in the brake booster
When K is fixed to a substantially constant value, it is determined that there is a high possibility that an abnormality has occurred in the pressure sensor 63 system due to a short circuit, disconnection, disconnection of a pipe, or the like. Therefore, in such a case, the process proceeds to step 107 described later. On the other hand, if the brake booster internal pressure PBK is not fixed to a substantially constant value, it is determined that no abnormality has occurred in the pressure sensor 63 at present, and the process returns to step 104. Then, the processing of steps 104 to 106 is repeatedly executed.

If an affirmative determination is made in steps 102 to 106, it is determined that there is a high possibility that an abnormality has occurred in the pressure sensor 63 system, and the routine proceeds to step 107. In step 107, EC
U30 executes a fail-safe process. The following (1) to (3) are examples of the fail-safe processing.

(1) Forcibly perform the operation in the homogeneous combustion mode (stoichiometric operation). (2) Regardless of the pressure PBK in the brake booster detected by the pressure sensor 63, the closing control of the throttle valve 23 is executed at predetermined time intervals to always maintain the negative pressure in the brake booster 71.

Further, in this case, the speed of the past negative pressure consumption is learned, and if the negative pressure consumption is fast, the interval for executing the closing control is shortened, or the closing control is performed. It is even more desirable to increase the time that is running. By such control, it is possible to prevent a difference in the manner of consuming the negative pressure depending on the number of times and the strength of depressing the brake pedal.

(3) When the brake pedal is depressed by the brake input signal, the closing control or the stoichiometric operation is always executed. Then, step 1 described above
In 07, after executing the fail-safe processing, the EC
U30 proceeds to step 108.

In step 108, even after executing the fail-safe process, it is still determined whether any of steps 102 to 106 has repeatedly been affirmatively determined. If any of Steps 102 to 106 is repeatedly affirmatively determined, the fail-safe processing is useless and the pressure sensor 6
It is determined that an abnormality has occurred in the three systems, and an abnormality is detected. Then, the subsequent processing ends once.

On the other hand, if the affirmative determination is no longer repeated in any of steps 102 to 106 due to the execution of the fail-safe processing, the process proceeds to step 110. Step 110
In, while canceling the fail-safe processing,
Thereafter, the processing is temporarily terminated. In this case, the process returns to step 101 again.

Next, the operation and effect of this embodiment will be described. (A) In the present embodiment, the brake booster internal pressure PB
When the state where K is larger than the maximum intake pressure PMmax is established for a certain period of time or when the brake booster internal pressure PBK
Is established for a certain period of time or longer, it is determined that there is a high possibility that an abnormality has occurred in the pressure sensor 63. In other words, when the output value of the pressure sensor 63 falls outside a predetermined range determined based on the output value of the intake pressure sensor 61, it is determined that the pressure sensor 63 has failed.

Therefore, even if a difference occurs in the internal pressure of the brake booster 71 due to the running environment of the vehicle such as a weather condition or a height difference, the output value of the intake pressure sensor 61 also differs according to the running environment. . Therefore, the determination level according to the traveling environment is appropriately formed.
As a result, the abnormality of the pressure sensor 63 can be promptly and reliably detected regardless of the traveling environment.

(B) In this embodiment, the abnormality of the pressure sensor 63 is detected based on the output value of the intake pressure sensor 61. Here, the intake pressure sensor 61 is not provided only for detecting an abnormality of the pressure sensor 63, but is basically for detecting an operating state of the engine 1 for separately calculating a fuel injection amount or the like. Is generally provided as one of the means. Therefore, it is not necessary to provide a special detecting means separately in order to detect an abnormality of the pressure sensor 63, and it is possible to suppress an increase in cost.

(Second Embodiment) Next, a second embodiment of the present invention will be described. However, since the configuration and the like of this embodiment are the same as those of the above-described first embodiment, the same members and the like are denoted by the same reference numerals and description thereof is omitted. And, below, the first
The following description focuses on differences from the first embodiment.

In this embodiment, in terms of detection conditions,
Steps 104 to 10 of the first embodiment
6 and different. That is, FIG. 4 shows that the ECU 3 detects an abnormality of the pressure sensor 63 in the present embodiment.
7 is a flowchart illustrating a part of an “abnormality determination routine” executed by the routine of FIG.

When the processing shifts to this routine, the ECU
First, in step 101, it is determined whether or not a precondition for detecting an abnormality is satisfied. If the precondition is satisfied, the process proceeds to step 201.

In step 201, the intake pressure PM detected by the intake pressure sensor 61 is changed to the minimum intake pressure PMmi.
It is determined whether or not the state in which the brake booster pressure PBK is smaller than the value obtained by subtracting the predetermined value b from the current intake pressure PM has been smaller than the value obtained by adding the predetermined value a to n for a certain period of time. . If an affirmative determination is made in step 201, it is determined that the detection value of the pressure sensor 63 is out of range on the lower side, and it is highly likely that an abnormality has occurred in the pressure sensor 63 system. The process proceeds to step 107 described in the first embodiment. And
In step 107, the ECU 30 executes the fail-safe process, and if the abnormality is still not resolved, performs the abnormality detection.

On the other hand, if a negative determination is made in step 201, the process proceeds to step 202. In step 202, the intake pressure PM detected by the intake pressure sensor 61 is smaller than a value obtained by adding a predetermined value a to the minimum intake pressure PMmin, and the brake booster internal pressure PB
It is determined whether or not the state in which K is larger than the current intake pressure PM plus the predetermined value c has continued for a certain period of time. If an affirmative determination is made in step 202, it is determined that the detection value of the pressure sensor 63 is out of the upper range, and it is highly likely that an abnormality has occurred in the pressure sensor 63 system. Similarly, the process proceeds to step 107. Then, in step 107, the ECU 30
If the fail-safe processing is executed and the abnormality is still not resolved, the abnormality is detected.

On the other hand, if a negative determination is also made in step 202, the process returns to step 201, and the processes in steps 201 and 202 are repeated. Next, the function and effect of the present embodiment will be described.

(C) In this embodiment, basically, the same operation and effect as described in the first embodiment can be obtained. In addition, in this embodiment, the abnormality is detected by comparing the brake booster internal pressure PBK with the current intake pressure PM. Therefore, the range of abnormality detection can be varied according to the intake pressure PM at that time, and furthermore, the running conditions at that time, and timely detection becomes possible. As a result, abnormality detection can be performed more severely, and thus erroneous detection can be more reliably prevented.

At the same time, the present intake pressure PM is compared with a value obtained by adding a predetermined value a to the minimum intake pressure PMmin. Therefore, it is possible to improve the accuracy of the determination when the abnormality is determined using the current intake pressure PM. As a result, abnormality detection can be performed more severely.

The embodiment is not limited to the above, but may be modified as follows. (1) In the above embodiment, as means for applying a negative pressure to the brake booster 71, an electronic control including the throttle valve 23 provided in the intake duct 20 and the step motor 22 for opening and closing the throttle valve 23 is used. Although it is constituted by a throttle mechanism, it may be constituted by an ISC mechanism comprising an idle speed control valve provided in a bypass intake passage that bypasses the throttle valve 23 and an actuator for opening and closing the valve.

Further, E provided with the EGR valve 53 and the like
It may be constituted by the GR mechanism 51. Further, a negative pressure generating mechanism (not shown) may be separately provided. In these cases, a mechanical throttle valve linked to an accelerator pedal 24 may be used instead of the so-called electronically controlled throttle valve 23.

Further, these may be appropriately combined. (2) In the above embodiment, the present invention is embodied in the in-cylinder injection type engine 1. However, other types of internal combustion engines that perform so-called stratified combustion or weakly stratified combustion may be used. For example, intake valves 6a, 6b of intake ports 7a, 7b
The type that sprays toward the back side of the umbrella part is also included. Although a fuel injection valve is provided on the intake valves 6a and 6b side, a type in which fuel is injected directly into the cylinder bore (combustion chamber 5) is also included. Alternatively, the present invention may be embodied in an internal combustion engine that does not perform stratified combustion.

(3) In the above-described embodiment, the helical intake port is provided so that a so-called swirl can be generated. However, the swirl need not always be generated. Therefore, for example, the swirl control valve 17, the step motor 19, and the like in the above embodiment can be omitted.

(4) In the above embodiment, the present invention is embodied in the case of the gasoline engine 1 as the internal combustion engine. However, the present invention can be embodied in the case of a diesel engine or the like.

(4) Further, in the above embodiment, the intake pressure sensor 61 is used as the intake pressure detecting means. However, as another method for detecting the pressure in the intake duct 20, the throttle opening or the intake air amount may be used. The engine speed NE may be detected, and the pressure in the intake duct 20 may be estimated based on the detected engine speed NE.

The technical ideas which are not described in the claims and can be grasped from the above embodiment will be described below. (A) The abnormality detecting device for a brake negative pressure sensor according to claim 1, further comprising control means for controlling introduction of a negative pressure to the brake booster based on an output value of the brake negative pressure sensor. And

(B) The abnormality detecting device for a brake negative pressure sensor according to claim 1 or (a), wherein the engine can perform stratified combustion. (C) In the abnormality detection device for a brake negative pressure sensor according to claim 1 or the above (a) or (b), an output value of the intake pressure sensor is separately used for control calculation of the engine. It is characterized by being.

[0075]

As described in detail above, according to the present invention,
In the abnormality detection device of the brake negative pressure sensor for detecting the internal pressure of the brake booster for securing the braking force of the vehicle based on the negative pressure, regardless of the traveling environment, the abnormality of the sensor is promptly and reliably detected. It has an excellent effect that it can be detected.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an abnormality detection device for a brake negative pressure sensor according to a first embodiment.

FIG. 2 is an enlarged sectional view showing a cylinder portion of the engine.

FIG. 3 is an “abnormality determination routine” executed by an ECU.
It is a flowchart which shows.

FIG. 4 is a flowchart illustrating a part of an “abnormality determination routine” according to the second embodiment;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 11 ... Fuel injection valve, 1
6 ... Surge tank, 23 ... Throttle valve, 25 ... Throttle sensor, 26A ... Accelerator sensor, 26B ... Fully closed switch, 27 ... Top dead center sensor, 28 ... Crank angle sensor, 29 ... Swirl control valve sensor, 30 ...
ECU constituting abnormality determination means, 61 ... intake pressure sensor,
62: water temperature sensor, 63: pressure sensor as a brake negative pressure sensor, 71: brake booster, 72: diaphragm, 73: constant pressure chamber, 74: variable pressure chamber, 75: connection pipe,
81 ... Brake pedal.

Claims (1)

[Claims] 1. A brake booster, which is connected to an intake pipe of an engine mounted on a vehicle and assists a driver with a brake operation based on a negative pressure introduced therein, is provided in a brake booster. An intake pressure detecting means for detecting a pressure in an intake pipe of the engine, wherein an output value of the brake negative pressure sensor is the intake pressure. An abnormality determining unit that determines that an abnormality has occurred in the brake negative pressure sensor when a value outside a predetermined range determined based on a detection result of the detecting unit is provided. Abnormality detection device for pressure sensor.