JP5318143B2 - Brake device for vehicle - Google Patents

Description

  The present invention relates to a vehicle brake device, and more particularly, to a vehicle brake device capable of determining an abnormality of a negative pressure detecting means connected to a negative pressure chamber of a negative pressure booster.

  In a vehicular brake device including a brake operation member such as a brake pedal, a hydraulic system and a negative pressure system are widely used to assist the operation of the brake operation member. The hydraulic system assists the operation of the brake pedal by adjusting the hydraulic pressure (brake hydraulic pressure) in the pipe connecting the master cylinder and the wheel cylinder with a plurality of valves. Moreover, a negative pressure system assists operation of a brake operation member by generating a negative pressure with a vacuum pump etc. according to operation of a brake operation member (patent document 1).

  In Patent Document 1, the output value of the pressure sensor (63) provided in the brake booster (71) connected to the intake pipe of the engine is based on the output value of the intake pressure sensor (61) that detects the pressure in the intake pipe. When the value is outside the predetermined range, it is determined that an abnormality has occurred in the pressure sensor (63) (summary, claim 1).

Japanese Patent Laid-Open No. 10-157613

  As described above, in Patent Document 1, abnormality of the pressure sensor is determined by comparing the output values of the pressure sensor (negative pressure sensor, negative pressure detecting means) and the intake pressure sensor. However, the configuration using the negative pressure in the intake pipe as the negative pressure in the brake booster (negative pressure booster) is mainly used in a vehicle equipped with a gasoline engine, but among diesel engines does not have a throttle valve. The intake pressure sensor cannot be used in a vehicle equipped with a vehicle or an electric vehicle without an engine. Further, in the configuration of Patent Document 1, it may be determined that an abnormality has occurred in the pressure sensor even when an abnormality has occurred in the intake pressure sensor.

  The present invention has been made in consideration of such problems, and it is possible to determine abnormality of the negative pressure detection means with a simple configuration without using the output of the intake pressure sensor (intake pressure detection means). An object of the present invention is to provide a vehicular brake device.

  The vehicle brake device according to the present invention is driven by a negative pressure detecting means connected to a negative pressure chamber of a negative pressure type booster, and driven by the negative pressure type booster in response to an operation input to the brake operation member. A master cylinder that pressurizes the wheel cylinder with the hydraulic pressure generated by the master cylinder to brake the wheel, and detects the master cylinder pressure or the wheel cylinder pressure, and the liquid A negative pressure estimating means for calculating a negative pressure estimated value in the negative pressure booster based on the master cylinder pressure or the wheel cylinder pressure detected by a pressure detecting means; a negative pressure estimated value estimated by the negative pressure estimating means; It further comprises an abnormality detection means for detecting an abnormality of the negative pressure detection means by comparing with a negative pressure detection value detected by the negative pressure detection means.

  According to this invention, the negative pressure estimated value based on the master cylinder pressure or the wheel cylinder pressure detected by the hydraulic pressure detecting means and the negative pressure detected value detected by the negative pressure detecting means are compared to determine whether the negative pressure detecting means is abnormal. Is detected. For this reason, it is possible to determine the abnormality of the negative pressure detecting means with a simple configuration without using the output of the intake pressure sensor. Therefore, the abnormality of the negative pressure detecting means can be determined with a simple configuration without depending on the type of vehicle {gasoline engine vehicle, diesel engine vehicle, electric vehicle (including hybrid vehicle and fuel cell vehicle)}. . Further, in order to estimate the negative pressure in the negative pressure type booster from the master cylinder pressure or the wheel cylinder pressure, if combined with other sensors (for example, another negative pressure detecting means, intake pressure sensor), from the viewpoint of fail-safe An excellent configuration can be realized.

The negative pressure estimator includes an operation input increase determination unit that determines an increase in operation input of the brake operation member, an operation input decrease determination unit that determines a decrease in operation input of the brake operation member, and an increase in the operation input And a negative pressure consumption calculation means for calculating an estimated value of the negative pressure consumption accompanying the decrease as an indication of the negative pressure estimated value. Thereby, both increase and decrease of the operation input of the brake operation member are used for calculation of the negative pressure estimated value. For this reason, it becomes possible to improve estimation precision rather than using one of the increase or decrease of the operation input of a brake operation member.
The abnormality detection means includes an estimated value of the negative pressure consumption calculated by the negative pressure consumption calculation means, and an actual measurement value of the negative pressure consumption based on the negative pressure detection value detected by the negative pressure detection means. May be detected to detect abnormality of the negative pressure detecting means.

  The abnormality detection unit may not perform abnormality detection of the negative pressure detection unit based on the estimated negative pressure value when the amount of time change of the negative pressure detection value is less than a predetermined value. For example, when the amount of change in the negative pressure detection value with time is small (that is, the fluctuation of the negative pressure is slight), erroneous determination may occur even if the negative pressure detection value is used. In such a case, it is possible to maintain high accuracy of abnormality detection by not performing abnormality detection of the negative pressure detecting means.

  The abnormality detection means performs the abnormality determination of the negative pressure detection means only when at least one of the negative pressure detection value, the negative pressure estimation value, the master cylinder pressure, and the wheel cylinder pressure satisfies a predetermined reference value. It may be configured to do. Thereby, it is possible to maintain high accuracy of abnormality detection by executing abnormality detection of the negative pressure detection means only when it is suitable.

  According to this invention, the negative pressure estimated value based on the master cylinder pressure or the wheel cylinder pressure detected by the hydraulic pressure detecting means and the negative pressure detected value detected by the negative pressure detecting means are compared to determine whether the negative pressure detecting means is abnormal. Is detected. For this reason, it is possible to determine the abnormality of the negative pressure detecting means without using the output of the intake pressure sensor. Therefore, the abnormality of the negative pressure detecting means can be determined without depending on the type of vehicle {gasoline engine vehicle, diesel engine vehicle, electric vehicle (including hybrid vehicle and fuel cell vehicle)}. Further, in order to estimate the negative pressure in the negative pressure type booster from the master cylinder pressure or the wheel cylinder pressure, if combined with other sensors (for example, another negative pressure detecting means, intake pressure sensor), from the viewpoint of fail-safe An excellent configuration can be realized.

1 is a schematic configuration diagram of a vehicle equipped with a vehicle brake device according to an embodiment of the present invention. It is a figure which shows the hardware structure of the electronic control apparatus contained in the said vehicle, and the function with which the said hardware structure is provided. It is a flowchart of the abnormality determination process which determines abnormality of a negative pressure sensor in the embodiment. It is a flowchart of abnormality determination in the embodiment. It is explanatory drawing regarding the process (calculation content) at the time of abnormality determination in the said electronic control apparatus. It is a figure which shows an example of the relationship between the brake fluid pressure at the time of brake pedal operation, and master power pressure variation | change_quantity. It is a flowchart which calculates M / P pressure estimation consumption in the said embodiment.

A. Embodiment 1 FIG. Configuration (1) Overall Configuration of Vehicle 10 FIG. 1 is a schematic configuration diagram of a vehicle 10 equipped with a brake device 11 according to this embodiment. The vehicle 10 of this embodiment is a diesel engine vehicle. The vehicle 10 may be a gasoline engine vehicle or an electric vehicle (including a hybrid vehicle and a fuel cell vehicle).

  The vehicle 10 includes an engine 12, an EGR bypass passage 14, a turbocharger 16, a brake pedal 18, a brake booster 20 (negative pressure booster), a hydraulic system 22, a negative pressure system 24, and electronic control. A device 26 (hereinafter referred to as “ECU 26”) and a warning lamp 28 are included. Among these, the brake pedal 11, the brake booster 20, the hydraulic system 22, the negative pressure system 24, the ECU 26, and the warning lamp 28 are included in the brake device 11. Further, the vehicle 10 includes an engine speed sensor 30, a water temperature sensor 32, an atmospheric pressure sensor 34, an outside air temperature sensor 36, a hydraulic pressure sensor 38, a negative pressure sensor 40, and a brake switch 42.

(2) Brake booster 20
The brake booster 20 is connected to the negative pressure pump 60 and boosts (increases) the operation input to the brake pedal 18. The brake booster 20 has a negative pressure chamber 200 and a variable pressure chamber 202 arranged with a diaphragm 204 interposed therebetween.

(3) Hydraulic system 22
The hydraulic system 22 is connected to the master cylinder 50 via a master cylinder 50 connected to the brake booster 20, a valve mechanism 52 provided with a plurality of electromagnetic valves (not shown), a valve mechanism 52 and a pipe 56, and a wheel 58. And a wheel cylinder 54 for imparting a braking force.

(4) Negative pressure system 24
The negative pressure system 24 includes a negative pressure pump 60 connected to the negative pressure chamber 200 of the brake booster 20 via a pipe 62, and a check valve 64 provided on the pipe 62. The EGR bypass passage 14 is connected to the pipe 62 via a vacuum switching valve 66 (hereinafter referred to as “VSV 66”), and via an electric vacuum regulating valve 68 (hereinafter referred to as “EVRV 68”). The turbocharger 16 is connected.

  The negative pressure pump 60 of the present embodiment is a method (direct acting type) driven by the rotational driving force of the engine 12. Instead, a method that does not depend on the rotational driving force of the engine 12 (for example, an electric type) may be used. The EGR bypass flow path 14 constitutes a part of an exhaust gas recirculation device (EGR).

(5) Various sensors The engine speed sensor 30 detects the speed of the engine 12 (hereinafter referred to as “engine speed NE”). The water temperature sensor 32 detects the coolant water temperature Tw of the engine 12. The atmospheric pressure sensor 34 detects the atmospheric pressure Pa. The outside air temperature sensor 36 detects the outside air temperature Ta. The hydraulic pressure sensor 38 detects the brake hydraulic pressure Pmc in the master cylinder 50. The negative pressure sensor 40 is connected to the negative pressure chamber 200 of the brake booster 20 and detects the pressure in the negative pressure chamber 200 (hereinafter referred to as “master power pressure PmpS” or “M / P pressure PmpS”).

(6) ECU26
The ECU 26 controls the engine 12, the turbocharger 16, the hydraulic system 22, the negative pressure system 24, and the warning lamp 28 via the communication line 98 and the like based on outputs (detected values) of various sensors.

  FIG. 2 shows a hardware configuration of the ECU 26 and functions provided in the hardware configuration. As shown in FIG. 2, the ECU 26 includes an input / output unit 70, a calculation unit 72, and a storage unit 74 as hardware.

  The calculation unit 72 executes a program stored in the storage unit 74 to thereby execute an engine control function 80, an antilock brake system control function 82 (hereinafter referred to as “ABS control function 82”), and a vehicle behavior stabilization system control. A function 84 (hereinafter referred to as “VSA control function 84”), a hill hold control function 86, a turbocharger control function 88 (hereinafter referred to as “T / C control function 88”), and a negative pressure system control function 90 are realized.

  The engine control function 80 is a function for controlling the engine 12 in accordance with an operation amount of an accelerator pedal (not shown). The ABS control function 82 is a function for preventing the wheel 58 from being locked when a braking force is applied from the hydraulic system 22 to the wheel 58 (during brake operation). The VSA control function 84 is a function that stabilizes the behavior of the vehicle 10. More specifically, the VSA control function 84 includes, for example, a traction control function that prevents idling of the wheel 58 during non-brake operation (acceleration, etc.), and a side slip that prevents a side slip when the vehicle 10 turns a curve or the like. A prevention function and an avoidance operation support function that assists the operation when the driver operates a steering handle (not shown) to avoid the vehicle 10 (vehicle) from an obstacle.

  The hill hold control function 86 is used when a predetermined condition (for example, a predetermined time has not elapsed since the release of the brake pedal 18) is satisfied even when the brake pedal 18 is not operated on a road inclined forward and backward, This is a function of regulating the movement of the vehicle 10 by operating an electric parking brake (not shown) or the wheel cylinder 54. The T / C control function 88 is a function for controlling the turbocharger 16 and includes a turbocharger failure detection function 92 (hereinafter referred to as “T / C failure detection function 92”).

  The negative pressure system control function 90 is a function for controlling the negative pressure system 24 (for example, the negative pressure pump 60), and includes a negative pressure sensor abnormality determination function 94. In the present embodiment, the calculation unit 72 can determine the abnormality of the negative pressure sensor 40 by executing the negative pressure sensor abnormality determination function 94.

2. Overview of Abnormality Determination Processing of Negative Pressure Sensor 40 in the Present Embodiment FIG. 3 is a flowchart of abnormality determination processing for determining abnormality of the negative pressure sensor 40. In step S1, the ECU 26 determines an abnormality determination condition. As an abnormality determination condition in the present embodiment, for example, at least one of being in an idle stop state and executing the hill hold control function 86 can be used.

  In step S2, the ECU 26 determines whether or not the abnormality determination condition is satisfied based on the determination result in step S1. If the abnormality determination condition is not satisfied (S2: NO), the current process is terminated. When the abnormality determination condition is satisfied (S2: YES), the process proceeds to step S3.

  In step S <b> 3, the ECU 26 determines abnormality of the negative pressure sensor 40. Details of the abnormality determination will be described later with reference to FIG. If the negative pressure sensor 40 is not abnormal as a result of step S3 (S4: NO), the ECU 26 ends the current process. If there is an abnormality in the negative pressure sensor 40 (S4: YES), in step S5, the ECU 26 issues a warning to the driver. Specifically, the ECU 26 turns on the warning lamp 28 and notifies the driver of the occurrence of an abnormality. Instead of this, or in addition to this, the ECU 26 may notify the driver of the occurrence of an abnormality by other methods such as issuing a warning sound using a speaker (not shown).

3. Abnormality determination (S3 in FIG. 3)
(1) Overview of Abnormality Determination FIG. 4 is a flowchart of abnormality determination (details of S3 in FIG. 3). Further details of the processing in FIG. 4 will be described later with reference to FIGS.

  In step S <b> 11, the ECU 26 acquires the master power pressure PmpS (detected value) from the negative pressure sensor 40.

  In step S12, the ECU 26 processes the M / P pressure PmpS for comparison with an estimated value to be described later, and measures the master power pressure actual consumption ΔPmpS (hereinafter referred to as “M / P pressure actual consumption ΔPmpS” or “actual consumption”). A quantity ΔPmpS ”). The actually measured M / P pressure consumption amount ΔPmpS indicates an actually measured value (cumulative value) of the M / P pressure PmpS consumed by operating the brake pedal 18, and is obtained based on the M / P pressure PmpS from the negative pressure sensor 40. .

  In step S13, the ECU 26 acquires the brake hydraulic pressure Pmc from the hydraulic pressure sensor 38. In step S14, the ECU 26 calculates a master power estimated consumption amount ΔPmpE (hereinafter referred to as “M / P pressure estimated consumption amount ΔPmpE” or “estimated consumption amount ΔPmpE”) based on the acquired brake fluid pressure Pmc. The estimated M / P pressure consumption ΔPmpE indicates an estimated value (cumulative value) of the M / P pressure PmpS consumed by the operation of the brake pedal 18 and is mainly obtained based on the brake fluid pressure Pmc.

  In step S15, the ECU 26 compares the measured consumption amount ΔPmpS calculated in step S12 with the estimated consumption amount ΔPmpE calculated in step S14 to determine the difference between the two. In subsequent step S16, the ECU 26 determines whether or not the difference between the actually measured consumption amount ΔPmpS and the estimated consumption amount ΔPmpE is large. If the difference between the two is not large (S16: NO), in step S17, the ECU 26 determines that the negative pressure sensor 40 is normal. When the difference between the two is large (S16: YES), in step S18, the ECU 26 determines that the negative pressure sensor 40 is abnormal.

(2) Details of Abnormality Determination FIG. 5 is an explanatory diagram regarding processing (calculation contents) at the time of abnormality determination. The process shown in FIG. 5 is performed by the calculation unit 72 of the ECU 26. The processing block 100 corresponds to the determination of the abnormality determination condition determined in step S1 of FIG. 3 and outputs an abnormality determination permission flag (calculation permission flag F1) to the processing block 106 when the abnormality determination condition (calculation permission condition) is satisfied. To do. The processing block 102 outputs the M / P pressure PmpS from the negative pressure sensor 40 to the processing blocks 106, 108 and 110. Here, the M / P pressure PmpS may be obtained by performing a predetermined filter process such as removal of a noise component. Further, the M / P pressure PmpS output from the processing block 102 to the processing block 110 may be only an initial value (hereinafter referred to as “initial value PmpS1”). The initial value PmpS1 is the M / P pressure PmpS immediately after the processing block 110 receives the calculation start flag F2 from the processing block 106. The processing block 104 outputs the brake hydraulic pressure Pmc from the hydraulic pressure sensor 38 to the processing blocks 106 and 110.

  The processing block 106 is based on the calculation permission flag F1 from the processing block 100, the M / P pressure PmpS (initial value PmpS1) from the processing block 102, and the brake fluid pressure Pmc from the processing block 104. The calculation start timing of the measured pressure consumption ΔPmpS and the estimated M / P pressure consumption ΔPmpE is determined. Specifically, when the M / P pressure PmpS and the brake fluid pressure Pmc at the time of receiving the calculation permission flag F1 are within the normal ranges, the calculation start flag F2 is output to the processing blocks 108 and 110.

  When receiving the calculation start flag F2 from the processing block 106, the processing block 108 calculates the M / P pressure actual consumption ΔPmpS based on the M / P pressure PmpS from the processing block 102. Specifically, the processing block 108 sets the M / P pressure PmpS at the time of receiving the calculation start flag F2 as the initial value PmpS1. Subsequently, when the ECU 26 subsequently receives new M / P pressure PmpS sequentially from the processing block 102, the ECU 26 calculates the difference between the received M / P pressure PmpS and the initial value PmpS1 as the actually measured consumption amount ΔPmpS {ΔPmpS = PmpS ( n) -PmpS1}. Then, the processing block 108 outputs the calculated actual consumption ΔPmpS to the determination block 114 and the processing block 120.

  When receiving the calculation start flag F2 from the processing block 106, the processing block 110 consumes the estimated M / P pressure based on the initial value PmpS1 of the M / P pressure PmpS from the processing block 102 and the brake pressure Pmc from the processing block 104. The quantity ΔPmpE is calculated. In calculating the estimated consumption amount ΔPmpE, as shown in FIG. 6, the M / P pressure PmpS is consumed regardless of whether the brake pedal 18 is depressed or returned {the M / P pressure PmpS The amount of change (hereinafter referred to as “M / P pressure change amount ΔPmp” or “change amount ΔPmp”) increases).

  That is, the combination of the change amount of the brake fluid pressure Pmc and the M / P pressure PmpS (M / P pressure change amount ΔPmp) at the time when the processing block 110 receives the calculation start flag F2 and starts the calculation is the point P1. In this case, when the brake pedal 18 is depressed, the brake fluid pressure Pmc increases, and the change amount ΔPmp (cumulative value) also increases accordingly. As a result, the point P2 is reached.

  Thereafter, when the brake pedal 18 is returned, the brake fluid pressure Pmc decreases and the change amount ΔPmp (cumulative value) increases. As a result, the point P3 is reached. When the brake pedal 18 is depressed again, the brake fluid pressure Pmc increases, and the change amount ΔPmp (cumulative value) also increases accordingly. Then, the combination of the brake fluid pressure Pmc and the M / P pressure change amount ΔPmp at the end of the calculation of the processing block 110 is a point P4. In this embodiment, the M / P pressure change amount ΔPmp while moving from the point P1 to the point P4 is used as the M / P pressure estimated consumption amount ΔPmpE.

  In the present embodiment, the estimated M / P pressure consumption amount ΔPmpE is proportional to the pressure in the negative pressure chamber 200 of the brake booster 20 (negative pressure chamber pressure Pp), and hence the estimated consumption amount from the negative pressure chamber pressure Pp. ΔPmpE can be obtained. In the present embodiment, when the brake pedal 18 is depressed, the negative pressure chamber pressure Pp is calculated from the pressure change of the negative pressure chamber 200 that changes by isothermal compression. Further, when the brake pedal 18 is returned, the negative pressure chamber pressure Pp is calculated from the balance of forces based on the brake booster 20. Furthermore, in the present embodiment, the pressure in the variable pressure chamber 202 of the brake booster 20 (the variable pressure chamber pressure Pr) can also be calculated. Specific calculation methods for the negative pressure chamber pressure Pp and the variable pressure chamber pressure Pr will be described later.

  The processing block 110 outputs the calculated M / P pressure estimated consumption amount ΔPmpE to the determination blocks 112 and 116 and the processing block 120.

  The determination block 112 determines whether or not the estimated consumption amount ΔPmpE from the processing block 110 exceeds a predetermined threshold value TH1 (100 hPa in the present embodiment), and sends an inclination calculation trigger Tr1 indicating the determination result to the processing block 120. Output. That is, the inclination calculation trigger Tr1 is output to the processing block 120 only when the estimated consumption amount ΔPmpE is larger than the threshold value TH1.

  The determination block 114 determines whether or not the actually measured consumption amount ΔPmpS from the processing block 108 exceeds a predetermined threshold value TH2 (100 hPa in the present embodiment), and outputs the determination result to the determination block 118. That is, the inclination calculation trigger Tr2 is output to the determination block 118 only when the actually measured consumption amount ΔPmpS is larger than the threshold value TH2.

  The determination block 116 determines whether or not the estimated consumption amount ΔPmpE from the processing block 110 exceeds a predetermined threshold value TH3 (10 hPa in this embodiment), and outputs the determination result to the determination block 118. That is, the inclination calculation trigger Tr3 is output to the determination block 118 only when the estimated consumption amount ΔPmpE is larger than the threshold value TH3. This makes it possible to prevent the denominator from becoming zero when calculating the slope Kpp (described later) in the processing block 120.

  The determination block 118 has the same function as a so-called AND-type logic circuit based on the determination results from the determination blocks 114 and 116. Specifically, the determination result from the determination block 114 is that the measured consumption amount ΔPmpS exceeds the threshold value TH2, and the determination result from the determination block 116 is that the estimated consumption amount ΔPmpE exceeds the threshold value TH3. Determine if there is. Then, the determination block 118 outputs an inclination calculation trigger Tr2 indicating the determination result to the processing block 120. That is, the inclination calculation trigger Tr2 is output to the processing block 120 only when the actually measured consumption amount ΔPmpS exceeds the threshold value TH2 and the estimated consumption amount ΔPmpE exceeds the threshold value TH3.

  The processing block 120 calculates a ratio (inclination Kpp) between the actually measured consumption amount ΔPmpS and the estimated consumption amount ΔPmpE from the processing block 108, and outputs it to the filter processing unit 122. When the inclination calculation trigger Tr1 is not input from the determination block 112, when the inclination calculation trigger Tr2 is not input from the determination block 118, or when the estimated consumption amount ΔPmpE is not input from the processing block 110, the processing block 120 Substitute 1 for each of ΔPmpS and estimated consumption ΔPmpE, and output the slope Kpp (= 1).

  The filter processing unit 122 performs a predetermined filter process on the slope Kpp from the processing block 120 as a slope Kppf after filtering. Specifically, a coefficient α that is larger than zero and smaller than 1 is set, the product of the coefficient α and the slope Kppf (n−1) after the previous filter, the difference between 1 and the coefficient α, and the current slope Kpp ( {Kppf (n) = α · Kppf (n-1) + (1-α) Kpp}, which is the sum of the product of n) and the slope Kppf (n) after the current filter. Thereby, it is possible to cancel a sudden change from the slope Kpp before correction and obtain a stable value. The filtered slope Kppf calculated by the filter processing unit 122 is stored in the storage unit 74 and also output to the decision blocks 126 and 128.

  The determination block 126 determines whether or not the filtered gradient Kppf is below a predetermined threshold value TH4 (0.50 in this embodiment), and outputs the result to the processing block 130. The determination block 128 determines whether or not the filtered gradient Kppf exceeds a predetermined threshold value TH5 (1.50 in this embodiment), and outputs the result to the processing block 130.

  The processing block 130 determines whether or not an abnormality has occurred in the negative pressure sensor 40 based on the outputs from the determination blocks 126 and 128. Specifically, when the output from the determination block 126 indicates that the slope Kppf is below the threshold value TH4, or the output from the determination block 128 indicates that the slope Kppf is above the threshold value TH5. If so, the processing block 130 determines that an abnormality has occurred in the negative pressure sensor 40. If an abnormality has occurred in the negative pressure sensor 40, the processing block 130 displays a warning on the warning lamp 28 and stores a failure code indicating that an abnormality has occurred in the negative pressure sensor 40 in the storage unit 74. To do.

(3) Detailed Flow of Calculation of M / P Pressure Estimated Consumption ΔPmpE FIG. 7 shows a flowchart for calculating M / P pressure estimated consumption ΔPmpE in processing block 110. In step S21, the processing block 110 acquires the initial value PmpS1 of the M / P pressure PmpS from the processing block 102. In step S <b> 22, the processing block 110 acquires the brake hydraulic pressure Pmc from the processing block 104.

  In step S23, the processing block 110 calculates a brake fluid pressure change amount ΔPmc which is a difference between the current value {Pmc (n)} of the brake fluid pressure Pmc and the previous value {Pmc (n−1)} {ΔPmc = Pmc (n) -Pmc (n-1)}.

  In step S24, the processing block 110 determines whether or not the brake pedal 18 is being depressed. Specifically, a threshold (depression determination threshold TH_ΔPmcH) for determining whether or not the brake pedal 18 is being depressed is set in advance, and the brake fluid pressure change amount ΔPmc calculated in step S23 is the threshold. It is determined whether or not TH_ΔPmcH is exceeded. When the brake pedal 18 is not depressed (S24: NO), the process proceeds to step S25.

  In step S25, the processing block 110 determines whether or not the brake pedal 18 is being returned. Specifically, a threshold value (return determination threshold value TH_ΔPmcL) for determining whether or not the brake pedal 18 is returning is set in advance, and the brake fluid pressure change amount ΔPmc calculated in step S23 is the threshold value. It is determined whether or not TH_ΔPmcL is below. If the brake pedal 18 is not being returned (S25: NO), the process proceeds to step S26.

  In step S <b> 26, the processing block 110 holds the previous value {Pp (n−1)} of the negative pressure chamber pressure Pp as it is as the current value {Pp (n)} of the negative pressure chamber pressure Pp and the variable pressure chamber pressure Pr. The previous value of {Pr (n-1)} is held as the current value {Pr (n)} of the variable pressure chamber pressure Pr. After step S26, the process proceeds to step S30.

  Returning to step S24, if the brake pedal 18 is being depressed (S24: YES), in step S27, the processing block 110 selects an arithmetic expression for the negative pressure chamber pressure Pp and the variable pressure chamber pressure Pr used at the time of depression, and the step Proceed to S29. In step S25, when the brake pedal 18 is being returned (S25: YES), in step S28, the processing block 110 selects arithmetic expressions for the negative pressure chamber pressure Pp and the variable pressure chamber pressure Pr used at the time of return, Proceed to step S29.

  In step S29, the processing block 110 calculates the current values of the negative pressure chamber pressure Pp and the variable pressure chamber pressure Pr using the calculation formula selected in step S27 or step S28 (specific calculation will be described later).

In step S <b> 30, the processing block 110 calculates the M / P pressure estimated consumption amount ΔPmpE and outputs it to the determination blocks 112 and 116 and the processing block 120. The estimated consumption amount ΔPmpE is calculated by the following equation (1).
ΔPmpE = PmpE−PmpS1 (1)

  In step S31, the processing block 110 determines whether or not the calculation started with the calculation start flag F2 from the processing block 106 is completed. If the calculation process has not ended (S31: NO), the process returns to step S22. When the calculation process is finished (S31: YES), the current process is finished.

(4) Specific Calculation Method (a) Definition Next, a specific calculation method for the negative pressure chamber pressure Pp and the variable pressure chamber pressure Pr will be described. First, various numerical values used for calculation are defined as follows.
(I) Variable Pp: negative pressure chamber pressure [Pa]
Pr: Transformer pressure [Pa]
x: Movement amount of the diaphragm 204 in the brake booster 20 [m]
(Ii) Constant A: Area of diaphragm 204 [m ² ]
a: Effective diameter [m ² ] of the master cylinder 50
Lp: Stroke amount of the negative pressure chamber 200 [m]
Lr: Stroke amount of the variable pressure chamber 202 [m]
S: constant of the brake booster 20 {magnification (servo ratio) -1} [no unit]
F _mc0 : Starting load of master cylinder 50 [N]
k _mc : Efficiency of master cylinder 50 [no unit]
(Iii) Sensor value Pmp: Master power pressure [Pa]
Pb: Intake pressure [Pa] in the pipe 62
Pmc: Brake fluid pressure [Pa]

(B) When the brake pedal 18 is depressed (i) Negative pressure chamber pressure Pp
When the gas in the closed space is compressed isothermally, the pressure P1 and the volume V1 before compression and the pressure P2 and the volume V2 after compression are expressed by the following equation (2-1) based on Boyle's law. be able to.
P1 · V1 = P2 · V2 (2-1)

By transforming equation (2-1), equation (2-2) can be derived.
P1 = (P2 · V2) / V1 (2-2)

  The above formula (2-2) can also be applied to the air in the negative pressure chamber 200 of the present embodiment.

Further, in the case of the air in the negative pressure chamber 200, the above equation (2-2) uses the stroke amount Lp of the negative pressure chamber 200 and the movement amount x of the diaphragm 204 in place of the volumes V1 and V2. (2-3).

  In Expression (2-3), “n−1” indicates a state before the brake pedal 18 is depressed, and “n” indicates a state after the brake pedal 18 is depressed.

Further, the moving amount x of the diaphragm 204 can be expressed by the following equation (2-4) as a function of the M / P pressure PmpS.
x = f (Pmc) (2-4)

ここで、負圧室圧力Ｐｐは、Ｍ／Ｐ圧ＰｍｐＳの推定値（推定Ｍ／Ｐ圧ＰｍｐＥ）とみなすことができる。 For this reason, the following formula (2-5) can be derived from the above formula (2-3) and formula (2-4).

Here, the negative pressure chamber pressure Pp can be regarded as an estimated value of the M / P pressure PmpS (estimated M / P pressure PmpE).

  Therefore, according to the above equation (2-5), the negative pressure chamber pressure Pp (= estimated M / P pressure PmpE) can be calculated from the brake fluid pressure Pmc before and after the brake pedal 18 is depressed.

(Ii) Transformer chamber pressure Pr
Since the force is balanced in the diaphragm 204 between the negative pressure chamber 200 and the variable pressure chamber 202, the following equation (3-1) can be derived.

When formula (3-1) is modified, formula (3-2) can be derived, and formula (3-3) can be derived from formula (3-2).

Here, the following expression (3-4) can be derived from the above expressions (2-5) and (3-3).

  Here, as described above, the movement amount x of the diaphragm 204 can be expressed as a function of the M / P pressure PmpS {see the above formula (2-4)}. Therefore, the variable pressure chamber pressure Pr can also be calculated from the brake fluid pressure Pmc before and after the brake pedal 18 is depressed.

(C) When the brake pedal 18 is returned A widely known gas equation of state is represented by the following equation (4-1).
PV = nRT (4-1)

  In the above formula (4-1), P is the pressure of the gas, V is the volume occupied by the gas, n is the amount of the gaseous substance (in moles), R is the gas constant, and T is the thermodynamic temperature of the gas.

Here, since the negative pressure chamber 200 is a closed space, the following equation (4-2) is derived from the gas state equation {equation (4-1)}.
nR (n) + nP (n) = nR (n-1) + nP (n-1) (4-2)

Furthermore, in the configuration of the present embodiment, using the negative pressure chamber pressure Pp, the variable pressure chamber pressure Pr, the stroke amount Lp of the negative pressure chamber 200, the stroke amount Lr of the variable pressure chamber 202, and the movement amount x of the diaphragm 204, the equation (4 -2) can be transformed into the equation (4-3).
Pr (n). {Lr + x (n)} + Pp (n). {Lp-x (n)} = Pr (n-1). {Lr + x (n-1)} + Pp (n-1). {Lp- x (n-1)} (4-3)

Here, the definition is as follows.
a = {Lr + x (n)}
β = {Lp−x (n)}
γ = Pr (n−1) · {Lr + x (n−1)}
d = Pp (n−1) · {Lp−x (n−1)}

ここで、上記式（３−２）及び式（４−４）より、負圧室圧力Ｐｐ及び変圧室圧力Ｐｒを解くと、次の式（４−５）及び式（４−６）を導くことができる。

Then, the following equation (4-4) can be derived from the equation (4-3) and the above definitions.

Here, when the negative pressure chamber pressure Pp and the variable pressure chamber pressure Pr are solved from the above equations (3-2) and (4-4), the following equations (4-5) and (4-6) are derived. be able to.

  Here, as described above, the movement amount x of the diaphragm 204 can be expressed as a function of the M / P pressure PmpS {see the above formula (2-4)}. Therefore, it can be calculated from the negative pressure chamber pressure Pp, the pressure change chamber pressure Pr, and the brake fluid pressure Pmc before and after the brake pedal 18 is depressed. The negative pressure chamber pressure Pp can be regarded as an estimated value of the M / P pressure PmpS (estimated M / P pressure PmpE).

4). As described above, according to the present embodiment, the M / P pressure estimated value PmpE (M / P pressure estimated consumption amount ΔPmpE) based on the brake fluid pressure Pmc detected by the fluid pressure sensor 38 is negative. The M / P pressure PmpS (M / P pressure actual consumption ΔPmpS) detected by the pressure sensor 40 is compared to detect an abnormality in the negative pressure sensor 40. For this reason, it is possible to determine the abnormality of the negative pressure sensor 40 with a simple configuration without using the output of the intake pressure sensor. Therefore, the abnormality of the negative pressure sensor 40 is determined without depending on the type of the vehicle 10 (or traveling drive source) {gasoline engine vehicle, diesel engine vehicle, electric vehicle (including hybrid vehicle and fuel cell vehicle)}. be able to. Moreover, since the negative pressure in the brake booster 20 is estimated by the brake fluid pressure Pmc, when combined with another sensor (for example, another negative pressure sensor or an intake pressure sensor), an excellent configuration can be realized from the viewpoint of fail-safety. It becomes.

  In the present embodiment, both increase and decrease of the operation input of the brake pedal 18 are used for calculating the M / P pressure estimated value PmpE (M / P pressure estimated consumption amount ΔPmpE). For this reason, it becomes possible to improve estimation accuracy rather than using one of the increase or decrease of the operation input of the brake pedal 18.

  In the present embodiment, the ECU 26 (negative pressure sensor abnormality determination function 94) detects abnormality of the negative pressure sensor 40 based on the estimated M / P pressure value PmpE when the measured M / P pressure consumption amount ΔPmpS is less than the threshold value TH2. Not performed (decision block 114 in FIG. 5). For example, when the actually measured consumption amount ΔPmpS is small (that is, the fluctuation of the negative pressure is slight), an erroneous determination may occur even when the M / P pressure PmpS is used. In such a case, it is possible to maintain high accuracy of abnormality detection by not detecting abnormality of the negative pressure sensor 40.

  The ECU 26 (negative pressure sensor abnormality determination function 94) is used only when the actually measured consumption ΔPmpS exceeds the threshold H2 (determination block 114) or when the estimated consumption ΔPmpE exceeds the thresholds TH1 and TH3 (determination blocks 112 and 116). An abnormality determination of the negative pressure sensor 40 is performed. Thereby, it is possible to maintain high accuracy of abnormality detection by executing abnormality detection of the negative pressure sensor 40 only when it is preferable.

B. Modifications It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the contents described in this specification. For example, the following configuration can be adopted.

1. Vehicle 10
In the above embodiment, the vehicle 10 is a diesel engine vehicle. However, the vehicle 10 is not limited thereto, and may be an electric vehicle (including a hybrid vehicle and a fuel cell vehicle) or a gasoline engine vehicle.

2. Negative pressure pump 60 (negative pressure generating means and method)
In the embodiment described above, the negative pressure pump 60 is a direct acting type driven by the engine 12, but is not limited thereto. For example, the negative pressure pump 60 may be electric.

  In the above embodiment, the negative pressure (M / P pressure PmpS) in the negative pressure system 24 can be generated by the negative pressure pump 60, the EGR bypass flow path 14, and the turbocharger 16, but means for generating negative pressure and The method is not limited to this. For example, it may be performed by any one or two of the negative pressure pump 60, the EGR bypass passage 14, and the turbocharger 16.

3. Abnormal determination of negative pressure sensor 40 In the above-described embodiment, the timing of performing the abnormal determination has been described as idling stop time and hill hold time, but is not limited to this, for example, when the vehicle 10 starts (return the brake pedal 18) Time) or running.

  In the embodiment described above, as the condition for determining the abnormality of the negative pressure sensor 40, the actually measured M / P pressure consumption ΔPmpS exceeds the threshold TH2 (determination block 114), and the estimated M / P pressure consumption ΔPmpE is set to the thresholds TH1 and TH3. Although exceeding (decision block 112,116) was mentioned, it is not restricted to this. For example, the abnormality determination of the negative pressure sensor 40 may be executed only when the brake fluid pressure Pmc satisfies a predetermined reference value.

4). Estimated M / P pressure PmpE and estimated M / P pressure consumption ΔPmpE
In the above-described embodiment, the estimated M / P pressure PmpE and the estimated M / P pressure consumption amount ΔPmpE are calculated based on the brake fluid pressure Pmc (master cylinder pressure) in the master cylinder 50. Brake fluid pressure (wheel cylinder pressure) in the cylinder 54 may be used.

5. Others In the above embodiment, the abnormality of the negative pressure sensor 40 is determined based on the detection value (brake hydraulic pressure Pmc) of the hydraulic pressure sensor 38. Conversely, the operation of the hydraulic pressure sensor 38 is determined from the detection value of the negative pressure sensor 40. Abnormality can also be determined. In other words, in addition to the hydraulic pressure sensor 38 and the negative pressure sensor 40, means for monitoring an abnormality of the hydraulic pressure sensor 38 or the negative pressure sensor 40 (for example, another negative pressure sensor or an intake pressure sensor as in Patent Document 1) is provided. If it does, it can be set as the structure excellent in the viewpoint of fail safe.

DESCRIPTION OF SYMBOLS 10 ... Vehicle 11 ... Brake device 18 for vehicles ... Brake pedal (brake operation member)
20 ... Brake booster (negative pressure booster)
26 ... ECU (negative pressure estimation means, abnormality detection means, operation input increase determination section, operation input decrease determination section, negative pressure consumption calculation means, estimated value calculation means)
38 ... Hydraulic pressure sensor (hydraulic pressure detecting means) 40 ... Negative pressure sensor (negative pressure detecting means)
50 ... Master cylinder 54 ... Wheel cylinder 58 ... Wheel 200 ... Negative pressure chamber Pmc ... Brake fluid pressure PmpS ... M / P pressure (negative pressure detection value)
PmpE: Estimated M / P pressure (negative pressure estimated value) ΔPmpE: M / P pressure estimated consumption ΔPmpS: M / P pressure measured consumption

Claims (3)

A negative pressure detecting means connected to the negative pressure chamber of the negative pressure booster; and a master cylinder driven by the negative pressure booster in response to an operation input to the brake operating member. A vehicular brake device that pressurizes a wheel cylinder with hydraulic pressure generated by the cylinder to brake the wheel,
Hydraulic pressure detecting means for detecting a master cylinder pressure or a wheel cylinder pressure;
Negative pressure estimating means for calculating a negative pressure estimated value in the negative pressure booster based on the master cylinder pressure or the wheel cylinder pressure detected by the hydraulic pressure detecting means;
An abnormality detecting means for detecting an abnormality of the negative pressure detecting means by comparing the negative pressure estimated value estimated by the negative pressure estimating means with the negative pressure detected value detected by the negative pressure detecting means ;
The negative pressure estimating means includes
An operation input increase determination unit for determining an increase in operation input of the brake operation member;
An operation input decrease determination unit that determines a decrease in operation input of the brake operation member;
Negative pressure consumption calculating means for calculating an estimated value of the negative pressure consumption accompanying the increase and decrease of the operation input as indicating the negative pressure estimated value;
With
The abnormality detection means includes an estimated value of the negative pressure consumption calculated by the negative pressure consumption calculation means, and an actual measurement value of the negative pressure consumption based on the negative pressure detection value detected by the negative pressure detection means. And detecting an abnormality in the negative pressure detecting means . The vehicle brake system according to claim 1 Symbol placement,
The abnormality detecting means does not perform abnormality detection of the negative pressure detecting means based on the estimated negative pressure value when a time change amount of the negative pressure detected value is less than a predetermined value. . The vehicle brake device according to claim 1 or 2 ,
The abnormality detection means performs the abnormality determination of the negative pressure detection means only when at least one of the negative pressure detection value, the negative pressure estimation value, the master cylinder pressure, and the wheel cylinder pressure satisfies a predetermined reference value. A vehicular brake device characterized by comprising:

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