US20140119951A1 - Failure diagnosis apparatus of brake system and failure diagnosis method of brake system - Google Patents

Failure diagnosis apparatus of brake system and failure diagnosis method of brake system Download PDF

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Publication number
US20140119951A1
US20140119951A1 US14/058,738 US201314058738A US2014119951A1 US 20140119951 A1 US20140119951 A1 US 20140119951A1 US 201314058738 A US201314058738 A US 201314058738A US 2014119951 A1 US2014119951 A1 US 2014119951A1
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United States
Prior art keywords
vacuum pump
passage
negative pressure
electric vacuum
brake system
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Abandoned
Application number
US14/058,738
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English (en)
Inventor
Katsuhiko Makino
Atsushi Sugimoto
Shota Yamanaka
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Aisan Industry Co Ltd
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Aisan Industry Co Ltd
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Publication date
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Assigned to AISAN KOGYO KABUSHIKI KAISHA reassignment AISAN KOGYO KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MAKINO, KATSUHIKO, SUGIMOTO, ATSUSHI, YAMANAKA, SHOTA
Publication of US20140119951A1 publication Critical patent/US20140119951A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B7/00—Piston machines or pumps characterised by having positively-driven valving
    • F04B7/02—Piston machines or pumps characterised by having positively-driven valving the valving being fluid-actuated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/66—Electrical control in fluid-pressure brake systems
    • B60T13/662—Electrical control in fluid-pressure brake systems characterised by specified functions of the control system components
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/66—Electrical control in fluid-pressure brake systems
    • B60T13/68—Electrical control in fluid-pressure brake systems by electrically-controlled valves
    • B60T13/683—Electrical control in fluid-pressure brake systems by electrically-controlled valves in pneumatic systems or parts thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
    • B60T17/18—Safety devices; Monitoring
    • B60T17/22—Devices for monitoring or checking brake systems; Signal devices

Definitions

  • the present invention relates to a failure diagnosis apparatus and a failure diagnosis method of a brake system including an electric vacuum pump for supplying negative pressure to a negative pressure chamber of a brake booster.
  • a negative pressure chamber of a brake booster of a brake system in a vehicle is supplied with negative pressure generated in an intake system of an engine.
  • an electric vacuum pump is placed in parallel to a main negative pressure passage for supplying negative pressure from the intake system of the engine to the negative pressure chamber of the brake booster so that the negative pressure is supplied to the negative pressure chamber of the brake booster by this electric vacuum pump.
  • Patent Document 1 discloses a technique that a discharge passage is provided to connect a discharge side of a vacuum pump to an intake system of an engine, a check valve is placed in this discharge passage and a release passage is provided to communicate a part located between the check valve and the discharge side of the vacuum pump with atmosphere, and another check valve is placed in this release passage.
  • the present invention has been made to solve the above problems and has a purpose to provide a brake system failure diagnosis apparatus and a brake system failure diagnosis method capable of diagnosing failures or malfunctions of a brake system under any circumstances.
  • one aspect of the invention provides a failure diagnosis apparatus of a brake system including: a first passage connected to a negative pressure chamber of a brake booster and an intake system of an engine; a second passage branching off from the first passage; an electric vacuum pump provided in the second passage; a first check valve for preventing a fluid from flowing from the intake system to the negative pressure chamber through the second passage; and a second check valve for preventing the fluid from flowing from the intake system to the negative pressure chamber through the first passage and preventing a fluid from flowing the intake system and a discharge port of the electric vacuum pump toward an suction port of the electric vacuum pump through the first passage; and a determination unit configured to determine functional normality of the electric vacuum pump based on a detection result of at least one of a booster internal pressure detection unit for detecting internal pressure of the negative pressure chamber and a current value detection unit for detecting an operating electric current value of the electric vacuum pump and a detection result of a pipe internal pressure detection unit for detecting internal pressure of a pipe communicated with the discharge port of the electric
  • the functional normality of the electric vacuum pump can be determined by utilizing at least one of a correlativity between the internal pressure of the pipe communicated with the discharge port of the electric vacuum pump and the internal pressure of the negative pressure chamber and a correlativity between the internal pressure of the pipe communicated with the discharge port of the electric vacuum pump and the operating electric current value of the electric vacuum pump.
  • the functional normality of the electric vacuum pump can be determined by utilizing characteristics that the operating electric current value of the electric vacuum pump and the internal pressure of the negative pressure chamber of the brake booster vary according to different internal pressure of the pipe communicated with the discharge port of the electric vacuum pump. This enables the failure diagnosis of the brake system to be executed under any circumstances.
  • the brake system further includes a changeover unit to change a connection target of the discharge port of the electric vacuum pump to either one of an intake-system-side passage communicated with the first passage and blocked off from atmosphere and an atmosphere-side passage blocked off from the first passage and communicated with atmosphere, and the pipe internal pressure detection unit is used to detect internal pressure of a pipe between the electric vacuum pump and the changeover unit.
  • the functional normality of the electric vacuum pump can be determined separately from variations in the negative pressure of the intake system by changing over the connection target of the discharge port of the electric vacuum pump to the atmosphere-side passage and utilizing the detection result of the internal pressure of the pipe between the electric vacuum pump communicated with atmosphere and the changeover unit. Therefore, correct failure diagnosis of the brake system can be performed even under any circumstances with large variations in negative pressure of the intake system. Further, the failure diagnosis of the brake system can be performed in both systems, one being established when the discharge port of the electric vacuum pump is connected to the intake-system-side passage and the other being established when the discharge port is connected to the atmosphere-side passage.
  • Another aspect of the invention to achieve the above object provides a failure diagnosis method of a brake system including: a first passage connected to a negative pressure chamber of a brake booster and an intake system of an engine; a second passage branching off from the first passage; an electric vacuum pump provided in the second passage; a first check valve for preventing a fluid from flowing from the intake system to the negative pressure chamber through the second passage; and a second check valve for preventing the fluid from flowing from the intake system to the negative pressure chamber through the first passage and preventing a fluid from flowing the intake system and a discharge port of the electric vacuum pump toward an suction port of the electric vacuum pump through the first passage; and wherein the method includes determining functional normality of the electric vacuum pump based on a detection result of at least one of internal pressure of the negative pressure chamber and an operating electric current value of the electric vacuum pump and a detection result of internal pressure of a pipe communicated with the discharge port of the electric vacuum pump.
  • the functional normality of the electric vacuum pump can be determined by utilizing at least one of a correlativity between the internal pressure of the pipe communicated with the discharge port of the electric vacuum pump and the internal pressure of the negative pressure chamber and a correlativity between the internal pressure of the pipe communicated with the discharge port of the electric vacuum pump and the operating electric current value of the electric vacuum pump.
  • the functional normality of the electric vacuum pump can be determined by utilizing characteristics that the operating electric current value of the electric vacuum pump and the internal pressure of the negative pressure chamber of the brake booster vary according to different internal pressure of the pipe communicated with the discharge port of the electric vacuum pump. This enables the failure diagnosis of the brake system to be executed under any circumstances.
  • the brake system further includes a changeover unit to change a connection target of the discharge port of the electric vacuum pump to either one of an intake-system-side passage communicated with the first passage and blocked off from atmosphere and an atmosphere-side passage blocked off from the first passage and communicated with atmosphere, and the detection result of internal pressure of the pipe communicated with the discharge port of the electric vacuum pump is a detection result of internal pressure of a pipe between the electric vacuum pump and the changeover unit.
  • the functional normality of the electric vacuum pump can be determined separately from variations in the negative pressure of the intake system by changing over the connection target of the discharge port of the electric vacuum pump to the atmosphere-side passage and utilizing the detection result of the internal pressure of the pipe between the electric vacuum pump communicated with atmosphere and the changeover unit. Therefore, correct failure diagnosis of the brake system can be performed even under any circumstances with large variations in negative pressure of the intake system. Further, the failure diagnosis of the brake system can be performed in both systems, one being established when the discharge port of the electric vacuum pump is connected to the intake-system-side passage and the other being established when the discharge port is connected to the atmosphere-side passage.
  • the brake system failure diagnosis apparatus and the brake system failure diagnosis method of the invention it is possible to diagnose failures of a brake system under any circumstances.
  • FIG. 1 is a schematic configuration view of a brake system and a failure diagnosis apparatus thereof in Example 1;
  • FIG. 2 is a block diagram showing a control system of the brake system and the failure diagnosis apparatus in Example 1;
  • FIG. 3 is a flowchart showing one example of a failure diagnosis method of the brake system in Example 1;
  • FIG. 4 is one example of a map diagram showing engine negative pressure and pump electric current value
  • FIG. 5 is a determination graph based on a pump electric current value in a case where a detection result of engine negative pressure is about ⁇ 40 kPa;
  • FIG. 6 is one example of a map diagram showing engine negative pressure and ultimate negative pressure
  • FIG. 7 is a determination graph based on a ultimate negative pressure in a case where a detection result of engine negative pressure is about ⁇ 40 kPa;
  • FIG. 8 is a flowchart showing another example of the failure diagnosis method of the brake system in Example 1;
  • FIG. 9 is a flowchart showing another example of the failure diagnosis method of the of the brake system in Example 1;
  • FIG. 10 is a schematic configuration view of a brake system and a failure diagnosis apparatus thereof in Example 2;
  • FIG. 11 is a flowchart showing one example of a failure diagnosis method of the brake system in Example 2.
  • FIG. 12 is one example of a map diagram showing engine negative pressure and pump electric current value
  • FIG. 13 is one example of a map diagram showing engine negative pressure and ultimate negative pressure
  • FIG. 14 is a flowchart showing another example of the failure diagnosis method of the brake system in Example 2.
  • FIG. 15 is a flowchart showing another example of the failure diagnosis method of the brake system in Example 2.
  • FIG. 16 is a schematic configuration view of a brake system and a failure diagnosis apparatus thereof in a modified example
  • FIG. 17 is a schematic configuration view of a brake system and a failure diagnosis apparatus thereof in another modified example.
  • FIG. 18 is a schematic configuration view of a brake system and a failure diagnosis apparatus thereof in another modified example.
  • FIG. 1 is a schematic configuration view of the brake system and the failure diagnosis apparatus thereof in Example 1.
  • FIG. 2 is a block diagram showing a control system of the brake system and the failure diagnosis apparatus in Example 1.
  • a term “negative pressure” represents a lower pressure than atmospheric pressure
  • an expression “the negative pressure is high” means that a difference from atmospheric pressure is large
  • an expression “the negative pressure is low” means that the difference from atmospheric pressure is small.
  • a brake system 1 and a failure diagnosis apparatus thereof in this example include, as shown in FIGS. 1 and 2 , a brake pedal 10 , a brake booster 12 , a master cylinder 14 , a negative pressure sensor 16 , an electric vacuum pump 18 (“electric VP” in the figures), a first check valve 20 , a second check valve 22 , an ECU 24 , a pressure detection unit 26 , and a shunt resistor 28 .
  • the brake booster 12 is provided between the brake pedal 10 and the master cylinder 14 as shown in FIG. 1 .
  • This brake booster 12 generates assist power at a predetermined boost ratio to the tread force of the brake pedal 10 .
  • the brake booster 12 is internally partitioned by a diaphragm (not shown) into separate chambers; a negative pressure chamber (not shown) connected to the master cylinder 14 and a variable pressure chamber (not shown) for introducing atmosphere.
  • the negative pressure chamber of the brake booster 12 is connected to an intake pipe 32 of an engine through a first passage L 1 .
  • the first passage L 1 is connected to the negative pressure chamber of the brake booster 12 and the intake pipe 32 . Accordingly, the negative pressure chamber of the brake booster 12 is supplied, through the first passage L 1 , with the negative pressure generated in the intake pipe 32 according to an opening degree of a throttle valve 34 during running of the engine.
  • the intake pipe 32 is one example of an “intake system” of the invention.
  • the master cylinder 14 boosts oil pressure of a brake main unit (not shown) by activation of the brake booster 12 to generate a braking force in the brake main unit.
  • the negative pressure sensor 16 is one of constituent components of the failure diagnosis apparatus of the brake system 1 and is arranged to detect the negative pressure in the negative pressure chamber of the brake booster 12 .
  • the negative pressure sensor 16 is one example of a “booster internal pressure detection unit” of the invention.
  • the electric vacuum pump 18 is provided in a second passage L 2 as shown in FIG. 1 and has a suction port 18 a connected to the negative pressure chamber of the brake booster 12 through the second passage L 2 and the first passage L 1 and a discharge port 18 b connected to the first passage L 1 via the second passage L 2 .
  • the second passage L 2 is branched off from the first passage L 1 at a point between the first check valve 20 and the second check valve 22 in the first passage L 1 and is connected to the first passage L 1 downstream of the electric vacuum pump 18 .
  • the electric vacuum pump 18 is further connected to the ECU 24 via a motor and a relay as shown in FIG. 2 . In this manner, activation of the electric vacuum pump 18 is controlled by the ECU 24 .
  • the pump 18 is started to operate in response to an activation start signal from the ECU 24 to supply negative pressure to the negative pressure chamber of the brake booster 12 from the suction port 18 a via the second passage L 2 and the first passage L 1 .
  • the electric vacuum pump 18 stops to operate in response to an operation stop signal from the ECU 24 to stop supplying negative pressure to the negative pressure chamber of the brake booster 12 from the suction port 18 a via the second passage L 2 and the first passage L 1 .
  • the first check valve 20 is provided in the first passage L 1 in a position between a joint part with the second passage L 2 and the brake booster 12 .
  • the second check valve 22 is provided in the first passage L 1 in a position closer to the intake pipe 32 than the first check valve 20 and between the joint part with the second passage L 2 and the intake pipe 32 .
  • These first check valve 20 and second check valve 22 are each configured to be opened only when the negative pressure on the side of the intake pipe 32 is higher than the negative pressure on the side of the negative pressure chamber of the brake booster 12 to allow a fluid to flow only in a direction from the side of the negative pressure chamber of the brake booster 12 to the side of the intake pipe 32 .
  • the first check valve 20 prevents air from flowing from the intake pipe 32 to the negative pressure chamber of the brake booster 12 through the second passage L 2 .
  • the second check valve 22 prevents air from flowing from the side of the intake pipe 32 to the side of the negative pressure chamber of the brake booster 12 through the first passage L 1 and also prevents air from flowing from the side of the intake pipe 32 and the side of the discharge port 18 b of the electric vacuum pump 18 toward the side of the suction port 18 a of the pump 18 through the first passage L 1 .
  • the brake system 1 in Example 1 can contain negative pressure in the negative pressure chamber of the brake booster 12 by the first check valve 20 and the second check valve 22 .
  • the ECU 24 is one of the constituent components of the failure diagnosis apparatus of the brake system 1 and is configured by a microcomputer, for example, including a ROM for storing control programs, a readable/writable RAM for storing calculation results and others, a timer, a counter, an input interface, and an output interface.
  • This ECU 24 is connected to the negative pressure sensor 16 , the electric vacuum pump 18 , the pressure detection unit 26 , the shunt resistor 28 , and others as shown in FIG. 2 .
  • the ECU 24 is also used as a “determination unit” of the invention.
  • the brake system 1 configured as above can adjust the negative pressure in the negative pressure chamber of the brake booster 12 by supplying the negative pressure generated in the intake pipe 32 to the negative pressure chamber of the brake booster 12 through the first passage L 1 .
  • the brake system 1 can also adjust the negative pressure in the negative pressure chamber of the brake booster 12 by operating (activating) the electric vacuum pump 18 to supply the negative pressure to the negative pressure chamber of the brake booster 12 through the second passage L 2 and the first passage L 1 .
  • the pressure detection unit 26 is for example a pressure sensor to detect the internal pressure in the intake pipe 32 which is a pipe communicated with the discharge port 18 b of the electric vacuum pump 18 .
  • This pressure detection unit 26 is one of the constituent components of the failure diagnosis apparatus of the brake system 1 .
  • the pressure detection unit 26 is one example of a n “pipe internal-pressure detection unit” of the invention. Instead of the pressure detection unit 26 , a pressure estimation unit (not shown) for estimating the internal pressure of the intake pipe 32 may be used.
  • the brake system 1 in Example 1 includes, as one of the constituent components of the failure diagnosis apparatus, the shunt resistor 28 serving as a resistor to detect an operating electric current value of the electric vacuum pump 18 , between the motor and the relay.
  • the information of detection results obtained by the shunt resistor 28 is transmitted to the ECU 24 .
  • This shunt resistor 28 is one example of a “current value detection unit” of the invention.
  • the functional normality of the electric vacuum pump 18 is determined from a correlativity between a detection result of the negative pressure in the intake pipe 32 (hereinafter, also referred to as “engine negative pressure”) and a detection result of an operating electric current value of the electric vacuum pump 18 (hereinafter, also referred to as a “pump electric current value”) and also a correlativity between the detection result of the engine negative pressure and a detection result of an ultimate (final) negative pressure in the negative pressure chamber of the brake booster 12 (hereinafter also simply referred to as a “ultimate negative pressure”). That is, the ECU 24 determines the functional normality of the electric vacuum pump 18 by using characteristics that the pump electric current value and the ultimate negative pressure vary according to different engine negative pressure.
  • the engine negative pressure is detected by the pressure detection unit 26 or the aforementioned pressure estimation unit (not shown), the pump electric current value is detected by the shunt resistor 28 , and the ultimate negative pressure is detected by the negative pressure sensor 26 .
  • a concrete example of the failure diagnosis method of the brake system 1 of this example will be explained below.
  • the first explanation is given to the case of determining the functional normality of the electric vacuum pump 18 based on both the correlativity between the detection result of engine negative pressure and the detection result of pump electric current value and the correlativity between the detection result of engine negative pressure and the detection result of ultimate negative pressure.
  • the ECU 24 periodically executes a control routine shown in FIG. 3 at a predetermined time interval.
  • the failure diagnosis method of the brake system 1 which will be explained below is supposed to be performed under a condition that a system detection condition is established by turn-on of an ignition switch of a vehicle or the like.
  • the ECU 24 Upon start of the processing of the routine shown in FIG. 3 , the ECU 24 first activates (turns ON) the electric vacuum pump 18 (step S 1 ) and detects the engine negative pressure by the pressure detection unit 26 (step S 2 ). The ECU 24 decides a determination value used to determine the functional normality of the electric vacuum pump 18 based on the detection result of engine negative pressure (step S 3 ). To be concrete, based on the detection result of engine negative pressure, a predetermined lower limit and a predetermined upper limit of the pump electric current value and a determination value of the ultimate negative pressure are decided. For this purpose, herein, for example, map diagrams shown in FIGS. 4 and 6 which will be mentioned later are used.
  • the ECU 24 determines whether or not the pump electric current value is equal to or higher than the predetermined lower limit (step S 4 ). If YES in step S 4 , the ECU 24 determines whether or not the pump electric current value is equal to or lower than the predetermined upper limit (step S 5 ).
  • step S 5 the ECU 24 determines whether the brake pedal 10 is additionally depressed (i.e., whether the brake is turned ON) (step S 6 ). If YES in step S 6 , the ECU 24 terminates this routine immediately.
  • the ECU 24 determines whether a predetermined time has passed from the time when the electric vacuum pump 18 is started to operate (step S 7 ).
  • the predetermined time is a time required until the negative pressure in the negative pressure chamber of the brake booster 12 reaches a target negative pressure value.
  • step S 8 the ECU 24 determines whether or not the ultimate negative pressure is equal to or less than the determination value. Specifically, the ECU 24 determines whether or not the ultimate negative pressure is equal to a predetermined negative pressure value (the determination value in FIG. 6 ) or whether or not the ultimate negative pressure is higher than the predetermined negative pressure value (the determination value in FIG. 6 ).
  • step S 9 the ECU 24 determines that the function of the electric vacuum pump 18 is normal. In other words, if the ultimate negative pressure is equal to or higher than the predetermined negative pressure value, the ECU 24 determines that the function of the electric vacuum pump 18 is normal.
  • step S 10 determines that the function of the electric vacuum pump 18 is abnormal (step S 10 ).
  • This example uses a map diagram shown in FIG. 4 , for example, showing the engine negative pressure (a horizontal axis in FIG. 4 ) and the pump electric current value (a vertical axis in FIG. 4 ). Further, this example uses a map diagram shown in FIG. 6 , for example, showing the engine negative pressure (a horizontal axis in FIG. 6 ) and the ultimate negative pressure (a vertical axis in FIG. 6 ).
  • a normal range of the pump electric current value ranges from a lower limit of about 4.3 A to an upper limit of about 5.0 A from FIG. 4 and a determination value of the ultimate negative pressure is thus about ⁇ 90.5 kPa from FIG. 6 .
  • a detection result of the engine negative pressure is about ⁇ 40 kPa, therefore, if the detection result of the pump electric current value is within the normal range (in a range of about 4.3 A or more and about 5.0 A or less) shown in FIG. 4 as indicated in FIG. 5 and the detection result of the ultimate negative pressure is equal to the determination value (about ⁇ 90.5 kPa) shown in FIG. 6 as indicated in FIG.
  • a vertical axis in FIG. 5 represents the engine negative pressure and a vertical axis in FIG. 7 represents the engine negative pressure and the ultimate negative pressure.
  • the ECU 24 determines that the electric vacuum pump 18 is functioning abnormally.
  • the failure diagnosis method of the brake system 1 of this example may be configured to determine the functional normality of the electric vacuum pump 18 only from the correlativity between the detection result of engine negative pressure and the detection result of pump electric current value as shown in FIG. 8 .
  • the ECU 24 periodically executes the control routine shown in FIG. 8 at predetermined time intervals.
  • the ECU 24 Upon start of the processing of the routine in FIG. 8 , the ECU 24 first activates (turns ON) the electric vacuum pump 18 (step S 11 ) and detects the engine negative pressure (step S 12 ). The ECU 24 then decides a determination value used to determine the functional normality of the electric vacuum pump 18 based on the detection result of engine negative pressure (step S 13 ). To be concrete, based on the detection result of engine negative pressure, a predetermined lower limit and a predetermined upper limit of the pump electric current are decided.
  • step S 14 determines that the pump electric current value is equal to or higher than the predetermined lower limit (step S 14 : YES) and if the pump electric current value is equal to or lower than the predetermined upper limit (step 15 : YES), the ECU 24 determines that the function of the electric vacuum pump 18 is normal (step S 16 ). On the other hand, if the pump electric current value is less than the predetermined lower limit (step S 14 : NO) or if the pump electric current value is larger than the predetermined upper limit (step S 15 : NO), the ECU 24 determines that the function of the electric vacuum pump 18 is abnormal (step S 17 ).
  • the failure diagnosis method of the brake system 1 of this example may be configured to determine the functional normality of the electric vacuum pump 18 only from the correlativity between the detection result of engine negative pressure and the detection result of ultimate negative pressure shown in FIG. 9 .
  • the ECU 24 periodically executes the control routine shown in FIG. 9 at predetermined time intervals.
  • the ECU 24 Upon start of the processing of the routine shown in FIG. 9 , the ECU 24 first activates (turns ON) the electric vacuum pump 18 (step S 21 ) and detects engine negative pressure (step S 22 ). The ECU 24 then decides a determination value of ultimate negative pressure based on the detection result of engine negative pressure (step S 23 ). In the case where the brake pedal 10 is not additionally depressed (the brake is not turned ON) (step S 24 : NO) and a predetermined time has passed from the time when the electric vacuum pump 18 is started to operate (step S 25 : YES), if the ultimate negative pressure is equal to or lower than the determination value (step S 26 : YES), the ECU 24 determines the function of the electric vacuum pump 18 is normal (step S 27 ).
  • step S 28 the ECU 24 determines that the function of the electric vacuum pump 18 is abnormal.
  • the functional normality of the electric vacuum pump 18 is determined by use of at least one of the correlativity between the internal pressure of the intake pipe 32 and the internal pressure of the negative pressure chamber of the brake booster 12 and the correlativity between the internal pressure of the intake pipe 32 and the operating electric current value of the electric vacuum pump 18 .
  • the ECU 24 determines the functional normality of the electric vacuum pump 18 by utilizing the characteristics that the pump electric current value and the ultimate negative pressure vary according to different engine negative pressure. Therefore, even when the engine negative pressure varies according to a running condition of an engine, it is possible to determine the functional normality of the electric vacuum pump 18 . Accordingly, the failure diagnosis of the brake system 1 can be performed under any circumstances.
  • Example 2 a brake system 2 and a failure diagnosis apparatus thereof are configured as shown in FIG. 10 .
  • the brake system 2 differs from the brake system 1 in that a changeover valve 30 is provided in the second passage L 2 and connected to the discharge port 18 b of the electric vacuum pump 18 .
  • the changeover valve 30 is a changeover unit to change a connection target of the discharge port 18 b of the electric vacuum pump 18 to either one of an intake-system-side passage LA and an atmosphere-side passage LB.
  • the intake-system-side passage LA is a passage communicated with the first passage L 1 and blocked from atmosphere
  • the atmosphere-side passage LB is a passage blocked from the first passage L 1 and communicated with atmosphere.
  • the activation of the changeover valve 30 is controlled by the ECU 24 .
  • the changeover valve 30 is configured to connect the discharge port 18 b of the electric vacuum pump 18 to the intake-system-side passage LA during non-energization (non-operation) and alternatively connect the discharge port 18 b of the pump 18 to the atmosphere-side passage LB during energization (operation).
  • Concrete examples of the changeover valve 30 may include an electromagnetic type three-way valve and others.
  • the pressure detection unit 26 detects the internal pressure of a pipe (a part of the second passage L 2 ) (hereinafter, also referred to as “discharge-port negative pressure”) between the discharge port 18 b of the electric vacuum pump 18 and the changeover valve 30 .
  • the changeover valve 30 is first changed to communicate with atmosphere (step S 31 ). Specifically, the changeover 30 changes the connection target of the discharge port 18 b of the electric vacuum pump 18 from the intake-system-side passage LA to the atmosphere-side passage LB. While the discharge port 18 b of the pump 18 is connected to the atmosphere-side passage LB in this way, the processing in steps S 32 to S 41 is executed. The details of the processing in steps S 32 to S 41 are the same as those of the processing in steps S 1 to S 10 shown in FIG.
  • the ECU 24 determines the functional normality of the pump 18 from the correlativity between a detection result of the discharge-port negative pressure and a detection result of the pump electric current value and the correlativity between the detection result of the discharge-port negative pressure and a detection result of the ultimate negative pressure.
  • FIG. 12 uses a map diagram shown in FIG. 12 , for example, showing the discharge-port negative pressure (a horizontal axis in FIG. 12 ) and the pump electric current value (a vertical axis in FIG. 12 ). Further, this example uses a map diagram shown in FIG. 13 , for example, showing the discharge-port negative pressure (a horizontal axis in FIG. 13 ) and the ultimate negative pressure (a vertical axis in FIG. 13 ).
  • a normal range of the pump electric current value ranges from a lower limit of about 5.75 A to an upper limit of about 6.75 A from FIG. 12 and a determination value of the ultimate negative pressure is about ⁇ 83 kPa from FIG. 13 .
  • the discharge port 18 b of the electric vacuum pump 18 is connected to the atmosphere-side passage LB and the discharge-port negative pressure is 0 kPa, therefore, if the detection result of the pump electric current value is within the normal range (in a rage of about 5.75 A or more and about 6.75 A or less) shown in FIG. 12 and the detection result of the ultimate negative pressure is equal to or higher than the determination value (about ⁇ 83 kPa) shown in FIG. 13 (i.e., if the negative pressure is a value on the determination value in FIG. 13 or a value located below the determination value in FIG. 13 ), the ECU 24 determines that the function of the electric vacuum pump 18 is normal.
  • the ECU 24 determines the function of the electric vacuum pump 18 is abnormal.
  • the failure diagnosis method of the brake system 2 shown in FIG. 11 is configured to make determination of the functional normality of the electric vacuum pump 18 by changing over the connection target of the discharge port 18 b of the electric vacuum pump 18 to the atmosphere-side passage LB, irrespective of the running status of an engine. Accordingly, it is possible to determine the functional normality of the electric vacuum pump 18 under stable conditions not affected by variations in engine negative pressure.
  • the failure diagnosis method of the brake system 2 of this example can also make determination of the functional normality of the electric vacuum pump 18 only from the correlativity between the detection result of the discharge-port negative pressure and the detection result of the pump electric current value as indicated in FIG. 14 .
  • the ECU 24 periodically executes the control routine shown in FIG. 14 at predetermined time intervals.
  • the ECU 24 Upon start of the processing in the routine shown in FIG. 14 , the ECU 24 first causes the changeover valve 30 to communicate with atmosphere (step S 51 ). Specifically, the changeover valve 30 changes the connection target of the discharge port 18 b of the electric vacuum pump 18 from the intake-system-side passage LA to the atmosphere-side passage LB. While the discharge port 18 b of the pump 18 is connected to the atmosphere-side passage LB in this way, the processing in steps S 52 to S 58 is executed. The details of the processing in steps S 52 to S 58 are the same as those in the processing in steps S 11 to S 17 in FIG. 8 .
  • the ECU 24 makes determination of the functional normality of the electric vacuum pump 18 from the correlativity between the detection result of the discharge-port negative pressure and the detection result of the pump electric current value.
  • the failure diagnosis method of the brake system 2 of this example also may be configured to determine the functional normality of the electric vacuum pump 18 only from the correlativity between the detection result of the discharge-port negative pressure and the detection result of the ultimate negative pressure as shown in FIG. 15 .
  • the ECU 24 periodically the control routine shown in FIG. 15 at predetermined time intervals.
  • the ECU 24 first causes the changeover valve 30 to communicate with atmosphere (step S 61 ). Specifically, the changeover valve 30 changes the connection target of the discharge port 18 b of the electric vacuum pump 18 from the intake-system-side passage LA to the atmosphere-side passage LB. While the discharge port 18 b of the pump 18 is connected to the atmosphere-side passage LB in this way, the processing in steps S 62 to S 69 is executed. The details of the processing in steps S 62 to S 69 are the same as those in the processing in steps S 21 to S 28 in FIG. 9 . The ECU 24 makes determination of the functional normality of the electric vacuum pump 18 from the correlativity between the detection result of the discharge-port negative pressure and the detection result of the ultimate negative pressure.
  • the failure diagnosis method of the brake system 2 may also be configured to determine the functional normality of the electric vacuum pump 18 without causing the changeover valve 30 to communicate with atmosphere, that is, by holding the discharge port 18 b of the pump 18 connected to the intake-system-side passage LA though the changeover valve 30 .
  • the functional normality of the electric vacuum pump 18 is determined by using at least one of the correlativity between the internal pressure of the pipe located between the discharge port 18 b of the pump 18 and the changeover valve 30 and the operating electric current value of the pump 18 and the correlativity between the internal pressure of the pipe located between the discharge port 18 b of the pump 18 and the changeover valve 30 and the internal pressure of the negative pressure chamber of the brake booster 12 .
  • the ECU 24 determines the functional normality of the electric vacuum pump 18 by utilizing the characteristics that the pump electric current value and the ultimate negative pressure vary according to different discharge-port negative pressure.
  • connection target of the discharge port 18 b of the electric vacuum pump 18 is changed to the atmosphere-side passage LB by the changeover valve 30 , so that the discharge-port negative pressure becomes atmospheric pressure and is not affected by the engine negative pressure.
  • This can make determination of the functional normality of the electric vacuum pump 18 separately from variations in engine negative pressure.
  • the brake system 2 can be subjected to correct failure diagnosis even when the engine negative pressure largely varies.
  • the failure diagnosis of the brake system 2 can be achieved in both systems, one being established when the discharge port 18 b of the electric vacuum pump 18 is connected to the intake-system-side passage LA and the other being established when the discharge port 18 b is connected to the atmosphere-side passage LB.
  • One modified example may be configured as a brake system 3 shown in FIG. 16 .
  • This brake system 3 differs from the brake system 1 in that a third check valve 36 is provided in the second passage L 2 on the side of the discharge port 18 b of the electric vacuum pump 18 .
  • the third check valve 36 prevents air from flowing from the intake pipe 32 to the negative pressure of the brake booster 12 through the second passage L 2 .
  • Another modified example may be configured as a brake system 4 shown in FIG. 17 .
  • This brake system 4 differs from the brake system 2 in that the first check valve 20 is provided in the second passage L 2 on the side of the discharge port 18 b of the electric vacuum pump 18 .
  • the first check valve 20 prevents air from flowing from the intake pipe 32 to the negative pressure chamber of the brake booster 12 through the second passage L 2 .
  • the first check valve 20 or the third check valve 36 is provided in the second passage L 2 on the side of the discharge port 18 b of the electric vacuum pump 18 . Accordingly, even after the electric vacuum pump 18 is stopped to operate, the inside of the pump 18 and the inside of the second passage L 2 are kept at negative pressure. This can provide an assist effect to operation of the electric vacuum pump 18 (an effect of reducing drive torque) at the time of restart of operation of the pump 18 .
  • the brake systems 3 and 4 of the modified examples can perform the failure diagnosis method similar to the failure diagnosis method of the brake systems 1 and 2 and provide the same effects as the brake systems 1 and 2 .
  • Still another modified example may be configured as a brake system 5 shown in FIG. 18 .
  • This brake system 5 differs from the brake system 2 in that the first check valve 20 is provided in the second passage L 2 on the side of the suction port 18 a of the electric vacuum pump 18 .
  • the first check valve 20 prevents air from flowing from the intake pipe 32 to the negative pressure chamber of the brake booster 12 through the second passage L 2 .
  • the brake system 5 of this modified example can perform the failure diagnosis method similar to the failure diagnosis method of the brake system 2 and provide the same effects as the brake system 2 .
  • Reference Sings List 1 to 5 Brake system, 10: Brake pedal, 12: Brake booster, 14: Master cylinder, 16: Negative pressure sensor, 18: Electric vacuum pump (Electric VP), 18a: Suction port, 18b: Discharge port, 20: First check valve, 22: Second check valve, 24: ECU 26: Pressure detection unit, 28: Shunt resistor, 30: Changeover valve, 32: Intake pipe, 34: Throttle valve, 36: Third check valve, L1: First passage, L2: Second passage, LA: Intake-system-side passage, LB: Atmosphere-side passage

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transportation (AREA)
  • General Engineering & Computer Science (AREA)
  • Valves And Accessory Devices For Braking Systems (AREA)
US14/058,738 2012-10-26 2013-10-21 Failure diagnosis apparatus of brake system and failure diagnosis method of brake system Abandoned US20140119951A1 (en)

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JP2012-236478 2012-10-26
JP2012236478A JP2014084055A (ja) 2012-10-26 2012-10-26 ブレーキシステムの故障診断装置及びブレーキシステムの故障診断方法

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CN107867281A (zh) * 2016-09-28 2018-04-03 福特全球技术公司 真空系统的故障诊断方法
CN110300687A (zh) * 2017-03-06 2019-10-01 日立汽车系统株式会社 助力装置的异常诊断装置及异常诊断方法

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CN106153313B (zh) * 2015-04-27 2018-04-13 北京福田康明斯发动机有限公司 一种发动机辅助制动系统的故障检测方法及检测装置
CN104931825A (zh) * 2015-06-13 2015-09-23 复旦大学 一种用于器件光学和电学测量以及真空监测的集成设备
JP6193937B2 (ja) * 2015-08-27 2017-09-06 ファナック株式会社 分流器の故障を検出する機能を有するモータ駆動装置
JP6747646B2 (ja) * 2016-11-29 2020-08-26 日立オートモティブシステムズ株式会社 負圧センサの故障診断装置、負圧センサの故障診断方法およびブレーキ装置
CN110824224B (zh) * 2019-08-01 2021-12-07 中国第一汽车股份有限公司 一种电动汽车电动助力系统的检测装置及其检测方法
CN113654576B (zh) * 2021-07-02 2023-12-19 华人运通(江苏)技术有限公司 一种基于水泵电流的四通阀位置识别方法及系统

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US20170106847A1 (en) * 2015-10-14 2017-04-20 Ford Global Technologies, Llc Method and System For Actuating A Vacuum Pump Associated With A Brake Booster
US10160432B2 (en) * 2015-10-14 2018-12-25 Ford Global Technologies, Llc Method and system for actuating a vacuum pump associated with a brake booster
CN107867281A (zh) * 2016-09-28 2018-04-03 福特全球技术公司 真空系统的故障诊断方法
CN110300687A (zh) * 2017-03-06 2019-10-01 日立汽车系统株式会社 助力装置的异常诊断装置及异常诊断方法

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