JP7266954B2 - Negative pressure supply system - Google Patents

Description

The present invention relates to a negative pressure supply system that supplies negative pressure to a brake booster.

2. Description of the Related Art Conventionally, a brake booster for assisting brake operation is known. The brake booster accumulates negative pressure in a negative pressure chamber and uses the negative pressure to amplify the force applied to the brake pedal by the driver. When the brake booster is used by braking, the negative pressure accumulated in the negative pressure chamber is reduced. In the brake booster, the negative pressure in the negative pressure chamber is controlled within a predetermined range by the negative pressure supply system. The negative pressure supply system detects the negative pressure in the negative pressure chamber, causes the negative pressure supply source to supply negative pressure when the detected negative pressure drops to the lower threshold, and supplies negative pressure when the detected negative pressure rises to the upper threshold. Stop supplying negative pressure to the source. In this specification, when the negative pressure is close to the atmospheric pressure, it is expressed as "small negative pressure", and when the negative pressure is far from the atmospheric pressure, it is expressed as "large negative pressure".

If the negative pressure cannot be detected accurately, the negative pressure cannot be properly controlled. A negative pressure supply system has been proposed that has two systems of sensors for detecting negative pressure in case of failure. Patent Literature 1 discloses a braking booster having two systems of pressure detection units. The brake booster determines failure of the pressure detection units and identifies the failed pressure detection unit based on the negative pressure detected by each pressure detection unit. The brake booster identifies the failed pressure detector based on the change in the negative pressure detected by each pressure detector with respect to the operation of the brake pedal. Further, when the brake pedal is not operated, the brake booster drives the electric vacuum pump for a set period of time, and based on the change in the negative pressure detected by each pressure detection unit due to the drive, the failed pressure is detected. part is specified.

Patent No. 5799844

In the invention disclosed in Patent Document 1, when the brake pedal is not operated, the electric vacuum pump is forcibly driven regardless of the actual negative pressure of the brake booster. The unnecessary drive generates operating noise and shortens the life of the electric vacuum pump. Further, until the failed pressure detector is identified, the driving of the electric vacuum pump may be controlled based on the negative pressure detected by the failed pressure detector. In this case, if control is performed based on a negative pressure that is higher than the actual negative pressure, the electric vacuum pump will not be driven even if the actual negative pressure falls below the lower limit threshold, and the negative pressure of the brake booster will continue to drop. Become.

SUMMARY OF THE INVENTION The present invention has been devised under the circumstances described above. The object is to provide a negative pressure supply system that can be controlled to

In order to solve the above problems, the present invention takes the following technical measures.

A negative pressure supply system provided by the present invention is a negative pressure supply system that supplies negative pressure to a negative pressure chamber of a brake booster, comprising a negative pressure supply source, a control device that controls the negative pressure supply source, A first negative pressure detection section and a second negative pressure detection section are provided for respectively detecting negative pressure in the negative pressure chamber, and the control device detects the first negative pressure detected by the first negative pressure detection section and the first negative pressure detected by the first negative pressure detection section. 2. When the negative pressure for comparison based on the second negative pressure detected by the negative pressure detection unit is equal to or lower than the lower limit threshold, the negative pressure supply source is driven, and when the negative pressure for comparison is equal to or higher than the upper threshold, a negative pressure control unit that stops the negative pressure supply source; and a failure determination unit that determines occurrence of a failure based on the first negative pressure and the second negative pressure, wherein the negative pressure control unit includes the When the failure determination unit determines that a failure has occurred, the negative pressure supply source is driven when the first negative pressure or the second negative pressure becomes equal to or less than the lower limit threshold value, and the first negative pressure or the The negative pressure supply source is stopped when the second negative pressure exceeds the upper threshold value.

In a preferred embodiment of the present invention, the negative pressure control section sets the lower limit threshold to the difference between the first negative pressure and the second negative pressure when the failure determination section determines that a failure has occurred. Alternatively, the upper threshold is changed to a temporary upper threshold that is reduced based on the difference between the first negative pressure and the second negative pressure, and the comparative negative Compare with pressure.

According to the present invention, when a failure occurs, the negative pressure control unit drives the negative pressure supply source when the first negative pressure or the second negative pressure becomes equal to or lower than the lower limit threshold, and the first negative pressure or the second negative pressure is equal to or greater than the upper limit threshold, the negative pressure supply source is stopped. Therefore, the negative pressure control section can appropriately control the negative pressure supply source from the occurrence of the failure until the failure is identified. Also, there is no need to drive the negative pressure supply unnecessarily.

Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

1 is a schematic block diagram showing the configuration of a vehicle to which a negative pressure supply system according to a first embodiment is applied; FIG. It is a figure for demonstrating a 1st negative pressure and a 2nd negative pressure. 6 is an example of a flowchart for explaining negative pressure detection processing performed by a negative pressure detection unit of the control device; (a) is an example of a flowchart for explaining a failure identifying process performed by a failure identifying section, and (b) is an example of a flowchart for describing a negative pressure control process performed by a negative pressure control section. 4 is a time chart showing changes in negative pressure and drive states of negative pressure pumps when a failure occurs. FIG. 10 is a time chart showing changes in negative pressure and drive states of negative pressure pumps when a failure occurs in a modified example; FIG. 10 is an example of a flowchart for explaining negative pressure detection processing of the negative pressure supply system according to the second embodiment; 9 is an example of a flowchart for explaining negative pressure control processing of the negative pressure supply system according to the second embodiment; 9 is a time chart showing changes in negative pressure and drive states of negative pressure pumps when a failure occurs in the second embodiment; FIG. 11 is a schematic block diagram showing the configuration of a vehicle to which a negative pressure supply system according to a third embodiment is applied;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

<First embodiment>
FIG. 1 is a schematic block diagram showing the configuration of a vehicle 1 to which a negative pressure supply system according to the first embodiment is applied. As shown in FIG. 1 , the vehicle 1 comprises a brake booster 9 , an on-board bus 8 and a vacuum supply system 2 . Although the vehicle 1 has other configurations, they are omitted in FIG.

The brake booster 9 is a device for assisting the driver's braking operation, and by utilizing the negative pressure accumulated in the negative pressure chamber 91, it amplifies the force applied to the brake pedal 95 by the driver. The brake booster 9 utilizes negative pressure supplied from the negative pressure supply system 2 . The brake booster 9 may further include a negative pressure tank connected to the negative pressure chamber 91 for accumulating negative pressure.

The vehicle-mounted bus 8 is a communication line for each ECU (Electronic Control Unit) mounted on the vehicle 1 to communicate. Each ECU and the like perform two-way communication via an in-vehicle bus 8 according to a CAN (Controller Area Network) communication protocol. In addition, the communication protocol used by the vehicle-mounted bus 8 is not limited.

The negative pressure supply system 2 is a mechanism for adjusting the negative pressure of the brake booster 9 . The negative pressure supply system 2 includes a negative pressure pump 3 , a control device 4 , a first atmospheric pressure sensor 5 , a signal line 51 , a second atmospheric pressure sensor 6 and an atmospheric pressure sensor 7 .

The negative pressure pump 3 is a device that pressurizes and discharges air. The negative pressure pump 3 is an electric pump and is powered by a battery (not shown). The negative pressure pump 3 may be a mechanical pump driven by power transmitted from wheels or an internal combustion engine. The negative pressure pump 3 has an intake port and an exhaust port. When driven, the negative pressure pump 3 pressurizes the air sucked from the intake port and discharges it from the exhaust port. An intake port of the negative pressure pump 3 is connected to a negative pressure chamber 91 of the brake booster 9 via a pipe 31 . Therefore, when the negative pressure pump 3 is driven, the air in the negative pressure chamber 91 is discharged, so the negative pressure of the brake booster 9 increases. Although not shown, the pipe 31 is provided with a check valve for preventing air from being supplied to the negative pressure chamber 91 when the negative pressure pump 3 is not driven. The check valve permits the supply of air from the negative pressure chamber 91 to the suction port of the negative pressure pump 3 and blocks the supply of air from the suction port of the negative pressure pump 3 to the negative pressure chamber 91 . Driving of the negative pressure pump 3 is controlled by the control device 4 . The negative pressure pump 3 corresponds to the "negative pressure supply source" of the present invention.

The first atmospheric pressure sensor 5 is attached to the negative pressure chamber 91 of the brake booster 9 and detects the atmospheric pressure (first negative pressure) in the negative pressure chamber 91 based on the atmospheric pressure. The first atmospheric pressure sensor 5 is a so-called relative pressure sensor (gauge pressure sensor), and is an atmospheric pressure sensor that detects the atmospheric pressure based on the atmospheric pressure. The first atmospheric pressure sensor 5 outputs a detection signal corresponding to the first negative pressure. The detection signal is input to the control device 4 via the signal line 51 .

The second atmospheric pressure sensor 6 is attached to the negative pressure chamber 91 of the brake booster 9 and detects the atmospheric pressure (absolute pressure) in the negative pressure chamber 91 based on the absolute vacuum. The second atmospheric pressure sensor 6 is a so-called absolute pressure sensor that detects atmospheric pressure based on absolute vacuum. The second atmospheric pressure sensor 6 outputs a detection signal corresponding to the absolute pressure inside the negative pressure chamber 91 . The detection signal is input to the control device 4 via the vehicle bus 8 .

The atmospheric pressure sensor 7 is arranged outside the brake booster 9 and detects the atmospheric pressure. The mounting position of the atmospheric pressure sensor 7 is not limited. The atmospheric pressure sensor 7 is a so-called absolute pressure sensor that detects atmospheric pressure based on absolute vacuum. The atmospheric pressure sensor 7 outputs a detection signal corresponding to atmospheric pressure. The detection signal is input to the control device 4 via the vehicle bus 8 . The atmospheric pressure sensor 7 does not have to be dedicated to the negative pressure supply system 2, and the atmospheric pressure sensor 7 used for estimating altitude, for example, may be used. In this case, the atmospheric pressure acquired by another ECU based on the detection signal of the atmospheric pressure sensor 7 may be input to the control device 4 .

The control device 4 is an ECU that controls the negative pressure supply system 2 and controls the negative pressure of the brake booster 9 by controlling the drive of the negative pressure pump 3 . The control device 4 may be a dedicated ECU or an ECU having other control functions.

The control device 4 receives a detection signal corresponding to the first negative pressure detected by the first atmospheric pressure sensor 5 via the signal line 51 . In addition, the control device 4 outputs a detection signal corresponding to the absolute pressure in the negative pressure chamber 91 detected by the second atmospheric pressure sensor 6 and an atmospheric pressure detected by the atmospheric pressure sensor 7 via the vehicle bus 8. A detection signal is input. The control device 4 includes a negative pressure detection section 41 and a negative pressure control section 44 as functional components.

The negative pressure detector 41 detects the negative pressure of the brake booster 9 . The negative pressure detector 41 acquires the first negative pressure P1 based on the detection signal input from the first atmospheric pressure sensor 5 . Further, the negative pressure detection unit 41 obtains the second negative pressure P2 based on the detection signal input from the second atmospheric pressure sensor 6 and the detection signal input from the atmospheric pressure sensor 7 . The second negative pressure P2 is the differential pressure between the atmospheric pressure and the pressure (absolute pressure) in the negative pressure chamber 91 . That is, the negative pressure detection unit 41 acquires the atmospheric pressure (absolute pressure) in the negative pressure chamber 91 based on the detection signal input from the second atmospheric pressure sensor 6, and detects the detection signal input from the atmospheric pressure sensor 7. Based on, get the atmospheric pressure. Then, the negative pressure detection unit 41 calculates the second negative pressure P2 by subtracting the air pressure (absolute pressure) inside the negative pressure chamber 91 from the atmospheric pressure. The negative pressure detection unit 41 outputs either the first negative pressure P1 or the second negative pressure P2 to the negative pressure control unit 44 as the negative pressure of the brake booster 9 (comparative negative pressure P). A combination of the first atmospheric pressure sensor 5 and the negative pressure detection section 41 corresponds to the "first negative pressure detection section" of the present invention. A combination of the second atmospheric pressure sensor 6, the atmospheric pressure sensor 7, and the negative pressure detection section 41 corresponds to the "second negative pressure detection section" of the present invention.

FIG. 2 is a diagram for explaining the first negative pressure P1 and the second negative pressure P2. The first negative pressure P1 is the pressure in the negative pressure chamber 91 detected by the first pressure sensor 5 and based on the atmospheric pressure. The second negative pressure P2 is the differential pressure between the atmospheric pressure (absolute pressure) in the negative pressure chamber 91 based on the absolute vacuum detected by the second atmospheric pressure sensor 6 and the atmospheric pressure detected by the atmospheric pressure sensor 7. .

As shown in FIG. 1 , the negative pressure detection section 41 includes a failure determination section 42 and a failure identification section 43 .

The failure determination unit 42 is a functional block that determines whether or not any one of the first atmospheric pressure sensor 5, the second atmospheric pressure sensor 6, and the atmospheric pressure sensor 7 has failed. When none of the first atmospheric pressure sensor 5, the second atmospheric pressure sensor 6, and the atmospheric pressure sensor 7 is malfunctioning, the first negative pressure P1 and the second negative pressure P2 are approximately the same value. Using this fact, the failure determination unit 42 determines whether or not there is a failure depending on whether the first negative pressure P1 and the second negative pressure P2 are approximately the same value. Specifically, when the negative pressure difference ΔP (=|P1−P2|), which is the absolute value of the difference between the first negative pressure P1 and the second negative pressure P2, is equal to or less than the determination threshold, It is determined that the first negative pressure P1 and the second negative pressure P2 are substantially the same value, and that neither of them is out of order. Considering the detection errors of the first atmospheric pressure sensor 5, the second atmospheric pressure sensor 6, and the atmospheric pressure sensor 7, the determination threshold value is determined when the first negative pressure P1 and the second negative pressure P2 are substantially the same. A value that can be determined is appropriately set. FIG. 2(a) shows a case where the negative pressure difference ΔP is sufficiently small and equal to or lower than the judgment threshold, and neither of them is out of order. On the other hand, when the negative pressure difference ΔP is greater than the determination threshold, the failure determination unit 42 determines that the first negative pressure P1 and the second negative pressure P2 are different, and determines that one of them is out of order. FIG. 2(b) shows a case where the negative pressure difference ΔP is large and larger than the judgment threshold, and one of them is out of order. In addition, the determination method by the failure determination part 42 is not limited.

When the failure determination unit 42 determines that none of them are out of order, the negative pressure detection unit 41 outputs, for example, the first negative pressure P1 as the negative pressure P for comparison to the negative pressure control unit 44 . On the other hand, if the failure determining unit 42 determines that one of them is malfunctioning, the failure identifying unit 43 determines which one is malfunctioning (whether the first atmospheric pressure sensor 5 is malfunctioning, the second atmospheric pressure sensor 6 or the atmospheric pressure is the sensor 7 faulty). The negative pressure detection unit 41 outputs the correct one of the first negative pressure P1 and the second negative pressure P2 (the one detected by the non-malfunctioning sensor) to the negative pressure control unit 44 as the negative pressure P for comparison. Output. In addition, the negative pressure detection unit 41 notifies the driver of the failure information identified by the failure identification unit 43 by outputting the failure information to a device (a monitor or a display lamp) that can notify the driver or to an ECU that controls the same. do.

In the present embodiment, during the failure identification period from when the failure determination unit 42 determines that one of them is malfunctioning to when the failure identification unit 43 identifies which one is malfunctioning, the negative pressure detection unit 41 For example, the first negative pressure P1 is output to the negative pressure controller 44 as the negative pressure P for comparison. Further, the negative pressure detection unit 41 changes the upper limit threshold value P _off or the lower limit threshold value P _on (described later) of the negative pressure control unit 44 during the failure identification period. When the first negative pressure P1 is higher than the second negative pressure P2, the negative pressure detection unit 41 changes the lower limit threshold value P _on to a provisional lower limit threshold value P _on ′ increased by the negative pressure difference ΔP. On the other hand, when the first negative pressure P1 is lower than the second negative pressure P2, the negative pressure detection unit 41 changes the upper threshold value P _off to a provisional upper threshold value P _off ' reduced by the negative pressure difference ΔP.

FIG. 3 is an example of a flowchart for explaining the negative pressure detection process performed by the negative pressure detection unit 41 of the control device 4. As shown in FIG. The negative pressure detection process is performed at regular intervals while the start switch (ignition key switch) of the vehicle 1 is turned on.

First, the first negative pressure P1 and the second negative pressure P2 are detected (S1). Specifically, the negative pressure detection section 41 acquires the first negative pressure P1 based on the detection signal input from the first atmospheric pressure sensor 5 . Further, the negative pressure detection unit 41 acquires the atmospheric pressure based on the detection signal input from the atmospheric pressure sensor 7, and detects the pressure in the negative pressure chamber 91 based on the detection signal input from the second atmospheric pressure sensor 6. (absolute pressure). Then, the negative pressure detection unit 41 calculates the second negative pressure P2 by subtracting the air pressure (absolute pressure) inside the negative pressure chamber 91 from the atmospheric pressure.

Next, a negative pressure difference ΔP is calculated from the first negative pressure P1 and the second negative pressure P2 (S2). Specifically, the negative pressure detection unit 41 calculates the absolute value of the difference between the first negative pressure P1 and the second negative pressure P2, and defines the calculated result as the negative pressure difference ΔP. Next, the failure determination unit 42 compares the negative pressure difference ΔP with the determination threshold value P0 (S3). If the negative pressure difference ΔP is equal to or less than the determination threshold value P0 (S3: YES), it is determined that none of them are out of order, the first negative pressure P1 is output (S4), and the negative pressure detection process ends. Specifically, the negative pressure detection unit 41 outputs the first negative pressure P1 to the negative pressure control unit 44 as the negative pressure P for comparison.

On the other hand, if the negative pressure difference ΔP is greater than the determination threshold value P0 (S3: NO), it is determined that one of them has failed, and failure identification processing is started (S5). Specifically, the failure identification unit 43 starts failure identification processing to identify which one has failed. The failure identification process is executed independently of the negative pressure detection process. Therefore, the negative pressure detection process proceeds even while the failure identification process is being executed without waiting for the failure identification process to end. An example of failure identification processing performed by the failure identification unit 43 will be described later. Next, the first negative pressure P1 and the second negative pressure P2 are compared (S6), and if the first negative pressure P1 is greater than the second negative pressure P2 (S6: YES), the lower limit threshold value P _on is changed, When the first negative pressure P1 is lower than the second negative pressure P2 (S6: NO), the upper threshold value _Poff is changed. Specifically, when the first negative pressure P1 is greater than the second negative pressure P2, the negative pressure detection unit 41 increases the lower limit threshold value P _on set in the negative pressure control unit 44 by the negative pressure difference ΔP. Change to the lower threshold P _on '. On the other hand, when the first negative pressure P1 is smaller than the second negative pressure P2, the negative pressure detection unit 41 detects the temporary upper threshold value P by decreasing the upper limit threshold value P _off set in the negative pressure control unit 44 by the negative pressure difference ΔP. change to _off '. The processes of steps S5 to S8 are executed only when the negative pressure difference ΔP becomes larger than the determination threshold value P0 and the process first proceeds to "NO" in step S3.

Next, it is determined whether or not the failure identification process has been completed (S9). Specifically, it is determined whether or not the failure identification unit 43 has completed the failure identification process. If the failure identification process has not been completed (S9: NO), the first negative pressure P1 is output (S4), and the negative pressure detection process ends. Specifically, the negative pressure detection unit 41 determines that it is during the failure identification period, and outputs the first negative pressure P1 to the negative pressure control unit 44 as the negative pressure P for comparison. On the other hand, if the failure identification process is completed (S9: YES), the failure information identified by the failure identification unit 43 is output (S10), and the changed upper threshold value P _off or lower threshold value P _on is returned to the original value. returned (S11). The processes of steps S10 to S11 are executed only when the failure identification process is completed and the process first proceeds to "YES" in step S9.

Next, the correct one of the first negative pressure P1 and the second negative pressure P2 is output (S12), and the negative pressure detection process ends. Specifically, the negative pressure detection unit 41 sends, as the comparison negative pressure P, the negative pressure detected by the failure identifying unit 43 that is different from the detected negative pressure to the negative pressure control unit 44. Output.

The negative pressure detection process performed by the negative pressure detection unit 41 of the control device 4 is not limited to that shown in the above-described flowchart.

FIG. 4(a) is an example of a flowchart for explaining the failure identification processing performed by the failure identification unit 43 of the control device 4. FIG. The failure identification process is executed when the failure determination unit 42 determines that one of them has failed.

First, it is determined whether or not the negative pressure pump 3 has been driven (S21). Specifically, it is determined whether or not the negative pressure control unit 44 drives the negative pressure pump 3 . If the negative pressure pump 3 is not driven (S21: NO), the process returns to step S21 and the determination of step S21 is repeated. If the negative pressure pump 3 is driven (S21: YES), the amount of change in the negative pressure of the brake booster 9 due to the drive is estimated (S22). Specifically, the failure identification unit 43 calculates an estimated value of the amount of change in the negative pressure of the brake booster 9 based on the drive time and performance (discharge amount per unit time) of the negative pressure pump 3 . Next, the change amount ΔP1 of the first negative pressure P1 and the change amount ΔP2 of the second negative pressure P2 are measured (S23). Specifically, the failure identification unit 43 calculates the change amount ΔP1 from the first negative pressure P1 before and after the negative pressure pump 3 is driven, and calculates the change amount ΔP2 from the second negative pressure P2 before and after the drive.

Next, it is determined whether or not the amount of change ΔP1 is within the normal range (S24). Specifically, based on the amount of change estimated in step S22, the failure identification unit 43 sets a normal range in which it can be determined that the amount of change is normal. Then, the failure identification unit 43 determines whether or not the amount of change ΔP1 is within the normal range. If the amount of change ΔP1 is not within the normal range (S24: NO), it is identified that the first negative pressure P1 is abnormal, that is, the first atmospheric pressure sensor 5 is malfunctioning (S25), and the failure identification process ends. be done. If the amount of change ΔP1 is within the normal range (S24: YES), it is determined whether or not the amount of change ΔP2 is within the normal range (S26). Specifically, the failure identification unit 43 determines whether or not the amount of change ΔP2 is within the normal range. If the amount of change ΔP2 is not within the normal range (S26: NO), it is determined that the second negative pressure P2 is abnormal, that is, the second atmospheric pressure sensor 6 or the atmospheric pressure sensor 7 is out of order (S27). Specific processing is terminated. If the amount of change ΔP2 is within the normal range (S26: YES), it is determined that it could not be specified (S28), and the process returns to step S21. When the negative pressure pump 3 is driven for a short period of time, the variations ΔP1 and ΔP2 do not deviate from the normal range, and it cannot be determined which of the first negative pressure P1 and the second negative pressure P2 is abnormal. It is determined that it cannot be specified, and the operation of the next negative pressure pump 3 is awaited.

Note that the failure identification process performed by the failure identification unit 43 of the control device 4 is not limited to that shown in the flowcharts described above. In addition, the failure identification method by the failure identification unit 43 is not limited. The failure identifying unit 43 determines, for example, how the first negative pressure P1 and the second negative pressure P2 change in response to a decrease in the negative pressure of the brake booster 9 due to the operation of the brake pedal 95, and determines which one is abnormal. (Which sensor is faulty).

The negative pressure control section 44 controls driving of the negative pressure pump 3 according to the comparison negative pressure P input from the negative pressure detection section 41 . In the negative pressure control section 44, a control range of the comparative negative pressure P is set as an upper threshold value P _off and a lower threshold value P _on (<P _off ). The negative pressure control unit 44 drives the negative pressure pump 3 when the comparison negative pressure P input from the negative pressure detection unit 41 becomes equal to or lower than the lower limit threshold value P _on . As a result, the negative pressure pump 3 supplies negative pressure to the brake booster 9, so that the negative pressure of the brake booster 9 rises and the comparison negative pressure P also rises. Further, the negative pressure control unit 44 stops the negative pressure pump 3 when the comparison negative pressure P input from the negative pressure detection unit 41 is equal to or higher than the upper threshold value _Poff . As a result, the increase of the negative pressure of the brake booster 9 is stopped, and the increase of the comparison negative pressure P is also stopped. As described above, the comparison negative pressure P is controlled within the range between the upper threshold value _Poff and the lower threshold value _Pon .

In this embodiment, the negative pressure control unit 44 changes the upper limit threshold value P _off or the lower limit threshold value P _on according to instructions from the negative pressure detection unit 41 during the failure identification period. When the first negative pressure P1 is greater than the second negative pressure P2, the lower threshold P _on is changed to the provisional lower threshold P _on '. On the other hand, when the first negative pressure P1 is lower than the second negative pressure P2, the upper threshold value P _off is changed to the provisional upper threshold value P _off '.

FIG. 4B is an example of a flowchart for explaining the negative pressure control process performed by the negative pressure control section 44 of the control device 4 . The negative pressure control process is executed at regular intervals while the start switch of the vehicle 1 is on.

First, it is determined whether or not the comparative negative pressure P is equal to or lower than the lower threshold value P _on (S31). If the comparison negative pressure P is greater than the lower limit threshold value P _on (S31: NO), the process returns to step S31 and the determination of step S31 is repeated. While this determination is repeated, the negative pressure pump 3 is stopped. On the other hand, if the comparison negative pressure P is equal to or lower than the lower threshold value P _on (S31: YES), the negative pressure pump 3 is driven (S32). Specifically, the negative pressure control unit 44 turns on the negative pressure pump 3 .

Next, it is determined whether or not the comparative negative pressure P is greater than or equal to the upper threshold value _Poff (S33). If the comparison negative pressure P is smaller than the upper threshold value _Poff (S33: NO), the process returns to step S33 and the determination of step S33 is repeated. While this determination is repeated, the negative pressure pump 3 continues to be driven. On the other hand, if the comparison negative pressure P is equal to or _higher than the upper threshold value Poff (S33: YES), the negative pressure pump 3 is stopped (S34), and the negative pressure control process is terminated. Specifically, the negative pressure control unit 44 turns off the negative pressure pump 3 .

In the determination of steps S31 and S33, if there is an instruction from the negative pressure detection unit 41, the lower limit threshold value P _on or the upper limit threshold value P _off is changed. Specifically, when the first negative pressure P1 is greater than the second negative pressure P2, the lower threshold P _on is changed to the provisional lower threshold P _on ′ in step S31 during the failure identification period. Further, when the first negative pressure P1 is lower than the second negative pressure P2, the upper threshold value P _off is changed to the provisional upper threshold value P _off ' in step S33 during the failure identification period.

The negative pressure control process performed by the negative pressure control section 44 of the control device 4 is not limited to that shown in the above flowchart.

FIG. 5 is a time chart showing changes in the first negative pressure P1 and the second negative pressure P2 and the driving state of the negative pressure pump 3 when a failure occurs. FIG. 5(a) shows the case where the first negative pressure P1 is higher than the second negative pressure P2, and FIG. 5(b) shows the case where the first negative pressure P1 is lower than the second negative pressure P2. In both cases, the horizontal axis indicates the passage of time, and the vertical axis indicates the detected value of each negative pressure. In both cases, the negative pressure difference ΔP is large and equal to or greater than the determination threshold value P0, and the failure determination unit 42 determines that a failure has occurred. .

As shown in FIG. 5A, when the first negative pressure P1 is greater than the second negative pressure P2, the lower limit threshold P _on is changed to a provisional lower limit threshold P _on ′ increased by the negative pressure difference ΔP. As a result, the negative pressure control unit 44 controls the negative pressure pump when the first negative pressure P1, which is the comparative negative pressure P, becomes equal to or lower than the temporary lower limit threshold value P _on ' before reaching the lower limit threshold value P _on . 3 is driven to increase the first negative pressure P1 and the second negative pressure P2. Further, the negative pressure control unit 44 stops driving the negative pressure pump 3 when the first negative pressure P1, which is the negative pressure P for comparison, becomes equal to or higher than the upper threshold value _Poff .

Further, as shown in FIG. 5(b), when the first negative pressure P1 is smaller than the second negative pressure P2, the upper threshold value P _off is changed to a provisional upper threshold value P _off ′ reduced by the negative pressure difference ΔP. there is As a result, the negative pressure control unit 44 drives the negative pressure pump 3 when the first negative pressure P1, which is the negative pressure P for comparison, becomes equal to or lower than the lower limit threshold value P _on . The negative pressure P2 is increased. Further, the negative pressure control _{unit 44} causes the negative pressure pump 3 to drive is stopped.

As described above, the negative pressure control unit 44 drives the negative pressure pump 3 when the first negative pressure P1 or the second negative pressure P2 becomes equal to or lower than the lower limit threshold P _on . Further, the negative pressure control unit 44 stops driving the negative pressure pump 3 when the first negative pressure P1 or the second negative pressure P2 becomes equal to or higher than the upper threshold value _Poff . In both cases of FIGS. 5A and 5B, when the identification by the failure identification unit 43 is completed by driving the negative pressure pump 3, the changed upper threshold value P _off or lower threshold value P _on is used as the original value. , the negative pressure control unit 44 controls the drive of the negative pressure pump 3 based on the negative pressure identified as normal.

For example, when the driver applies the brakes suddenly, the negative pressure of the brake booster 9 drops rapidly. At this time, if one of the atmospheric pressure sensors fails, one of the first negative pressure P1 and the second negative pressure P2 becomes a value below the lower limit threshold value P _on , and if the other does not change much, the negative pressure becomes negative. The pressure difference ΔP increases, and the failure determination unit 42 determines that a failure has occurred. In this case, when the first negative pressure P1 (<the second negative pressure P2) is lower than the lower limit threshold value P _on , the negative pressure pump 3 is driven, and while the negative pressure pump 3 is being driven, the fault identifying unit 43 performs identification, and thereafter the negative pressure detection unit 41 outputs the normal negative pressure to the negative pressure control unit 44 . On the other hand, if the second negative pressure P2 (<first negative pressure P1) is lower than the lower threshold value P _on , the first negative pressure P1 becomes equal to or lower than the provisional lower threshold value P _on ', so the negative pressure pump 3 is driven. , while the negative pressure pump 3 is being driven, the fault identification unit 43 identifies the failure, and thereafter the negative pressure detection unit 41 outputs the normal negative pressure to the negative pressure control unit 44 .

Next, functions and effects of the negative pressure supply system 2 according to the first embodiment will be described.

According to the present embodiment, the negative pressure detector 41 uses the negative pressure P for comparison as the first 1 negative pressure P1 is output to the negative pressure control unit 44 . Further, the negative pressure detection unit 41 detects the first negative pressure P1 and the second negative pressure P2 as the negative pressure P for comparison after the failure identification period ends (after the failure identification unit 43 identifies the one with the failure). The more accurate one of them is output to the negative pressure control unit 44 . Therefore, the negative pressure detection unit 41 can output the comparison negative pressure P to the negative pressure control unit 44 without interruption. As a result, the negative pressure control unit 44 can control the drive of the negative pressure pump 3 without interruption even during the failure identification process.

Further, if the first negative pressure P1 is greater than the second negative pressure P2 during the failure identification period, the negative pressure detection unit 41 changes the lower limit threshold value P _on to the provisional lower limit threshold value P _{on ′} , and changes the first negative pressure P1 is lower than the second negative pressure P2, the upper threshold P _off is changed to the provisional upper threshold P _off '. Thereby, the negative pressure control unit 44 drives the negative pressure pump 3 when the first negative pressure P1 or the second negative pressure P2 becomes equal to or lower than the lower limit threshold value P _on , and the first negative pressure P1 or the second negative pressure The drive of the negative pressure pump 3 is stopped when P2 becomes equal to or greater than the upper threshold value _Poff . Therefore, even if the first negative pressure P1 is abnormal, it is possible to prevent the negative pressure pump 3 from not being driven even if the normal second negative pressure P2 falls below the lower limit threshold value P _on . Further, it is possible to prevent the negative pressure pump 3 from being stopped even when the normal second negative pressure P2 exceeds the upper threshold value _Poff . That is, the negative pressure control unit 44 can appropriately control the negative pressure pump 3 even during the failure identification period.

Further, the negative pressure control section 44 controls driving of the negative pressure pump 3 according to the comparison negative pressure P input from the negative pressure detection section 41 . The failure identification unit 43 identifies which of the negative pressure pumps 3 is malfunctioning when the negative pressure pump 3 is driven under the control of the negative pressure control unit 44 . In other words, the control device 4 does not drive the negative pressure pump 3 unnecessarily for the failure identification processing in the failure identification section 43 . As a result, it is possible to prevent the generation of operating noise due to unnecessary driving and the reduction in the life of the negative pressure pump 3 .

Further, according to this embodiment, the first atmospheric pressure sensor 5 detects the first negative pressure P1. Therefore, the negative pressure supply system 2 can detect two systems of negative pressure with three pressure sensors. Thereby, the negative pressure supply system 2 can reduce the manufacturing cost compared to the case of having four atmospheric pressure sensors (two absolute pressure sensors and two atmospheric pressure sensors). Also, the determination threshold value P0 for failure determination is set in consideration of the detection errors of the three atmospheric pressure sensors. Therefore, compared with the case where the determination threshold value P0 is set in consideration of the detection errors of the four air pressure sensors, the failure determination accuracy of the failure determination unit 42 is better.

Further, according to this embodiment, the detection signal from the first atmospheric pressure sensor 5 is input to the control device 4 via the signal line 51 . Therefore, even if the communication via the on-vehicle bus 8 fails, the control device 4 can obtain the first negative pressure P1, so that the driving of the negative pressure pump 3 can be controlled. Detection signals from the second atmospheric pressure sensor 6 and the atmospheric pressure sensor 7 are input to the control device 4 via the vehicle bus 8 . Therefore, even if the communication via the signal line 51 is not working well, the control device 4 can acquire the second negative pressure P2, so that it is possible to control the driving of the negative pressure pump 3 . The negative pressure supply system 2 can detect the correct negative pressure of the brake booster 9 and control the drive of the negative pressure pump 3 even if one of the air pressure sensors, the vehicle bus 8, and the signal line 51 fails. , the vacuum of the brake booster 9 can be adjusted. That is, the negative pressure supply system 2 is highly resistant to various failures. Further, since the detection signal from the first atmospheric pressure sensor 5 is input to the control device 4 via the signal line 51, the detection signal from the first atmospheric pressure sensor 5 is also input to the control device 4 via the vehicle bus 8. Influence on other communications via the in-vehicle bus 8 can be suppressed as compared with the case.

In this embodiment, the case where the brake booster 9 uses the negative pressure supplied from the negative pressure pump 3 has been described, but the present invention is not limited to this. The brake booster 9 may utilize the negative pressure generated by the intake air pressure of the internal combustion engine. In this case, the internal combustion engine corresponds to the "negative pressure supply source" of the present invention. Further, the brake booster 9 may use both the negative pressure supplied from the negative pressure pump 3 and the negative pressure due to the intake air pressure of the internal combustion engine.

Further, in this embodiment, the first atmospheric pressure sensor 5 outputs a detection signal to the control device 4 via the signal line 51, and the second atmospheric pressure sensor 6 and the atmospheric pressure sensor 7 output detection signals via the vehicle bus 8. Although the case of outputting to the control device 4 has been described, the present invention is not limited to this. The first atmospheric pressure sensor 5 may also output a detection signal to the control device 4 via the vehicle bus 8 . Conversely, the second atmospheric pressure sensor 6 and the atmospheric pressure sensor 7 may each output detection signals to the control device 4 via signal lines. Further, the first atmospheric pressure sensor 5 outputs a detection signal to the control device 4 via the vehicle bus 8, and the second atmospheric pressure sensor 6 and the atmospheric pressure sensor 7 output detection signals to the control device 4 via signal lines. may

Also, in the present embodiment, the case where the negative pressure detection unit 41 changes only one of the lower limit threshold value P _on and the upper limit threshold value P _off during the failure identification period has been described, but the present invention is not limited to this. The negative pressure detection unit 41 may change both the lower limit threshold value P _on and the upper limit threshold value P _off during the failure identification period.

Further, in the present embodiment, the case where the negative pressure detection unit 41 outputs the first negative pressure P1 as the comparison negative pressure P until a failure is detected and during the failure determination period has been described. It is not limited to this. The negative pressure detection unit 41 may output the second negative pressure P2 as the comparison negative pressure P, or may detect any of the average value of the first negative pressure P1 and the second negative pressure P2, the smaller one, or the larger one. may be output as the negative pressure P for comparison.

Similar to FIG. 5, FIG. 6 is a time chart showing changes in the first negative pressure P1 and the second negative pressure P2 and the driving state of the negative pressure pump 3 when a failure occurs. In FIG. 6 as well, the horizontal axis indicates the passage of time, and the vertical axis indicates the detected value of each negative pressure. Also, the negative pressure difference ΔP is large and equal to or greater than the determination threshold value P0, and the state in the failure identification period until the failure determination unit 42 determines that a failure has occurred and the failure determination unit 42 performs identification. 6 shows an example in which the negative pressure detection unit 41 outputs the average value of the first negative pressure P1 and the second negative pressure P2 as the negative pressure P for comparison. As shown in FIG. 6, the lower threshold P _on is changed to the temporary lower threshold P _on ', and the upper threshold P _off is changed to the temporary upper threshold P _off '. As a result, the negative pressure control unit 44 drives the negative pressure pump 3 when the comparative negative pressure P becomes equal to or lower than the temporary lower threshold value P _{on '} before the negative pressure P for comparison reaches the lower limit threshold value P on . The negative pressure P1 and the second negative pressure P2 are increased. In addition, the negative pressure control unit 44 stops driving the negative pressure pump 3 when the comparison negative pressure P becomes equal to or greater than the smaller provisional upper threshold value _Poff ' before reaching the upper limit threshold value _Poff . . That is, in the present modification, the negative pressure control unit 44 drives the negative pressure pump 3 before the first negative pressure P1 or the second negative pressure P2 becomes equal to or lower than the lower threshold value _Pon , and increases the negative pressure to equal to or higher than the upper threshold value _Poff . The drive of the negative pressure pump 3 is stopped before it becomes. Therefore, even if the normal one of the first negative pressure P1 and the second negative pressure P2 falls below the lower limit threshold value P _on , it is possible to prevent the negative pressure pump 3 from not being driven. Further, it is possible to prevent the negative pressure pump 3 from being stopped even if the normal one exceeds the upper limit threshold value _Poff . That is, in this modification, the negative pressure control unit 44 can appropriately control the negative pressure pump 3 even during the failure identification period.

<Second embodiment>
7 to 9 are diagrams for explaining the negative pressure supply system 2a according to the second embodiment. A schematic block diagram showing the configuration of a vehicle 1 to which a negative pressure supply system 2a according to the second embodiment is applied is the same as FIG. FIG. 7 is an example of a flowchart for explaining the negative pressure detection process performed by the negative pressure detection section 41 of the control device 4 of the negative pressure supply system 2a. FIG. 8 is an example of a flowchart for explaining the negative pressure control process performed by the negative pressure control section 44 of the control device 4 of the negative pressure supply system 2a. Similar to FIG. 5, FIG. 9 is a time chart showing changes in the first negative pressure P1 and the second negative pressure P2 and the driving state of the negative pressure pump 3 when a failure occurs.

In the negative pressure supply system 2a according to the second embodiment, the negative pressure detection unit 41 outputs the first negative pressure P1 and the second negative pressure P2 to the negative pressure control unit 44 during the failure determination period. It differs from the negative pressure supply system 2 according to the embodiment.

In this embodiment, the negative pressure detection section 41 outputs the first negative pressure P1 and the second negative pressure P2 to the negative pressure control section 44 during the failure determination period. As shown in FIG. 7, in step S9, if the failure identification process is not completed (S9: NO), the first negative pressure P1 and the second negative pressure P2 are output (S13), and the negative pressure detection process is started. finish. Specifically, the negative pressure detection unit 41 determines that it is during the failure identification period, and outputs the first negative pressure P1 and the second negative pressure P2 to the negative pressure control unit 44 . The flowchart shown in FIG. 7 is the same as the flowchart shown in FIG. 3 in other parts.

Further, in the present embodiment, the negative pressure controller 44 receives the first negative pressure P1 and the second negative pressure P2 from the negative pressure detector 41 during the failure identification period. Note that, in the present embodiment, the upper threshold value P _off and the lower threshold value P _on are not changed. The negative pressure control unit 44 compares the smaller one of the first negative pressure P1 and the second negative pressure P2 with the lower limit threshold P _on and sets the larger one of the first negative pressure P1 and the second negative pressure P2 to the upper limit. Compare with threshold _Poff . As shown in FIG. 8, in the flowchart of the negative pressure control process, in contrast to the flowchart shown in FIG. It is changed to step S35 in which it is compared with _on . Further, step S33 is changed to step S36 in which the larger one of the first negative pressure P1 and the second negative pressure P2 is compared with the upper limit threshold value _Poff . Other parts of the flowchart shown in FIG. 8 are similar to the flowchart shown in FIG. 4(b). While only the first negative pressure P1 is input from the negative pressure detection unit 41 as the comparison negative pressure P, the negative pressure control unit 44, in steps S35 and S36, sets the first negative pressure P1 to the lower limit threshold value P _on or It is compared with an upper threshold _Poff .

Similar to FIG. 5, FIG. 9 shows changes in the first negative pressure P1 and the second negative pressure P2 and the driving state of the negative pressure pump 3 when a failure occurs. In FIG. 9 as well, the horizontal axis indicates the passage of time, and the vertical axis indicates the detected value of each negative pressure. Also, the negative pressure difference ΔP is large and equal to or greater than the determination threshold value P0, and the state in the failure identification period until the failure determination unit 42 determines that a failure has occurred and the failure determination unit 42 performs identification. Also, FIG. 9 shows an example in which the first negative pressure P1 is lower than the second negative pressure P2. As shown in FIG. 9, the negative pressure control unit 44 drives the negative pressure pump 3 when the first negative pressure P1 (<the second negative pressure P2) becomes equal to or lower than the lower threshold value P _on . The pressure P1 and the second negative pressure P2 are increased. Further, the negative pressure control unit 44 stops driving the negative pressure pump 3 when the second negative pressure P2 (>the first negative pressure P1) becomes equal to or higher than the upper threshold value _Poff .

Also in this embodiment, the negative pressure detection unit 41 can continuously output the comparison negative pressure P or the first negative pressure P1 and the second negative pressure P2 to the negative pressure control unit 44 . As a result, the negative pressure control unit 44 can control the drive of the negative pressure pump 3 without interruption even during the failure identification process. Further, the negative pressure detection unit 41 outputs the first negative pressure P1 and the second negative pressure P2 to the negative pressure control unit 44 during the failure identification period. Then, the negative pressure control unit 44 drives the negative pressure pump 3 when the smaller one of the first negative pressure P1 and the second negative pressure P2 becomes equal to or lower than the lower limit threshold value P _on . The driving of the negative pressure pump 3 is stopped when the larger one of the two negative pressures P2 becomes equal to or higher than the upper threshold value _Poff . Therefore, the negative pressure control unit 44 can appropriately control the negative pressure pump 3 even during the failure identification period. Further, the control device 4 does not drive the negative pressure pump 3 unnecessarily for the failure identification processing in the failure identification section 43 . As a result, it is possible to prevent the generation of operating noise due to unnecessary driving and the reduction in the life of the negative pressure pump 3 .

<Third Embodiment>
FIG. 10 is a schematic block diagram showing the configuration of the vehicle 1 to which the negative pressure supply system 2b according to the third embodiment is applied. In FIG. 10, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as in the above embodiment. A negative pressure supply system 2b according to the third embodiment differs from the negative pressure supply system 2 according to the first embodiment in the method of detecting the first negative pressure P1.

In this embodiment, the negative pressure supply system 2b includes a first atmospheric pressure sensor 5a and an atmospheric pressure sensor 7a instead of the first atmospheric pressure sensor 5. As shown in FIG. Like the second atmospheric pressure sensor 6, the first atmospheric pressure sensor 5a is a so-called absolute pressure sensor, and is attached to the negative pressure chamber 91 of the brake booster 9. The atmospheric pressure ( absolute pressure). The first atmospheric pressure sensor 5 a outputs a detection signal corresponding to the absolute pressure inside the negative pressure chamber 91 . The detection signal is input to the control device 4 via the vehicle bus 8 . The atmospheric pressure sensor 7a, like the atmospheric pressure sensor 7, is a so-called absolute pressure sensor, is arranged outside the brake booster 9, and detects the atmospheric pressure. The mounting position of the atmospheric pressure sensor 7a is not limited. The atmospheric pressure sensor 7a outputs a detection signal corresponding to the atmospheric pressure. The detection signal is input to the control device 4 via the vehicle bus 8 . That is, the negative pressure supply system 2b includes two absolute pressure sensors, a first atmospheric pressure sensor 5a and a second atmospheric pressure sensor 6, and two atmospheric pressure sensors 7 and 7a.

Further, in the present embodiment, the negative pressure detection unit 41 acquires the atmospheric pressure (absolute pressure) in the negative pressure chamber 91 based on the detection signal input from the first atmospheric pressure sensor 5a, and inputs it from the atmospheric pressure sensor 7a. Atmospheric pressure is obtained based on the detected signal. Then, the negative pressure detection unit 41 calculates the first negative pressure P1 by subtracting the air pressure (absolute pressure) inside the negative pressure chamber 91 from the atmospheric pressure. In this embodiment, the combination of the first atmospheric pressure sensor 5a, the atmospheric pressure sensor 7a, and the negative pressure detection section 41 corresponds to the "first negative pressure detection section" of the present invention.

Also in the present embodiment, the negative pressure detection unit 41 can continuously output the comparison negative pressure P to the negative pressure control unit 44 . As a result, the negative pressure control unit 44 can control the drive of the negative pressure pump 3 without interruption even during the failure identification process. Further, if the first negative pressure P1 is greater than the second negative pressure P2 during the failure identification period, the negative pressure detection unit 41 changes the lower limit threshold value P _on to the provisional lower limit threshold value P _{on ′} , and changes the first negative pressure P1 is lower than the second negative pressure P2, the upper threshold P _off is changed to the provisional upper threshold P _off '. Thereby, the negative pressure control unit 44 drives the negative pressure pump 3 when the first negative pressure P1 or the second negative pressure P2 becomes equal to or lower than the lower limit threshold value P _on , and the first negative pressure P1 or the second negative pressure The drive of the negative pressure pump 3 is stopped when P2 becomes equal to or greater than the upper threshold value _Poff . Therefore, the negative pressure control unit 44 can appropriately control the negative pressure pump 3 even during the failure identification period. Further, the control device 4 does not drive the negative pressure pump 3 unnecessarily for the failure identification processing in the failure identification section 43 . As a result, it is possible to prevent the generation of operating noise due to unnecessary driving and the reduction in the life of the negative pressure pump 3 . Further, according to the present embodiment, the signal line 51 connecting the first atmospheric pressure sensor 5 and the control device 4 in the first embodiment is not required, so the manufacturing cost can be suppressed.

The negative pressure supply system according to the present invention is not limited to the embodiments described above. The specific configuration of each part of the negative pressure supply system according to the present invention can be changed in various ways.

1: Vehicles 2, 2a, 2b: Negative pressure supply system 3: Negative pressure pump 31: Piping 4: Control device 41: Negative pressure detection unit 42: Failure determination unit 43: Failure identification unit 44: Negative pressure control units 5, 5a : First atmospheric pressure sensor 51 : Signal line 6 : Second atmospheric pressure sensors 7, 7a: Atmospheric pressure sensor 8 : Vehicle bus 9 : Brake booster 91 : Negative pressure chamber 95 : Brake pedal

Claims (1)

A negative pressure supply system for supplying negative pressure to a negative pressure chamber of a brake booster,
a negative pressure source;
a controller for controlling the negative pressure supply;
a first negative pressure detection unit and a second negative pressure detection unit that respectively detect negative pressure in the negative pressure chamber;
with
The control device is
a first negative pressure detected by the first negative pressure detecting section , a second negative pressure detected by the second negative pressure detecting section , the smaller one of the first negative pressure and the second negative pressure, the first negative pressure and the second negative pressure, or the average value of the first negative pressure and the second negative pressure. a negative pressure control unit that drives a supply source and stops the negative pressure supply source when the comparison negative pressure is equal to or higher than an upper threshold;
a failure determination unit that determines occurrence of a failure in either the first negative pressure detection unit or the second negative pressure detection unit based on the first negative pressure and the second negative pressure;
with
The negative pressure control unit sets the lower limit threshold to the first negative pressure and the second negative pressure during a failure identification period from when the failure determination unit determines that a failure has occurred until it identifies which one has failed. The temporary lower threshold value is increased based on the difference from the negative pressure, or the upper threshold value is changed to the temporary upper threshold value that is decreased based on the difference between the first negative pressure and the second negative pressure. a negative pressure supply system for performing comparison with the comparative negative pressure .

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