JP2018122655A - Brake system - Google Patents

Abstract

SOLUTION: A vacuum hose 42 branches from an air intake pipe 30 constituting an engine 10, and a brake booster 48 amplifies tread force of a brake pedal 50 by utilizing negative pressure to be supplied through the vacuum hose 42. A VSC actuator 54 adjusts braking force based on the tread force amplified by the brake booster 48. A negative pressure adjustment valve 46 is provided in the vacuum hose 42 and supplies at least part of intake manifold negative pressure to the brake booster 48. An ECU 58, when the VSC actuator 54 is normal, controls settings of the negative pressure adjustment valve 46 so that booster negative pressure falls within a range where a minimum value of the intake manifold negative pressure is set as an upper limit value.EFFECT: This can stabilize braking force.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a brake system, and in particular, a hose that branches from an intake pipe that constitutes an engine, a brake booster that amplifies the depressing force of a brake pedal using negative pressure supplied through the hose, and is amplified by a brake booster The present invention relates to a brake system including an actuator that adjusts a braking force based on a pedaling force that is applied.

  An example of this type of brake system is disclosed in Patent Document 1. According to this document, a vehicular brake system is mounted on a vehicle having an operation mode in which an engine is stopped when the vehicle is stopped, and generates a hydraulic pressure corresponding to a brake operation, and a hydraulic pressure from the master cylinder. In addition to the brake actuator that transmits to the wheel cylinder of each wheel, a pressurizing pump that pressurizes the hydraulic pressure of the brake actuator when the vehicle is stopped is provided.

  As a result, when the vehicle is stopped and the negative pressure of the brake booster is insufficient due to the depressing of the brake pedal, the braking force by the pressurizing pump is applied to each wheel of the vehicle in addition to the braking force by the depression force. As a result, the braking force of the vehicle can be appropriately ensured when the vehicle is stopped and the engine is stopped.

JP 2010-137828 A

  However, the negative pressure supplied to the brake booster changes every time the engine is repeatedly operated / stopped, and it is difficult to properly control the pressure applied by the pressurization pump and hence the braking force.

  Therefore, a main object of the present invention is to provide a brake system capable of stabilizing the braking force.

  The brake system of the present invention includes a hose that branches from an intake pipe that constitutes an engine, a brake booster that amplifies the pedal effort of the brake pedal using negative pressure supplied through the hose, and a pedaling force that is amplified by the brake booster. A brake system comprising an actuator for adjusting a braking force based on a valve provided on a hose and supplying at least a part of the negative pressure generated in the engine to the brake booster, and supplied to the brake booster when the actuator is normal And a control means for controlling the setting of the valve so that the negative pressure falls within a range in which the minimum value of the negative pressure generated in the engine is an upper limit.

  At least a part of the negative pressure generated in the engine is supplied to the brake booster via a hose provided with a valve. When the actuator is normal, the valve setting is controlled so that the negative pressure supplied to the brake booster falls within a range where the minimum value of the negative pressure generated in the engine is an upper limit. As a result, the braking force can be stabilized.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

It is a block diagram which shows a part of principal part structure of the vehicle of this Example. It is a graph which shows an example of the time change of the negative pressure which occurs in an engine. It is a flowchart which shows an example of operation | movement of ECU. (A) is a graph which shows an example of the relationship between the brake pedal force and the braking force when the VSC actuator is normal, and (B) is an example of the relationship between the brake pedal force and the braking force when the VSC actuator is defective. It is a graph which shows. It is a flowchart which shows another example of operation | movement of ECU. (A) is a graph which shows another example of the relationship between brake pedal force and braking force when the VSC actuator is normal, and (B) is the relationship between brake pedal force and braking force when the VSC actuator is defective. It is a graph which shows another example of.

  Referring to FIG. 1, the vehicle of this embodiment includes an engine 10 as a power source. An intake pipe 30 is connected to the combustion chamber 14 provided in the cylinder 12 via an intake valve 16, and an exhaust pipe 32 is connected via an exhaust valve 18. 1, only a single cylinder 12 is shown, but the engine 10 has a plurality of cylinders 12, 12,. The intake pipe 30 branches to each cylinder 12 at a position upstream of the intake valve 16.

  The intake pipe 30 includes a single throttle valve 34 whose opening degree is adjusted by a valve motor (not shown), and a fuel injection device 36 assigned to each cylinder 12 to inject fuel into the intake pipe 30. Provided. A surge tank 38 for leveling the air flow rate is provided at a position downstream of the throttle valve 34 and upstream of the fuel injection device 36 (a branch position of the intake pipe 30).

  When the engine 10 is in an idle state, the opening of the throttle valve 34 is adjusted to an opening that can maintain the idle state. The intake air amount and the fuel injection amount of the fuel injection device 36 are defined by the opening of the throttle valve 34. When an accelerator pedal (not shown) is depressed from this state, the throttle valve 34 is opened. As a result, the intake air amount and the fuel injection amount of the fuel injection device 36 are increased.

  The air-fuel mixture obtained by mixing the fuel with the intake air is supplied to the combustion chamber 14 when the intake valve 16 is opened. The supplied air-fuel mixture is ignited by the spark plug 22 immediately before the piston 20 connected to the crankshaft 26 via the connecting rod 24 reaches the top dead center. The piston 20 moves up and down by the explosion of the air-fuel mixture, whereby the crankshaft 26 rotates. Further, the air after combustion of the air-fuel mixture, that is, the exhaust gas, is discharged to the exhaust pipe 32 when the exhaust valve 18 is opened.

  A flywheel 28 is attached to the crankshaft 26, and fluctuations in the rotational speed of the crankshaft 26, that is, the rotational speed of the engine 10 are suppressed by the flywheel 28. The rotational force of the crankshaft 26 is transmitted to a drive shaft (not shown), whereby the vehicle moves forward or backward.

  The vehicle of this embodiment also includes a brake system 40 including a brake pedal 50 provided in the driver's seat. When the brake pedal 50 is depressed, the brake pedal force is amplified by the brake booster 48 and transmitted to the master cylinder 52.

  The negative pressure chamber of the brake booster 48 is connected to the intake pipe 30 by a vacuum hose 42. In addition to the check valve 44, the vacuum hose 42 is provided with a negative pressure adjustment valve 46. The negative pressure generated on the intake pipe 30 side of the negative pressure adjusting valve 46 is defined as “intake negative pressure”, and the negative pressure generated on the brake booster 48 side of the negative pressure adjusting valve 46 is defined as “booster negative pressure”. Then, at least a part of the intake manifold negative pressure becomes a booster negative pressure, and the value of the booster negative pressure is adjusted by the negative pressure adjusting valve 46.

  The brake booster 48 amplifies the depression force of the brake pedal 50 using the booster negative pressure generated in this way. The master cylinder 52 supplies a hydraulic pressure (hydraulic pressure) corresponding to the amplified pedaling force to the VSC actuator 54, and the VSC actuator 54 pressurizes, reduces, or holds the supplied hydraulic pressure. The brake pads 56f1, 56f2, 56r1, and 56r2 provided on the four wheels, respectively, exhibit a braking force based on the hydraulic pressure thus adjusted.

  The intake manifold negative pressure changes every moment as shown in FIG. 2 according to the operating state of the engine 10 (for example, the opening degree of the throttle valve 34). According to FIG. 2, the intake manifold negative pressure dynamically changes within a range where “PR0” is the lowest value. A specific value of “PR0” is derived from an empirical rule, and “PR1” representing the intake manifold negative pressure dynamically changes within a range of “PR0” or more.

  Based on this, the ECU 58 repeatedly executes the valve control process according to the flowchart shown in FIG. The control program corresponding to this flowchart is stored in the memory 58m.

  First, in step S1, the state of the VSC actuator 54 is detected. In step S3, it is determined whether or not the VSC actuator 54 is normal based on the detection result in step S1. If a determination result is YES, it will progress to step S5 and will control the setting of the negative pressure adjustment valve 46 so that a booster negative pressure may show "0". Note that “0” noted here is positioned as one value within a range having “PR0” as an upper limit.

  On the other hand, if the determination result in step S3 is NO, the setting of the negative pressure adjusting valve 46 is controlled so that the booster negative pressure matches the intake manifold negative pressure (= PR1). The current valve control process ends after the process of step S5 or S7.

  Therefore, if the VSC actuator 54 is normal, the braking force is generated as shown in FIG. If the VSC actuator 54 is defective, the braking force is generated as shown in FIG. 4A and 4B, the shaded area represents the braking force corresponding to the brake pedal force, the hatched area represents the braking force assisted by the VSC actuator 54, and the dot area is represented by the brake booster 48. It represents the assisted braking force.

  That is, when the VSC actuator 54 is normal, the braking force is assisted by the VSC actuator 54, and when the VSC actuator 54 is defective, the braking force is assisted by the brake booster 48.

  As can be seen from the above description, the vacuum hose 42 branches off from the intake pipe 30 constituting the engine 10, and the brake booster 48 uses the negative pressure supplied via the vacuum hose 42 to depress the pedal force of the brake pedal 50. Amplify. The VSC actuator 54 adjusts the braking force based on the pedaling force amplified by the brake booster 48.

  Based on this, the negative pressure adjusting valve 46 is provided in the vacuum hose 42 and supplies at least part of the intake manifold negative pressure to the brake booster 48. Further, the ECU 58 controls the negative pressure adjusting valve so that when the VSC actuator 54 is normal, the booster negative pressure indicates “0” (= a value that falls within the range having the minimum value “PR0” of the intake manifold negative pressure as an upper limit). 46 is controlled (S5).

  As a result, the braking system 40 including the assist of the VSC actuator 54 is stabilized, the brake feeling does not change, and the brake system 40 that does not feel uncomfortable is realized. Further, when the booster negative pressure is “0”, the brake feeling is completely matched and the configuration is simplified.

  Furthermore, when a defect occurs in the VSC actuator 54, the booster negative pressure is adjusted to the intake manifold negative pressure (S7), so that the braking force can be ensured although it is lower than the normal braking force.

  In this embodiment, the booster negative pressure is set to “0” when the VSC actuator 54 is normal. However, instead of this, the booster negative pressure may be set to “PR0”. In this case, as shown in FIG. 5, step S5 ′ is executed instead of step S5. In step S5 ′, the setting of the negative pressure adjusting valve 46 is controlled so that the booster negative pressure indicates “PR0”.

  Therefore, if the VSC actuator 54 is normal, the braking force is generated as shown in FIG. On the other hand, if there is a defect in the VSC actuator 54, the braking force is generated as shown in FIG. When the booster negative pressure is set to “PR0” in this way, the load on the VSC actuator 54 at normal time is reduced, and the durability of the VSC actuator 54 is improved.

DESCRIPTION OF SYMBOLS 10 ... Engine 30 ... Intake pipe 40 ... Brake system 42 ... Vacuum hose 46 ... Negative pressure adjustment valve 48 ... Brake booster 50 ... Brake pedal 54 ... VSC actuator 58 ... ECU

Claims (1)

A hose branching from the intake pipe constituting the engine,
A brake system comprising: a brake booster that amplifies the depressing force of a brake pedal using negative pressure supplied through the hose; and an actuator that adjusts a braking force based on the depressing force amplified by the brake booster,
A valve provided on the hose for supplying at least a part of the negative pressure generated in the engine to the brake booster; and a negative pressure supplied to the brake booster when the actuator is normal A brake system further comprising control means for controlling the setting of the valve so as to fall within a range having a minimum value of pressure as an upper limit.

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