JP2012193625A - Brake control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device for vehicle capable of improving fuel consumption by increasing a frequency or a time capable of stopping an engine by raising an intake pipe negative pressure supplied to a brake booster before stopping the engine.SOLUTION: In the brake control device (control unit 20) for a vehicle having the brake booster 5 for assisting the brake depression force of a driver using the intake pipe negative pressure of the engine 10, carrying out an idle up for an air conditioner for increasing an intake air quantity during driving the air conditioner and controlling and stopping the engine 10 when a predetermined condition is satisfied during deceleration travelling, the first vehicle speed for stopping the engine 10 during deceleration and the second speed for inhibiting the idle stop for the air conditioner at a high speed side more than the first vehicle speed are set, and the idle stop for the air conditioner is completed before stopping the engine 10.

Description

  The present invention relates to a brake control device for a vehicle that controls to stop an engine when a predetermined condition is satisfied during deceleration traveling.

  In order to improve fuel efficiency, reduce CO2 emissions, reduce noise, etc., the engine is stopped when predetermined conditions are satisfied while driving at a reduced speed, and the driver's brakes are made using the intake pipe negative pressure. In a vehicle equipped with a brake booster that assists the pedal effort, after the engine is stopped, the intake pipe negative pressure cannot be supplied to the brake booster, and the brake assist force cannot be generated.

  Here, FIG. 5 shows the time change of the vehicle speed and the negative pressure (the intake pipe negative pressure supplied to the brake booster). When the brake operation is performed at the time t1 shown in the figure, the vehicle speed linearly increases with time. In addition, the negative pressure is reduced from P1 to P2 because the negative pressure is consumed in the brake booster. The engine is stopped when the vehicle speed drops to V1 (for example, 10 km / h) at time t2, and thereafter no negative pressure is generated until the vehicle stops (vehicle speed = 0) (time t2 to t3). . In this way, when the engine stops, intake pipe negative pressure does not occur, and the negative pressure supplied to the brake booster is insufficient. Therefore, when negative pressure is consumed in the brake booster, it is necessary to restart the engine and stop the engine. It is not possible to enjoy benefits such as improved fuel economy.

  Therefore, hybrid vehicles and idling stop vehicles are equipped with a negative pressure supply source other than the intake pipe, such as an electric negative pressure pump, or when the intake pipe negative pressure supplied to the brake booster is insufficient, the engine is controlled not to stop. Things have been done.

  By the way, in order to ensure that the engine rotation can be stably obtained even when the air conditioner is loaded, an air conditioner idling-up vehicle that increases the intake air amount of the engine while the air conditioner is being driven. Since the intake pipe negative pressure decreases when the engine idle up is executed, there is a problem that the negative pressure supplied to the brake booster is insufficient.

  In Patent Document 1, in a vehicle brake device in which an idle up device is provided in parallel with an intake pipe of an engine, a switch linked to a brake pedal is provided, and when a brake operation is detected by the switch, the idle up device is turned off. Therefore, a configuration is proposed in which a decrease in the negative pressure supplied to the brake booster is prevented.

JP-A-7-069205

  However, the configuration proposed in Patent Document 1 is not applied to a brake device for a vehicle that stops the engine when a predetermined condition is satisfied during deceleration traveling, and negative pressure is generated after the engine stops. It is impossible to compensate for the lack of negative pressure due to failure.

  The present invention has been made in view of the above problems, and the purpose of the invention is to increase the frequency and time at which the engine can be stopped by increasing the intake pipe negative pressure supplied to the brake booster before the engine is stopped. An object of the present invention is to provide a vehicle brake control device capable of improving fuel consumption.

  In order to achieve the above object, an invention according to claim 1 includes a brake booster for assisting a driver's brake pedal force by utilizing negative pressure of an intake pipe of an engine, and for an air conditioner that increases an intake air amount during driving of the air conditioner. In a vehicle brake control device for performing idle-up and stopping the engine when a predetermined condition is satisfied during deceleration traveling, a first vehicle speed for stopping the engine during deceleration and a higher speed than the first vehicle speed A second vehicle speed for prohibiting the air-conditioner idle up is set so that the air-conditioner idle up ends before the engine stops.

  The invention according to claim 2 is characterized in that, in the invention according to claim 1, the idle-up for the air conditioner is terminated before the engine is stopped and the engine component is controlled so that the intake pipe negative pressure is increased.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a negative pressure sensor that detects the intake pipe negative pressure is provided, and the intake pipe negative pressure detected by the negative pressure sensor is equal to or greater than a set value. In some cases, the air conditioning idle up is not terminated before the engine is stopped.

  According to the first aspect of the present invention, the intake pipe negative pressure is increased by completing the idle-up for the air conditioner before the engine is stopped so that the intake pipe negative pressure is not generated. Therefore, the intake pipe negative pressure supplied to the brake booster is increased. Frequency at which the engine can be stopped without causing problems such as restarting the engine after the engine has stopped due to insufficient pressure, or stopping the engine even if the vehicle speed is reduced to the first vehicle speed. You can improve fuel economy by increasing time and time.

  According to the second aspect of the present invention, in addition to the increase in the intake pipe negative pressure by ending the idle-up for the air conditioner before the engine is stopped, the engine parts are controlled (for example, the throttle valve is fully closed, the transmission is Since the intake pipe negative pressure is increased by connecting the lockup clutch of the engine and forcibly rotating the engine (the engine brake state is set)), the intake pipe negative pressure supplied to the brake booster is further increased.

  According to the third aspect of the present invention, when the intake pipe negative pressure detected by the negative pressure sensor is equal to or higher than the set value, the intake pipe supplied to the brake booster without ending the air conditioner idle up before the engine is stopped. There is no shortage of negative pressure, and the air conditioner can be continuously driven as it is, so that the comfort of the passenger compartment by the air conditioner is not impaired.

It is a system configuration figure of the brake control device concerning the present invention. It is a figure which shows the time change of the vehicle speed and negative pressure (intake pipe negative pressure) of a vehicle provided with the brake control apparatus which concerns on this invention. It is a flowchart which shows the control procedure of the brake control apparatus which concerns on this invention. It is a flowchart which shows another embodiment of the control procedure of the brake control apparatus which concerns on this invention. It is a figure which shows the time change of the vehicle speed and negative pressure (intake pipe negative pressure) of a vehicle provided with the conventional brake control apparatus.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a system configuration diagram of a vehicle brake control device according to the present invention. The vehicle according to the present embodiment is a vehicle that controls engine 10 to stop when a predetermined condition is satisfied during deceleration traveling. The braking system is configured as shown in FIG.

  That is, the brake device 1 is provided with a brake arm 3 that swings in the vehicle front-rear direction around the pedal shaft 2 at the upper end, and a driver steps on the lower end of the brake arm 3 with his / her foot. A brake pedal 4 is attached. The brake arm 3 is connected to the master cylinder 6 via a brake booster 5 for reducing the driver's stepping force during the brake operation. The master cylinder 6 determines the amount of depression of the brake pedal 4 by the driver. Appropriate brake fluid pressure is generated. The brake pressure generated in the master cylinder 6 is supplied to a wheel cylinder of a disc brake (not shown) provided on each wheel via a brake pipe 7, whereby each disc brake is operated to brake the rotation of each wheel. As a result, the traveling vehicle is decelerated or stopped.

  On the other hand, the intake pipe 11 of the engine 10 is provided with a throttle valve 12 and an idle-up device 13 that are opened and closed in conjunction with an accelerator pedal (not shown). The negative pressure chamber is connected by a vacuum pipe 14, and a check valve 15 is provided in the middle of the vacuum pipe 14.

  Incidentally, an air conditioner (not shown) that is driven by a part of the power of the engine 10 is mounted on the vehicle. When this air conditioner is used, the load on the engine 10 that drives the compressor of the air conditioner suddenly increases, so that the normal idling speed cannot be maintained. For this reason, when the air conditioner is used, the idle up device 13 increases the intake air amount passing through the intake pipe 11 and increases the engine rotational speed (idle up) to maintain a predetermined idle rotational speed. . The idle up device 13 includes an auxiliary air passage 16 provided in the intake pipe 11 by bypassing the throttle valve 12, and an idle control valve 17 provided in the auxiliary air passage 16. The control unit (ECU) 20 controls the opening and closing thereof.

  The control unit 20 constitutes a brake control device according to the present invention, which includes a throttle opening sensor 21 that detects the opening (engine load) of the throttle valve 12, and a vehicle speed sensor that detects the vehicle speed. 22, a negative pressure sensor 23 for detecting an intake pipe negative pressure generated downstream of the throttle valve 12 of the intake pipe 11, an air conditioner switch 24 for detecting the use state of an air conditioner (not shown), and driving of the compressor of the air conditioner are connected (ON) / OFF) The air conditioner relay 25 is electrically connected.

  Thus, when the air conditioner is used while the vehicle is running, the load on the engine 10 increases and the engine speed decreases, so that the control unit 20 is connected to the idle-up device 13 to compensate for the decrease in engine speed. The idle control valve 17 is opened to an opening corresponding to the engine load (this operation is referred to as “air conditioner idle up”). Then, part of the air flowing through the intake pipe 11 bypasses the throttle valve 12 and flows through the auxiliary air passage 16, so that the amount of air introduced into the engine 10 (intake amount) is increased by that amount, thereby causing engine rotation. The decrease in the number is compensated, and the engine 10 rotates at a predetermined rotational speed.

  By the way, since the engine 10 is operating, the engine 10 takes in air, and a negative pressure (intake pipe negative pressure) is generated in the intake pipe 11 (a portion of the intake pipe 11 downstream of the throttle valve 12). The negative pressure is supplied from the vacuum pipe 14 to the negative pressure chamber of the brake booster 5 by opening the check valve 15, and when the driver performs a brake operation to depress the brake pedal 4, the pedal pressure is boosted by the brake booster 5. Therefore, the physical burden on the driver is reduced.

  Here, since the air conditioner is used as described above, if the amount of air flowing downstream of the throttle valve 12 of the intake pipe 11 is increased by the idle-up device 13, it is generated downstream of the throttle valve 12 of the intake pipe 11. Negative pressure decreases. That is, when the air conditioner idle up is executed because the air conditioner is used, the negative pressure supplied to the brake booster 5 decreases.

  Thereafter, when the air conditioner relay 25 is turned off because the use of the air conditioner is stopped, it is not necessary to drive the compressor of the air conditioner and the load on the engine is reduced, so that it is not necessary to perform idle up for the air conditioner. For this reason, the control unit 20 turns off the air conditioner switch 14 to stop the driving of the compressor of the air conditioner and fully closes the idle control valve 17 to stop the idle up for the air conditioner. As a result, the flow rate of air flowing downstream of the throttle valve 12 of the intake pipe 11 decreases, so that the negative pressure generated downstream of the throttle valve 12 of the intake pipe 11 increases, and a high negative pressure is supplied to the brake booster 5.

  Thus, the control unit 20 constituting the brake control device according to the present invention prohibits the first vehicle speed V1 for stopping the engine 10 when the vehicle is decelerated and idle-up for the air conditioner on the higher speed side than the first vehicle speed V1. The second vehicle speed V2 to be set is set so that the idle-up for the air conditioner is finished before the engine 10 is stopped. Here, the control procedure by the control unit 20 will be described below with reference to FIGS.

  FIG. 2 is a diagram showing temporal changes in vehicle speed and negative pressure (intake pipe negative pressure) during deceleration of the vehicle, and FIG. 3 is a flowchart showing a control procedure by the control unit 20. When the vehicle is running at a vehicle speed V as shown in FIG. 2 while using the air conditioner, when the driver starts a brake operation at time t1, the negative pressure is consumed because the negative pressure is consumed in the brake booster 5. The vehicle gradually decreases linearly with time as it decreases from P1 to P2. Thereafter, the control unit 20 determines whether or not the vehicle speed has decreased to the second vehicle speed V2 (step S1 in FIG. 3), and when the vehicle speed decreases to the second vehicle speed V2 at time t2 shown in FIG. 2 (in step S1). When the determination result is Yes, the air-conditioner idle-up is terminated (step S2). Then, as shown in FIG. 2, the negative pressure downstream of the throttle valve 12 of the intake pipe 11 is increased to P3 (step S3). In addition, when the determination result in step S1 is No, the determination in step S2 is repeated (step S7).

  Next, the control unit 20 determines whether or not the vehicle speed has decreased to the first vehicle speed V1 (whether or not the engine stop condition has been satisfied) (step S4). As shown in FIG. When the vehicle speed decreases to the first vehicle speed V1 (when the determination at Step S4 or the result is Yes), the engine 10 is stopped (Step S5), and the process ends (Step S6). When the engine 10 is stopped at time t3 as described above, no negative pressure is generated in the intake pipe 11 until time t4 (time t3 to t4) after which the vehicle stops (V = 0). If the determination result in step S4 is No, the determination in step S4 is repeated until the vehicle speed decreases to the first vehicle speed V1 (step S7).

  As described above, in the present embodiment, the intake pipe negative pressure is increased by terminating the air conditioner idle-up before the stop of the engine 10 at which the intake pipe negative pressure is not generated. Since the intake pipe negative pressure is insufficient, the engine 10 may be restarted after the engine 10 is stopped, or the engine 10 may not be stopped even if the vehicle speed is reduced to the first vehicle speed V1. In addition, the frequency and time at which the engine 10 can be stopped can be increased to improve fuel efficiency.

  In addition, the air-conditioner idle-up is terminated before the engine 10 is stopped, and the intake pipe negative pressure is increased, for example, the throttle valve 12 is fully closed, or a lockup clutch of a transmission (not shown) is connected. If the engine 10 is forcibly rotated (engine brake state is set), the intake pipe negative pressure can be further increased before the engine 10 is stopped, and the above-described effect can be obtained more reliably.

  In the above embodiment, when the vehicle speed drops to the second vehicle speed V2, the idle-up for the air conditioner is uniformly terminated. However, the negative pressure sensor 23 is sufficient because the intake pipe negative pressure at that time is sufficient. When the detected intake pipe negative pressure (negative pressure downstream of the throttle valve 12 in the intake pipe 11) is equal to or higher than a set value, the air-conditioner idle up may not be terminated before the engine 10 is stopped. The control flow is shown in FIG.

  That is, FIG. 4 is a flowchart showing another embodiment of the control procedure by the control unit 20, and in this embodiment, when the vehicle speed decreases to the second vehicle speed V2 (when the determination result in step S11 is Yes) It is determined whether or not the intake pipe negative pressure detected by the negative pressure sensor 23 is equal to or lower than a set value (a state where the negative pressure is insufficient) (step S12). If the determination result in step S12 is No, the process proceeds to step S15 without ending the air conditioner idle up.

  On the other hand, when the intake pipe negative pressure detected by the negative pressure sensor 23 is equal to or lower than the set value (a state where the negative pressure is insufficient) (when the determination result in Step S12 is Yes), the same as in the above embodiment. (Steps S13 to S18) are executed.

  In this way, when the intake pipe negative pressure detected by the negative pressure sensor 23 is equal to or higher than the set value, the intake pipe negative pressure supplied to the brake booster 5 without ending the air-conditioner idle up before the engine 10 is stopped. Therefore, the air conditioner can be continuously driven as it is. For this reason, the comfort of the vehicle interior by an air conditioner is not impaired.

DESCRIPTION OF SYMBOLS 1 Brake device 4 Brake pedal 5 Brake booster 10 Engine 11 Intake pipe 12 Throttle valve 13 Idle up device 14 Vacuum piping 16 Auxiliary air passage 17 Idle control valve 20 Control unit (brake control device)
22 Vehicle speed sensor 23 Negative pressure sensor 24 Air conditioner switch 25 Air conditioner relay V1 1st vehicle speed V2 2nd vehicle speed

Claims (3)

A brake booster that assists the driver's brake pedal force by using the negative pressure of the intake pipe of the engine is used to perform idle-up for the air conditioner to increase the amount of intake air while the air conditioner is operating and to satisfy certain conditions during deceleration When the vehicle brake control device controls the engine to stop,
A first vehicle speed for stopping the engine when decelerating and a second vehicle speed for prohibiting the air-conditioner idle-up on a higher speed side than the first vehicle speed are set so that the air-conditioner idle-up ends before the engine stops. A brake control device for a vehicle.   2. The vehicle brake control device according to claim 1, wherein the engine component is controlled so that the intake pipe negative pressure is increased while the air-conditioner idle-up is ended before the engine is stopped. A negative pressure sensor for detecting the intake pipe negative pressure is provided, and when the intake pipe negative pressure detected by the negative pressure sensor is equal to or higher than a set value, the air conditioner idle up is not terminated before the engine is stopped. The brake control device for a vehicle according to claim 1 or 2.

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