JP5579103B2 - Control device for idle stop car - Google Patents

Description

  The present invention relates to an idle stop vehicle that restarts an engine by satisfying an engine restart condition that includes at least one of a decrease in brake fluid pressure below a predetermined threshold value and a brake switch OFF during an idle stop. More specifically, the present invention relates to a countermeasure when a zero point drift of a brake hydraulic pressure sensor and an on-fixation of a brake switch occur.

  Conventionally, in an idling stop vehicle, the engine is stopped by idling the engine when the predetermined engine automatic stop condition is satisfied, and the engine restart condition indicates that the brake hydraulic pressure has become less than a predetermined threshold value during idling stop. (For example, refer to Patent Document 1 (paragraphs [0010], [0034], FIG. 1)).

  The predetermined engine automatic stop condition is that the vehicle speed is 0 km / h (stop), and the brake fluid pressure (master cylinder pressure), which is a brake force, is equal to or higher than a predetermined level.

Japanese Patent Laid-Open No. 11-27078

  By the way, in a recent idle stop vehicle, in order to further improve the fuel consumption by the idle stop, the engine automatic stop condition is satisfied during the deceleration (before the vehicle speed becomes 0 km / h). It has been proposed to further improve the above. In this case, if the permitted vehicle speed for idling stop is set to 7 km / h, for example, at least the vehicle speed is 7 km / h (stop) or less, and the brake fluid pressure (master cylinder pressure) as the brake force is 0.7 MPa or more, for example. The engine automatic stop condition is satisfied.

  The engine restart condition is that the brake fluid pressure is less than 0.1 MPa, for example.

  And in this kind of idle stop vehicle, in order to make the restart of the engine during the idle stop more reliable, as an engine restart condition, the above-described brake fluid pressure is reduced below a predetermined threshold value. Therefore, it is possible to adopt that either the brake fluid pressure has dropped below a predetermined threshold value or the brake switch (stop lamp switch) for detecting on / off of the brake has been turned off. It has been.

  On the other hand, a hydraulic pressure sensor (master cylinder pressure sensor) that detects the brake hydraulic pressure may output a higher output value (for example, 0.3 MPa although it is actually 0 MPa) due to a temperature rise or a zero point drift of secular change. In this case, even if the driver (user) tries to start by releasing the brake completely during the idle stop, the output value of the hydraulic pressure sensor does not fall below a predetermined threshold (for example, 0.1 MPa).

  When the output value of the hydraulic pressure sensor does not fall below a predetermined threshold value (for example, 0.1 MPa) due to zero point drift, the brake switch is mechanically turned on and fixed on for some reason. If so, the engine restart condition is that either the brake fluid pressure has fallen below a predetermined threshold or the brake switch that detects on / off of the brake has been turned off. However, there is a problem that the engine cannot be restarted.

  FIG. 4 shows changes in the vehicle state, the brake fluid pressure (master cylinder pressure) detected by the fluid pressure sensor, and the brake switch when the engine is restarted during idling stop under normal conditions, (a) is the vehicle state, (b) Is the brake fluid pressure, and (c) is the change in the brake switch.

  In this case, during idle stop, the master cylinder pressure detected by the hydraulic pressure sensor is sufficiently higher than a predetermined threshold (0.1 MPa), and the brake switch is on. In this state, when the driver releases the brake at the time ta in the figure (when the brake pedal is depressed), the brake fluid pressure detected by the fluid pressure sensor is lowered to a predetermined threshold value at time tb, and tc Sometimes the brake switch turns off and the engine restarts at tb.

  FIG. 5 shows the vehicle state and the hydraulic pressure sensor when the engine is restarted during an idle stop when the output value of the hydraulic pressure sensor is increased due to the zero point drift and the brake switch is mechanically stuck on for some reason. 4 shows changes in the brake fluid pressure (master cylinder pressure) and the brake switch detected by (1), as in FIG.

  In this case, during idle stop, the brake fluid pressure detected by the fluid pressure sensor is higher than normal, and there is no problem because the brake switch is fixed on. In this state, as in the case of FIG. 4, when the driver releases the brake at the time ta in the figure (when the brake pedal is stopped), the brake fluid pressure detected by the fluid pressure sensor as shown by the arrow line is high. Remains higher than a predetermined threshold and the brake switch is kept on so that the engine is not restarted.

  If the threshold value of the brake fluid pressure in the engine restart condition is set to a high value, for example, about 0.3 MPa, the above-described problem is unlikely to occur even if the zero point drift of the fluid pressure sensor occurs. From the viewpoint of preventing inadvertent engine restart, it is preferable that the threshold value of the brake fluid pressure in the engine restart condition is as low as possible, for example, 0.1 MPa. In addition, if the on / off state of the brake is detected by a plurality of brake switches, it is possible to detect the on / off state of the brake even when the on / off state of one system brake switch occurs. There is a problem that the number of parts increases and the cost becomes high.

  The present invention makes it possible to restart an engine that has been idle-stopped with a low-cost configuration even when the output value of the brake fluid pressure sensor is increased due to the zero point drift of the brake and the brake switch is fixed ON. For the purpose.

  In order to achieve the above-described object, the control device for the idle stop vehicle of the present invention stops the engine by idling when a predetermined engine automatic stop condition is satisfied, and is detected by the hydraulic pressure sensor during the idle stop. A control device for an idle stop vehicle that restarts an engine when an engine restart condition is satisfied, which includes at least one of a decrease in brake fluid pressure below a predetermined threshold and an off of a brake switch, wherein the brake switch Detecting means for detecting the state of the brake switch, and brake fluid pressure condition changing means for increasing the threshold value of the brake fluid pressure when the detecting means detects that the brake switch is continuously on. (Claim 1).

  Further, the control device for an idle stop vehicle according to the present invention is characterized in that the detection means detects the continuation of the ON state since it does not detect the brake switch OFF during the previous travel before the idle stop. (Claim 2).

  Furthermore, in the control device for an idle stop vehicle according to the present invention, after the brake hydraulic pressure condition changing means further raises the threshold value of the brake hydraulic pressure, the detecting means detects that the brake switch is turned off. Accordingly, a reset function for lowering the threshold value and returning the threshold value is provided (claim 3).

  According to the first aspect of the present invention, even if the brake switch is fixed on and the output of the hydraulic pressure sensor of the brake becomes a high output value due to the zero point drift, the detection means is in the on state of the brake switch. On the basis of this detection, the brake fluid pressure condition changing means increases the predetermined threshold value of the brake fluid pressure detected by the fluid pressure sensor based on this detection. If the driver releases the brake and the brake fluid pressure decreases, the engine that has been idle-stopped due to being less than the threshold value can be restarted even if the output value of the fluid pressure sensor is high.

  In addition, the predetermined threshold value of the brake fluid pressure detected by the fluid pressure sensor changes to a high value when the brake switch is fixed on, and does not increase from the beginning. The predetermined threshold value of the pressure can be set sufficiently low (for example, 0.1 MPa). This prevents the engine from being inadvertently restarted even if the driver accidentally loosens the brake pedal during idle stop.

  Furthermore, since it is not necessary to provide a plurality of brake switches, the number of parts is small, and the cost can be reduced.

  Accordingly, even when the output value of the hydraulic pressure sensor is increased due to the zero point drift and the brake switch is fixed on, the engine can be restarted with a low-cost configuration.

  According to the second aspect of the present invention, since the detection means does not detect the brake switch OFF during the previous travel before the idle stop, it can easily detect the brake switch ON fixation. .

  According to the third aspect of the present invention, if the brake fluid pressure detected by the brake fluid pressure sensor is increased by detecting the on-fixation and then the brake switch pressure is detected, the brake fluid pressure is detected. The threshold value can be automatically lowered and restored by the reset function of the condition changing means. As a result, by setting the predetermined threshold value low, for example, if the on-fixation of the brake switch is eliminated, even if the driver accidentally loosens the brake pedal during idle stop, the engine is inadvertently Is not restarted, and the idle stop control performance is further improved.

It is a block diagram of one embodiment of a vehicle control device of the present invention applied to an idle stop vehicle. 2 is a timing chart for explaining the operation of FIG. 1. It is a flowchart for operation | movement description of FIG. It is a timing chart of the normal control example of a conventional apparatus. It is a timing chart of the example of abnormal control of the conventional device.

  Next, in order to describe the present invention in more detail, an embodiment of the present invention will be described in detail with reference to FIGS.

  FIG. 1 shows a block configuration of a control device for an idle stop vehicle 1 to which the present invention is applied. 2 is a brake pedal, 3 is a master cylinder to which a pedal force of the brake pedal 2 is applied via a brake booster 4, and 5 is a master cylinder 3. A pipe 6 connected to the pipe 6 is a hydraulic pressure sensor (master cylinder pressure sensor) of the present invention attached to the pipe 5 and detects the master cylinder pressure. A brake actuator 7 includes a hydraulic pressure sensor 6 and a solenoid valve group 8.

  The solenoid valve group 8 includes a plurality of solenoid valves including brake fluid pressure control valves 8a and 8b. The brake fluid pressure control valves 8a and 8b are provided for each of, for example, two systems branched from the pipe 5, and are also used for idle stop and ABS (Antilock Brake System) brake control.

  9FL and 9FR are wheel cylinders for the left and right front wheels of the idle stop vehicle 1, and 9RL and 9RR are wheel cylinders for the left and right rear wheels of the idle stop vehicle 1, for example, one extending from the brake fluid pressure control valve 8a. The left front wheel cylinder 9FL and the right rear wheel cylinder 9RR are connected to the pipes 10FL, 10RR of this system, and the right front wheel cylinder 9FR is connected to the other pipes 10FR, 10RL extending from the brake fluid pressure control valve 8b. The wheel cylinder 9RL of the left rear wheel is connected.

  Next, the idle stop vehicle 1 is provided with an in-vehicle network 11 such as a CAN (Control Area Network). The in-vehicle network 11 includes an idle stop control ECU (eco-run control ECU) 12 and a brake control ECU ( (ABS control ECU) 13, engine control ECU 14, transmission control ECU 15, and the like are connected, and the ECUs 12 to 15 exchange information via the in-vehicle network 11.

  Each of the ECUs 12 to 15 is formed of a microcomputer and operates by being supplied with power from a vehicle-mounted 12V battery 16.

  The engine control ECU 14 controls a throttle opening degree of an engine (not shown), and the transmission control ECU 15 controls, for example, a belt type CVT (not shown).

  The idle stop control ECU 12 executes the set idle stop control program to form the detecting means and the brake hydraulic pressure condition changing means of the present invention. That is, the idle stop control ECU 12 obtains information on the brake fluid pressure (master cylinder pressure) detected by the fluid pressure sensor 6 based on communication with the brake control ECU 13 via the in-vehicle network 11 during traveling of the idle stove vehicle l. In addition to collecting, information on the engine speed of the engine control ECU 14, information on on / off of the IG ignition, vehicle speed, on / off of the brake switch (stop-run switch) 17, and the like are collected.

  The idle stop vehicle 1 according to the present embodiment satisfies the automatic engine stop condition during deceleration (during traveling before the vehicle speed becomes 0 km / h) while the permitted vehicle speed for idle stop is set to, for example, 7 km / h. An outline of the idle stop control is described as follows. After the engine of the idle stop vehicle 1 is started and turned on (operated) when the IG is on, the driver intends to stop the travel while the idle stop vehicle 1 is traveling. Then, when the accelerator pedal (not shown) is switched to the brake pedal 2 and a predetermined engine automatic stop condition is established, such as the vehicle speed is reduced to, for example, 7 km / h or less, the idle stop control ECU 12 A brake fluid pressure holding request is sent to the brake control ECU 13 via the network 11 and at the same time, the engine control ECU 14 is Sends a request to stop the engine of $ stop, based on the engine stop request, off engine control ECU14 it is automatically stopped engine, the idle stop vehicle 1 is in a state of idle stop.

  An example of the engine automatic stop condition is that the engine hood switch is turned on (closed), the door seat switch or door on the driver seat is turned on (closed), the shift position is the D range, the battery voltage is equal to or higher than the predetermined voltage, and at least the vehicle speed is 7 km / h (stop) or less, the master cylinder pressure detected by the hydraulic pressure sensor 6 becomes a predetermined stop threshold value (for example, 0.7 MPa) or more. During the idle stop, the brake pedal 2 is depressed, so the brake lamp is lit and the stop lamp switch 17 is turned on. The vehicle speed is detected by a four-wheel wheel speed sensor 18.

  When the driver continues to depress the brake pedal 2 even after the engine is automatically stopped, the brake force of the master cylinder pressure is applied to the wheel cylinders 9FL to 9RR, and the idle stop vehicle 1 decelerates and the traveling automatically stops. Becomes 0 km / h. Further, during idle stop, the wheel cylinders 9FL to 9RR maintain, for example, the brake fluid pressure immediately before the stop of travel and the driver continues to step on the brake pedal, so that the master cylinder pressure is maintained above the predetermined stop threshold. Be drunk.

  Next, when the driver releases the brake by releasing the brake pedal with the intention of starting during the idle stop, the brake hydraulic pressure detected by the hydraulic pressure sensor 6 in the idle stop state becomes a predetermined restart threshold value. (E.g., 0.1 MPa) or when the brake switch 17 is turned off, the engine restart condition includes at least one of lowering the brake hydraulic pressure to be lower than a predetermined threshold and turning off the brake switch 17 Is established, and the idle stop control ECU 12 sends a brake hydraulic pressure release request to the brake control ECU 13 via the in-vehicle network 11 and simultaneously sends an engine restart request to the engine control ECU 14. If the predetermined restart threshold value is set low, for example, to 0.1 MPa, the engine will not be inadvertently restarted even if the driver accidentally loosens the brake pedal 2 during idling stop. There are advantages. The engine restart condition is also satisfied when the driver depresses the accelerator pedal.

  Then, the engine control ECU 14 restarts the engine based on the engine restart request, and then the brake control ECU 13 releases the brake fluid pressure immediately before the traveling stop of the wheel cylinders 9FL to 9RR based on the brake fluid pressure release request, for example. The idle stop car 1 starts.

  Thereafter, the idle stop vehicle 1 repeats the idle stop of the engine automatic stop and the engine restart during the idle stop by the above-described idle stop control until the IG is turned off.

  Next, the detecting means and the brake hydraulic pressure condition changing means of the present invention formed by the idle stop control ECU 12 will be described.

  The detecting means always detects the on / off state of the brake switch 17.

  The brake fluid pressure condition changing means restarts the brake fluid pressure when the detecting means detects that the brake switch 17 is continuously on and the brake switch 17 is stuck on. The threshold value is raised to a set hydraulic pressure (for example, 0.4 MPa). In the case of the present embodiment, the brake fluid pressure condition changing means is one in which the on-sticking is eliminated when the detecting means detects that the brake switch 17 is turned off after raising the restart threshold value of the brake fluid pressure. And a reset function for lowering the restart threshold and restoring the original value.

  In the present embodiment, the continuation of the on state of the brake switch 17 is detected because the brake switch 17 is not detected to be off during the previous travel before the idling stop. The time when the vehicle is traveling last time is, for example, from the timing when the acceleration detected from the change in the vehicle speed becomes positive and the idle stop vehicle 1 with a vehicle speed of 0 km / h starts traveling, then the acceleration becomes negative and the vehicle speed becomes 0 km / h. Although it may be a period until the engine reaches h, in the present embodiment, in order to cope with the case where the driver steps on the accelerator pedal after the engine stops and before the traveling stops, When the engine is restarted, the acceleration detected from the change in the vehicle speed becomes positive and the idle stop vehicle 1 starts to travel until the next time the engine automatically stops. If the brake switch 17 is never turned off during this period, it is estimated that the brake switch 17 is stuck on. That is, the continuous detection of the ON state of the brake switch 17 during the previous travel is performed at least during a period including a travel period in which the acceleration before the idle stop is positive.

  Accordingly, when the engine is restarted during idling stop, the output of the hydraulic pressure sensor 6 is increased due to the zero point drift even though the brake switch 17 is fixed on and the driver releases the brake. For example, even if the pressure becomes only 0.3 MPa, which is higher than 0.1 MPa, the detection means detects that the brake switch 17 is stuck on during the previous travel, and based on this detection, the brake hydraulic pressure condition change means Since the restart threshold value of the brake fluid pressure detected by the fluid pressure sensor 6 is as high as 0.4 MPa, for example, the engine restart condition is satisfied and the engine is restarted.

  Further, after the restart threshold is increased to, for example, 0.4 MPa, when the detecting means detects that the brake switch 17 is turned off, the restart threshold automatically returns to the original predetermined 0.1 MPa. Therefore, the predetermined restart threshold value need not be set to a high value such as 0.3 MPa from the beginning in anticipation of the on-fixation of the brake switch 17. Therefore, even if the driver accidentally loosens the brake pedal 2 during idle stop, the engine will not be inadvertently restarted.

  FIG. 2 shows the vehicle of the idle stop vehicle 1 in which the output of the hydraulic pressure sensor 6 becomes a higher output value due to the zero point drift even though the brake switch 17 is fixed on and the driver releases the brake. Examples of changes in the state, vehicle speed, brake fluid pressure (master cylinder pressure) detected by the fluid pressure sensor 6 and the brake switch 17 are shown. (A) is the vehicle state, (b) is the brake fluid pressure, and (c) is the brake. This is a change of the switch 17. In addition, the solid line r in the brake fluid pressure of (b) shows the said restart threshold value.

  In this case, the predetermined restart threshold value is set to 0.1 MPa, and even if the driver releases the brake and indicates the intention to restart the engine at t1 during idling stop in the figure, the brake switch 17 is turned on. Since the sticking occurs and the brake fluid pressure detected by the fluid pressure sensor 6 becomes higher than 0.1 MPa due to the influence of the zero point drift, the engine does not restart, but the driver depresses the accelerator pedal. Suppose the engine is restarted and turned on.

  Then, the idle stop vehicle 1 starts at t2. Thereafter, when the driver starts stepping on the brake pedal 2 at t3 during traveling, the brake fluid pressure increases and the vehicle speed decreases. When the vehicle speed is at least 7 km / h or less at t4 and the brake fluid pressure exceeds the predetermined stop threshold value (0.7 MPa), the engine automatic stop condition is satisfied and the engine is automatically stopped and the idle stop vehicle. 1 enters an idle stop state. At this time, the brake hydraulic pressure condition changing means of the idle stop control unit 12 is not braked at any time during the previous travel from t2 to t4 because the detecting means has not detected the brake switch 17 being turned off. The restart threshold is raised to a set hydraulic pressure (0.4 MPa).

  When the driver releases the brake to start during this idle stop, and the brake fluid pressure falls below the restart threshold that is high at t5, even if the driver does not step on the accelerator pedal, The engine restart condition is satisfied and the engine restarts.

  Thereafter, when the brake switch 17 is not locked on at t6 and the detection means detects the brake switch 17 being turned off, the reset function of the brake hydraulic pressure condition changing means of the idle stop control unit 12 sets the restart threshold value. Return to the original 0.1 MPa.

  Further, after the restart threshold value returns to the original 0.1 MPa, when the driver depresses the brake pedal 2 at t7 while traveling, the brake switch 17 is turned on, and at t8, the brake fluid pressure becomes high and the engine automatic When the stop condition is satisfied, the engine automatically stops and the idle stop vehicle 1 enters the idle stop state. When the driver releases the brake at t9 during the idle stop, the brake switch 17 is turned off and the engine restart condition is satisfied. The engine restarts.

  Steps S1 to S8 in FIG. 3 show an example of the above-described idle stop control processing procedure of the idle stop control ECU 12. When the engine automatic stop condition is satisfied during traveling (YES in step S1), the engine is automatically stopped and the idle stop is performed. (Step S2). If the brake switch 17 has never been turned off during the previous run (NO in step S3), the restart threshold value is increased to 0.4 MPa by the brake hydraulic pressure condition changing means (step S4).

  When the engine restart condition is satisfied (YES in step S5) when the brake fluid pressure becomes less than 0.4 MPa, the brake switch 17 is turned off, or the accelerator pedal is depressed during idle stop. Is restarted (step S6).

  Further, after the restart threshold is increased to 0.4 MPa, if the brake switch 17 is turned off even once during the previous travel (YES in step S3), the brake fluid pressure condition changing means is restarted by the reset function. The threshold is returned to the original 0.1 MPa (step S7). In this case, the engine restart condition is satisfied when the brake hydraulic pressure is less than 0.1 MPa, the brake switch 17 is turned off, or the accelerator pedal is depressed during the idling stop (YES in step S8). Then, the engine is restarted (step S6).

  Therefore, in the case of the above-described embodiment, even if the brake switch 17 is fixed on and the output of the brake hydraulic pressure sensor 6 becomes a high output value due to the zero point drift, the driver releases the brake during the idle stop. If the brake fluid pressure decreases, the engine can be restarted.

  Further, since it is not necessary to increase the predetermined threshold value of the brake hydraulic pressure detected by the hydraulic pressure sensor 6 from the beginning, the predetermined restart threshold value of the brake hydraulic pressure detected by the hydraulic pressure sensor 6 is sufficiently low. Since it can be set to 0.1 MPa, even if the driver accidentally loosens the brake pedal 2 during idling stop, the engine will not be inadvertently restarted.

  Further, the brake switch 17 may be one system, and it is not necessary to provide a plurality of systems of brake switches. Therefore, the number of parts is small, and the cost can be reduced.

  Therefore, even when the output value is increased due to the zero point drift of the hydraulic pressure sensor 6 and the brake switch 17 is fixed ON, the engine can be restarted with a low-cost configuration.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit thereof. For example, the calculation means and detection means of the present invention May be provided in a control unit other than the idle stop control unit 12. Further, the predetermined stop threshold value and restart threshold value of the brake fluid pressure are not limited to 0.7 MPa and 0.1 MPa, and the increased restart threshold value is not limited to 0.4 MPa. Further, it goes without saying that the configuration of each part of the idle stop vehicle 1 may be different from that shown in FIG.

  Next, the permitted vehicle speed for idle stop is not limited to the above-mentioned 7 km / h, and may be an appropriate vehicle speed, and the present invention can be applied even when the permitted vehicle speed for idle stop is 0 km / h (stop). Of course. Of course, the processing procedure of the idle stop control ECU 12 may be different from that shown in FIG. Further, in the above embodiment, the on-state continuity (fixed on) of the brake switch 17 is detected because the detecting means has never detected the brake switch 17 off during the previous run. The continuation of the ON state of the brake switch 17 (fixed on) may be detected from the fact that the brake switch 17 is ON, for example, by failure diagnosis.

  The present invention can be applied to various idle stop vehicle control devices including at least an engine as a driving force source.

1 Idle stop vehicle 6 Fluid pressure sensor 12 Idle stop control ECU
17 Brake switch

Claims (3)

When the predetermined engine automatic stop condition is satisfied, the engine is stopped and idle stopped. During the idle stop, the brake fluid pressure detected by the fluid pressure sensor is reduced below a predetermined threshold value, and at least the brake switch is turned off. A control device for an idle stop vehicle that restarts the engine when an engine restart condition including any of them is established,
Detecting means for detecting a state of the brake switch;
A brake fluid pressure condition changing means for increasing the threshold value of the brake fluid pressure when the detection means detects that the brake switch is continuously on. Control device. In the control apparatus of the idle stop vehicle according to claim 1,
The control means for detecting an idling stop vehicle, wherein the detecting means detects the continuation of the on state since the brake switch is not detected to be off during the previous travel before the idling stop. In the control apparatus of the idle stop vehicle according to claim 1 or 2,
The brake fluid pressure condition changing means further has a reset function for raising the threshold value of the brake fluid pressure and then lowering the threshold value when the detecting means detects that the brake switch is turned off. An idle stop vehicle control device comprising:

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