JP2017008737A - Idling stop control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly perform idling stop control even if an accumulator is in a low accumulation pressure state.SOLUTION: Since an engine stoppable time Tis is set on the basis of accumulator pressure (pressure accumulation state) Pacc, and idling stop control is performed with the stoppable time Tis as an upper limit, even if the accumulator pressure Pacc is low, that is, the accumulator pressure is not max pressure, fuel economy can be improved by performing the idling stop control while avoiding the lack of the hydraulic pressure of the accumulator at a restart of an engine.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an idling stop control device for a vehicle, and more particularly to a technique capable of appropriately performing idling stop control regardless of the pressure accumulation state of an accumulator.

  (a) an engine that is used as a driving force source for traveling; (b) a mechanical oil pump that is rotationally driven by the engine; and (c) an accumulator that is connected to the mechanical oil pump and accumulates pressure. Regarding a vehicle, (d) an idling stop control device that automatically stops the rotation of the engine under a certain condition and releases the hydraulic pressure by releasing the accumulator when the engine is restarted is known. The device described in Patent Document 1 is an example, and when the accumulator is in a low pressure accumulation state, idling stop control is performed after accumulating pressure in the accumulator.

JP 2010-151238 A

  However, when accumulating pressure prior to the idling stop control in this way, the start time of the idling stop control is delayed, so that the fuel efficiency improvement effect by the idling stop control may be impaired accordingly.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to enable appropriate idling stop control even when the accumulator is in a low pressure accumulation state.

  The present invention includes (a) an engine used as a driving force source for traveling, (b) a mechanical oil pump that is rotationally driven by the engine, and (c) an accumulator that is connected to the mechanical oil pump and accumulates pressure. (D) an idling stop control device that automatically stops the rotation of the engine under a certain condition and releases the hydraulic pressure by releasing the accumulator when the engine is restarted. ) The engine stoppable time is set based on the pressure accumulation state of the accumulator, and the engine is stopped from rotation with the stoppable time as an upper limit.

  In such a vehicle idling stop control apparatus, when the accumulator pressure accumulation state is set, the engine stoppable time is set, and the engine is stopped with the stoppable time as an upper limit, so the accumulator pressure accumulation state is low However, idling stop control can be performed to improve fuel efficiency while avoiding insufficient hydraulic pressure in the accumulator when the engine is restarted. That is, when the engine is stopped, the accumulated pressure state of the accumulator gradually decreases due to leakage (leakage), and by limiting the engine stop time according to the accumulated pressure state in consideration of the amount of leakage, even when the accumulated pressure state is low, The idling stop control can be performed while avoiding insufficient hydraulic pressure at the time of restart regardless of the leak. In addition, since the engine is restarted after the stoppable time elapses, there is a possibility that the idling stop time is shortened and the fuel efficiency improvement effect may be impaired, but the idling is performed by releasing the brake operation within the stoppable time. When the stop control is completed, the fuel efficiency improvement effect by the idling stop control can be appropriately obtained, so that the fuel efficiency performance can be expected to improve as a whole.

1 is a hydraulic circuit diagram for explaining a vehicle hydraulic control apparatus to which the present invention is applied, and also shows a main part of a control system. FIG. It is a flowchart explaining the pressure accumulation control of the accumulator performed by the pressure accumulation control part of FIG. It is an example of the time chart which showed the change of the line pressure PL and the accumulator pressure Pacc when accumulator control is performed according to the flowchart of FIG. 2 with the change of the counters C0-C2. It is a flowchart explaining the idling stop control performed by the idling stop control part of FIG. FIG. 5 is a diagram for explaining engine stoppable times Tmax and Tmid set according to the accumulator pressure Pacc in R3 to R8 of the flowchart of FIG. It is a flowchart explaining another example of the pressure accumulation control of the accumulator performed by the pressure accumulation control part of FIG. It is an example of the time chart which showed the change of the line pressure PL and the accumulator pressure Pacc when the pressure accumulation control is performed according to the flowchart of FIG. 6 together with the pressure accumulation amount accumulated value and the change in the vehicle speed.

  The accumulator pressure accumulation state is the accumulator pressure or piston position, that is, the amount of accumulated oil, etc., which can be detected directly by the sensor, etc., but the accumulated pressure amount is sequentially calculated by setting the accumulated pressure to the accumulator as + and leak as-. The accumulated pressure accumulated value can be used instead of the accumulator pressure or the accumulated oil amount. The accumulated pressure amount and the leak amount can be estimated from the differential pressure between the accumulated pressure amount corresponding to the accumulator pressure and the line pressure.

  The engine stoppable time takes into account the leakage of the accumulator, and is set by a predetermined map, arithmetic expression, or the like so that it is longer when the accumulator pressure accumulation state is high than when it is low. This stoppable time may be changed stepwise in, for example, two steps or three or more steps, but can also be changed continuously in a straight line or a curved line.

  If the accumulator pressure accumulation state is less than the predetermined value, that is, if the accumulator pressure at the time of restart cannot be adequately secured even if the engine stoppage time is shortened, idling stop control is prohibited, or patent literature It is desirable to perform idling stop control after performing accumulator pressure accumulation control as in 1.

  The hydraulic pressure output from the mechanical oil pump is supplied to the hydraulic actuator via a supply oil passage, and an accumulator is connected to the supply oil passage. The hydraulic actuator is operated based on hydraulic pressure, such as a hydraulic friction engagement device such as a hydraulic clutch or brake, or a belt-type continuously variable transmission whose transmission ratio and clamping pressure are controlled based on hydraulic pressure. It is. And between the said supply oil path and the accumulator, for example, it accumulates in an accumulator via a 1st oil path, and the oil connection area is larger than the 1st oil path which can hold | maintain in a pressure accumulation state A switching valve that is switched by electric control is provided in a second connection state in which the accumulator and the supply oil passage are communicated with each other via the second oil passage and the hydraulic pressure of the accumulator can be supplied to the hydraulic actuator. As this switching valve, an electromagnetic switching valve for switching the oil passage by moving the spool by the suction force of the solenoid is preferably used. In the first oil passage, for example, a check valve that allows the flow of hydraulic oil from the supply oil passage to the accumulator side but prevents the reverse flow and a throttle having a predetermined oil passage area are provided in series. However, an electromagnetic on-off valve can be provided in place of the check valve to maintain the accumulator pressure accumulation state, or the flow path itself can be made narrow without providing a throttle.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a hydraulic circuit diagram illustrating a vehicle hydraulic control apparatus 10 to which the present invention is applied, and includes a mechanical oil pump 14 that is rotationally driven by an engine 12. The engine 12 is used as a driving force source for running a vehicle, and is an internal combustion engine that generates power by burning fuel. The mechanical oil pump 14 pumps hydraulic oil from the oil pan 16 and outputs it to the line pressure control oil passage 18. The line pressure control oil passage 18 is provided with a line pressure control valve 20 and an electromagnetic pressure regulating valve 22, and a control oil pressure SP regulated by the electromagnetic pressure regulating valve 22 according to the command current Islt is applied to the line pressure control valve 20. Thus, the line pressure PL is controlled in accordance with the command current Islt.

  A supply oil passage 26 is connected to the line pressure control oil passage 18 via a check valve 24. The supply oil passage 26 has a valve body 27 having an electromagnetic switching valve, an electromagnetic on-off valve, an electromagnetic pressure regulating valve, and the like. A hydraulic actuator 28 is connected via The hydraulic actuator 28 is a hydraulic friction engagement device such as a hydraulic clutch or a brake provided in a transmission mechanism such as a stepped transmission or a forward / reverse switching device. The hydraulic actuator 28 is frictionally engaged by hydraulic pressure. By combining, for example, a plurality of forward gears are established, or a forward drive state or a reverse drive state is established, and the vehicle can travel. In this embodiment, idling stop control is performed to automatically stop the rotation of the engine 12 when the vehicle is stopped, etc., and the hydraulic pressure supply to the hydraulic actuator 28 is stopped and released, thereby neutralizing power transmission. It becomes a state.

  A branch oil passage 30 is provided in the supply oil passage 26, and an accumulator (Acc) 34 is connected via an electromagnetic switching valve 32. The accumulator 34 quickly supplies hydraulic oil to the hydraulic actuator 28 when the engine 12 is restarted upon completion of the idling stop control, and promptly engages the hydraulic actuator 28 to This is so that the vehicle can start quickly. The accumulator 34 is configured to accumulate hydraulic oil while retreating the piston against a biasing force of a biasing device such as a spring, and to push the hydraulic oil forward by the piston according to the biasing force of the biasing device. The accumulator pressure Pacc, which is the hydraulic pressure of the accumulated hydraulic oil, increases as the piston moves backward, that is, the amount of accumulated oil increases. It is also possible to employ an accumulator capable of controlling the back pressure that can adjust the accumulator pressure Pacc.

  The electromagnetic switching valve 32 switches the oil path by moving the spool with the suction force generated by the excitation of the solenoid. When not energized, the electromagnetic switching valve 32 is in a first connection state in which pressure is accumulated in the accumulator 34 via the first oil path 36. In some cases, the accumulator 34 and the supply oil passage 26 are connected via the second oil passage 38, and the accumulator 34 is opened so that the hydraulic oil is supplied to the hydraulic actuator 28. The first oil passage 36 has a check valve 40 that permits the flow of hydraulic oil from the supply oil passage 26 to the accumulator 34 side but prevents the reverse flow, and the oil passage area ψ 1 has a second oil passage 38. A throttle 42 smaller than the oil passage area ψ 2 is provided in series, and the hydraulic pressure in the supply oil passage 26, that is, the line pressure PL is suppressed from being lowered by the action of the throttle 42 when accumulating the accumulator 34. The accumulated pressure state of the accumulator 34 is maintained by the action of the stop valve 40. On the other hand, when the solenoid is switched to the second connected state by energizing the solenoid by energization, the accumulator 34 and the supply oil passage 26 are communicated with each other via the second oil passage 36 having a large oil passage area ψ2, and the accumulator 34 is opened. By releasing the internal hydraulic pressure, the hydraulic oil in the accumulator 34 is quickly supplied to the hydraulic actuator 28, and the hydraulic actuator 28 is quickly engaged. The electromagnetic switching valve 32 is not energized in the normal traveling state in which the engine 10 is operating, and is maintained in the first connection state shown in FIG. 1 according to the urging force of the spring 44.

  Such a hydraulic control device 10 includes an electronic control device 50 for hydraulic control as a controller for controlling the electromagnetic pressure regulating valve 22, each electromagnetic valve of the valve body 27, and the electromagnetic switching valve 32. The hydraulic control electronic control device 50 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like, and performs a signal processing in accordance with a predetermined program, thereby providing a line pressure control unit. 52, the pressure accumulation control unit 54, and the idling stop control unit 56 are executed. The hydraulic control electronic control unit 50 includes an accelerator pedal operation amount (accelerator operation amount) αac, brake operation presence / absence Br, engine 12 throttle valve opening θth, vehicle speed V, line pressure PL, accumulator pressure Pacc, etc. Various information necessary for the control is supplied from a sensor or the like.

  The line pressure control unit 52 regulates the control hydraulic pressure SP by outputting the command current Islt to the electromagnetic pressure regulating valve 22 based on the accelerator operation amount αac, the vehicle speed V, and the like, and the line pressure PL via the line pressure control valve 20. To control. This line pressure PL is controlled to be as low as possible in order to improve fuel consumption. The pressure accumulation control unit 54 performs pressure accumulation control for holding the accumulator 34 in a predetermined pressure accumulation state in preparation for idling stop control. For example, the pressure accumulation control unit 54 performs signal processing according to the flowchart of FIG. The idling stop control unit 56 controls the stoppable time of the engine 12 according to the accumulator pressure Pacc when the engine 12 is automatically stopped when the vehicle is stopped. For example, according to the flowchart of FIG. Execute. These line pressure control unit 52, pressure accumulation control unit 54, and idling stop control unit 56 can also be expressed as line pressure control means, pressure accumulation control means, and idling stop control means, respectively.

  The flowchart of FIG. 2 executed by the pressure accumulation control unit 54 includes a plurality of steps indicated by S1 to S16. In S1, it is determined whether or not the pressure accumulation completion flag Foil is ON. If OFF, S2 is executed. If ON, S5 is executed, but S2 is executed because the control is initially OFF. In S2, it is determined whether or not the vehicle is decelerating based on the change in the vehicle speed V. If the vehicle is decelerating, the command current Islt is set as the pressure accumulation current value in S3. That is, by increasing the line pressure PL using the command current Islt as an accumulating current value when the vehicle is decelerated, the accumulator 34 accumulates pressure quickly while suppressing the influence on fuel efficiency. The line pressure control by S3 is executed in preference to the line pressure control by the line pressure control unit 52. FIG. 3 is an example of a time chart when the pressure accumulation control is performed according to the flowchart of FIG. 2. At time t1, the determination of S2 is YES (affirmed), and the command current Islt is switched to the pressure accumulation current value at S3. Time. In next S4, the counter C1 for measuring the pressure accumulation time is counted up. The counter C1 measures the elapsed time after the line pressure PL reaches the hydraulic pressure corresponding to the current value for pressure accumulation, that is, the target line pressure during pressure accumulation, and at time t2 in FIG. 3, the counter C1 starts counting up. It's time.

  If the determination in S2 is NO (No), that is, if the vehicle is not decelerating, the command current Islt is set to a normal value in S7, and the line pressure control by the line pressure control unit 52 is performed as it is. In the next S8, the counters C1 and C2 are both reset to zero. The counter C2 is for measuring the re-accumulation time, and measures the elapsed time after the line pressure PL reaches the target line pressure during accumulation during the re-accumulation.

  In S12, it is determined whether the counter C1 is equal to or greater than the pressure accumulation completion determination value C1s or whether the counter C2 is equal to or greater than the re-accumulation completion determination value C2s. At the beginning of the pressure accumulation control, all are NO, S15 is executed following S12, and S1 and subsequent steps are repeatedly executed. When S3 and S4 are repeatedly executed during deceleration of the vehicle, hydraulic oil flows into the accumulator 34 based on the high line pressure, and the accumulator pressure Pacc increases as shown in FIG. growing. The pressure accumulation completion determination value C1s is a pressure accumulation time (for example, about 5 seconds) until the accumulator pressure Pacc becomes sufficiently higher than a predetermined pressure required for return, and when the counter C1 reaches the pressure accumulation completion determination value C1s, The determination in S12 is YES, the pressure accumulation completion flag Foil is turned ON in S13, and the counter C0 is reset to 0 in S14. The counter C0 is for measuring the elapsed time after completion of pressure accumulation. The time t3 in FIG. 3 is the time when the counter C1 reaches the pressure accumulation completion determination value C1s and the determination in S12 is YES. Note that the time when the command current Islt is switched to the pressure accumulation current value by setting the pressure accumulation completion determination value C1s in consideration of the rise time of the command current Islt, the response delay of the line pressure PL, and the like (time in FIG. 3). The counter C1 may start counting up starting from t1). Further, it is also possible to determine whether or not to accumulate pressure by detecting or estimating the accumulator pressure Pacc without using the counter C1.

  When the pressure accumulation completion flag Foil is turned on in S13, the determination in S1 is YES from the next control cycle, and S5 is executed following S1. In S5, the counter C0 is counted up, and in the next S6, it is determined whether or not the counter C0 is equal to or greater than the re-accumulation determination value C0s. Since C0 <C0s immediately after the completion of pressure accumulation, the determination in S6 is NO, the command current Islt is set to the normal value in S7, and the line pressure PL is reduced to the normal value. Subsequent to S8, S12, and S15, S1 and the subsequent steps are repeatedly executed, and the counter C0 is sequentially counted up in S5. Even if the line pressure PL becomes lower than the accumulator pressure Pacc, the accumulator 34 is maintained in the accumulated state by the check valve 40, but a leak occurs depending on the differential pressure ΔP between the accumulator pressure Pacc and the line pressure PL, and the accumulator pressure Pacc gradually decreases. The re-accumulation determination value C0s is determined so that re-accumulation is performed before the accumulator pressure Pacc becomes lower than the required pressure at the time of recovery in consideration of the decrease in the accumulator pressure Pacc due to this leak, and the idling stop control is executed. If the counter C0 reaches the re-accumulation determination value C0s and the determination in S6 becomes YES without being performed, S9 and subsequent steps are executed for re-accumulation. The time t4 in FIG. 3 is the time when the counter C0 reaches the re-accumulation determination value C0s and the determination in S6 becomes YES. The counter C0 has a re-accumulation determination value C0s as an upper limit value, and is held at C0s until the re-accumulation is completed. Note that the reaccumulation determination can be made by detecting or estimating the accumulator pressure Pacc without using the counter C0.

  In S9, it is determined whether or not the vehicle is decelerating as in S2. If the vehicle is not decelerating, S7 and S8 are executed. If the vehicle is decelerating, S10 is executed, and as in S3. The command current Islt is set as a current value for pressure accumulation. Thereby, it is possible to quickly accumulate pressure in the accumulator 34 while suppressing the influence on the fuel consumption performance. In next S11, the counter C2 for measuring the re-accumulation time is counted up. Similarly to the counter C1, the counter C2 measures the elapsed time after the line pressure PL reaches the hydraulic pressure corresponding to the accumulated current value, that is, the accumulated target line pressure, and the time t5 in FIG. 3 is counted by the counter C2. It is the time when up starts. FIG. 3 shows a case where the vehicle is decelerating when the counter C0 reaches the re-accumulation determination value C0s, and the pressure accumulation control in S10 is immediately started.

  When S10 and S11 are repeatedly executed, the hydraulic oil flows into the accumulator 34 based on the high line pressure, the accumulator pressure Pacc increases, and the counter C2 increases. The re-accumulation completion determination value C2s of S12 is an accumulator time until the accumulator pressure Pacc becomes sufficiently higher than a predetermined required pressure at the time of return, but is compared with the first accumulator control (S3, S4). Since the pressure Pacc is high, a time shorter than the pressure accumulation completion determination value C1s, for example, about 1 second is set. However, if the vehicle is not decelerating and the command current Islt is set to a normal value in S7 and the line pressure PL is held at a low pressure, the accumulator pressure Pacc is reduced to a pressure lower than the required pressure at the time of restoration, so when the pressure accumulation is completed (see FIG. 3, the re-accumulation completion determination value C <b> 2 s is set according to a map, an arithmetic expression, and the like based on the elapsed time from the time t <b> 3) until the re-accumulation of S <b> 10 starts. When S9 is omitted and the counter C0 reaches the re-accumulation determination value C0s, the re-accumulation completion determination value C2s is set to a constant value if S10 is always executed regardless of whether the vehicle is decelerating or not. It may be fixed to. When the counter C2 reaches the re-accumulation completion determination value C2s, the determination in S12 is YES, the accumulation completion flag Foil is turned on in S13, and the counter C0 is reset to 0 in S14. The time t6 in FIG. 3 is a time when the counter C2 reaches the re-accumulation completion determination value C2s and the determination in S12 becomes YES. Also for the counter C2, by setting the re-accumulation completion determination value C2s in consideration of the rise time of the instruction current Islt, the response delay of the line pressure PL, etc., the time when the instruction current Islt is switched to the accumulator current value Counting up may be started from (time t4 in FIG. 3) as a starting point. Further, the reaccumulation completion determination can be made by detecting or estimating the accumulator pressure Pacc without using the counter C2.

  When the counter C0 is reset to 0 in S14, the determination in S6 is NO from the next control cycle, S7 is executed following S6, the command current Islt is set to the normal value, and the line pressure PL is set to the normal value. Reduced. FIG. 3 shows a case where the vehicle is stopped and idling stop control is started at time t7 after the completion of the re-accumulation. During the idling stop control, S5 and subsequent steps are executed following S1, but since the vehicle is stopped, the command current Islt is set to the normal value and the line pressure PL is set to 0 (atmospheric pressure) in S7. For this reason, the accumulator pressure Pacc gradually decreases due to the leak, but at the start of the idling stop control, it is basically higher than the required pressure at the time of return, so the electromagnetic switching valve 32 is brought into the second connection state at the end of the idling stop control. By switching, the hydraulic oil of the accumulator 34 is quickly supplied to the hydraulic actuator 28. When the idling stop control is completed, the determination in S15 is YES, and the accumulation pressure completion flag Foil is turned off in S16, so that in the subsequent control cycle, S2 and subsequent steps are executed, and the accumulation control is performed again. Be started.

  The flowchart of FIG. 4 executed by the idling stop control unit 56 includes a plurality of steps indicated by R1 to R15. In R1, it is determined whether or not the engine 12 is idling stopped. If idling is stopped, R11 or less is executed, but if idling is not being stopped, R2 or less is executed. In R2, it is determined whether or not an idling stop control execution condition is satisfied. The execution condition of the idling stop control is when the possibility of immediately starting the vehicle is low, for example, the vehicle speed V is equal to or lower than a predetermined value and the brake is operated. If the execution condition is satisfied, R3 is executed to determine whether or not the accumulator pressure Pacc representing the pressure accumulation state of the accumulator 34 is the maximum pressure. In the accumulator 34, the accumulator pressure Pacc increases in accordance with the retraction amount of the piston, and the accumulator pressure Pacc in the state of reaching the retreat end is the max pressure. When Pacc = max pressure, the maximum time as the stop possible time Tis is R4. Set Tmax. FIG. 5 shows an example of a change characteristic of the accumulator pressure Pacc due to leakage when the engine 12 is stopped at time t1 and the line pressure PL is set to 0 when the accumulator pressure Pacc is the maximum pressure. Assuming that the time required for the return to the required pressure is t3, the time from t1 to t3 is the maximum time Tmax, and a predetermined value is determined in advance with a predetermined margin through experiments or the like.

  When the determination of R3 is NO, that is, when the accumulator pressure Pacc is not the maximum pressure, it is determined whether or not it is higher than the required pressure at the time of return at R5. The intermediate time Tmid is set as follows. This intermediate time Tmid is a time during which the accumulator pressure Pacc decreases to the required pressure at the time of return when the line pressure PL is set to 0, and is set in advance by a data map or the like using the accumulator pressure Pacc as a parameter based on the change characteristics shown in FIG. Is done. FIG. 5 shows an intermediate time Tmid in the case of the accumulator pressure Pacc at time t2. This intermediate time Tmid is also determined with a predetermined margin so that the accumulator pressure Pacc is maintained at a pressure higher than the required pressure at the time of return. The accumulator pressure Pacc can also be detected by a hydraulic pressure sensor. For example, the accumulator pressure Pacc is calculated (estimated) by obtaining the leak amount from the differential pressure from the line pressure PL and the elapsed time and subtracting the leak amount from the max pressure. You can also.

  When the determination of R5 is NO, that is, when the accumulator pressure Pacc is equal to or lower than the required pressure at the time of return, the accumulator 34 is forcibly accumulated in R7, and then the maximum time Tmax is set as the stoppable time Tis in R8. The forced pressure accumulation of R7 is performed by increasing the line pressure PL using the command current Islt as the current value for pressure accumulation, for example, as in S2 of FIG. This forced pressure accumulation is performed in preference to the line pressure control by the line pressure control unit 52. The time t3 in FIG. 5 is the time when the forced pressure accumulation of R7 is started, and is quickly increased to the accumulator pressure Pacc by the high line pressure PL to the max pressure. 2 is performed, the accumulator pressure Pacc is normally maintained at a pressure higher than the required pressure at the time of return. However, if the deceleration time is short, such as during a sudden stop immediately after return from idling stop, the accumulator pressure Pacc. There is a possibility that the pressure Pacc may be less than the required pressure at the time of return. If the accumulator pressure Pacc is equal to or lower than the required pressure at the time of return as described above, the idling stop control may be stopped without executing R7 and R8.

  In the next R9, an idling stop command is output to the engine control electronic control device 60 to stop fuel injection and stop the engine 12 from rotating. If necessary, the hydraulic actuator 28 may be opened to achieve a neutral state where power transmission is interrupted. In the next R10, the counter Cis for measuring the idling stop time is reset to zero.

  When the idling stop control is started in R9, the determination of R1 is YES from the next control cycle, and R11 and subsequent steps are executed. In R11, it is determined whether or not an idling stop control end condition is satisfied. The end condition of the idling stop control is when the possibility of starting the vehicle becomes high, for example, when the brake operation is released. When the end condition is satisfied, the end process of the idling stop control of R12 and R13 is executed. In R12, the engine 12 is restarted by cranking, fuel injection, or the like by outputting an engine restart command to the engine control electronic control unit 60. In R13, the electromagnetic switching valve 32 is switched from the first connection state to the second connection state, and the accumulator 34 is communicated with the supply oil passage 26 via the second oil passage 38, so that the hydraulic oil in the accumulator 34 is discharged. Immediately supplied to the hydraulic actuator 28.

  If the determination of R11 is NO, that is, if the end condition for the idling stop control is not satisfied, R14 is executed and the counter Cis for measuring the idling stop time is counted up. In the next R15, it is determined whether or not the counter Cis has reached the stoppable time Tis. If Cis <Tis, the process ends and repeats execution after R1, but if Cis ≧ Tis, R12 and R13 is executed and the idling stop control is terminated. When the counter Cis reaches the stoppable time Tis, the accumulator pressure Pacc is equal to or higher than the required pressure at the time of return, so that the hydraulic actuator 28 can be appropriately engaged by the hydraulic pressure in the accumulator 34.

  As described above, in the idling stop control of the present embodiment, the stop possible time Tis of the engine 12 is set based on the accumulated state of the accumulator 34, specifically, the accumulator pressure Pacc, and the idling stop is set with the stop possible time Tis as the upper limit. Since the control is performed, even when the accumulator pressure Pacc is low, that is, when it is not the maximum pressure, the idling stop control can be performed to improve fuel efficiency while avoiding insufficient hydraulic pressure of the accumulator 34 when the engine 12 is restarted. . That is, when the engine is stopped, the accumulator pressure Pacc gradually decreases due to a leak (leakage). Therefore, the accumulator is limited by limiting the stop time (idling stop time) of the engine 12 according to the accumulator pressure Pacc in consideration of the amount of the leak. Even when the pressure Pacc is low, the idling stop control can be performed while avoiding insufficient hydraulic pressure at the time of engine restart regardless of the leak. Further, since the engine 12 is restarted when the stoppable time Tis is reached, there is a possibility that the idling stop time is shortened and the fuel efficiency improvement effect may be impaired, but the brake operation is released within the stoppable time Tis. When the idling stop control is completed, the fuel efficiency improvement effect by the idling stop control can be appropriately obtained, so that it can be expected that the fuel efficiency is improved as a whole.

Next, another embodiment of the present invention will be described.
FIG. 6 is a flowchart of the pressure accumulation control executed by the pressure accumulation control unit 54 instead of FIG. 2, and FIG. 7 is an example of a time chart when the pressure accumulation control is performed according to the flowchart of FIG. The flowchart of FIG. 6 includes a plurality of steps indicated by Q1 to Q13. In Q1, it is determined whether or not the vehicle is decelerating. And if it is decelerating, the pressure accumulation control of Q2-Q6 will be performed, but if it is not decelerating, the accumulation step of Q7-Q11 will be performed immediately, without performing the pressure accumulation control of Q2-Q6. The period of time t4 to t6 in FIG. 7 is when the vehicle is decelerating, and during that period, the pressure accumulation control of Q2 to Q6 is executed, but during other constant speeds or accelerations, the pressure accumulation control is not executed without executing the pressure accumulation control. The calculation step of the accumulated pressure accumulation value of Q11 is executed.

  In Q7, it is determined whether or not the command current Islt is larger than a converted value Iacc_chrg of the accumulated pressure amount. The command current Islt is a parameter corresponding to the line pressure PL, and is read from the line pressure control unit 52 as necessary. The accumulated pressure accumulation value is a parameter corresponding to the accumulator pressure Pacc. In this embodiment, the accumulated pressure amount is sequentially calculated in steps Q7 to Q11 for each control cycle. The converted value Iacc_chrg is a value obtained by converting the accumulated pressure accumulation value into the command current Islt, and a map and an arithmetic expression for calculating the converted value Iacc_chrg using the accumulated pressure accumulation value as a parameter are determined in advance. Islt> Iacc_chrg means that the line pressure PL is larger than the accumulator pressure Pacc and the accumulator pressure Pacc is increased based on the line pressure PL. In Q8, the converted value Iacc_chrg is subtracted from the command current Islt. The deviation is integrated by time (cycle time) to calculate the pressure accumulation amount, that is, the increase amount of the accumulator pressure Pacc. In Q9, a new accumulated pressure accumulation value corresponding to the current accumulator pressure Pacc is calculated by adding the accumulated pressure amount to the accumulated pressure accumulation value.

  If the determination of Q7 is NO, that is, if Islt ≦ Iacc_chrg, it means that the line pressure PL is less than or equal to the accumulator pressure Pacc, and the hydraulic oil in the accumulator 34 leaks to reduce the accumulator pressure Pacc. Therefore, in Q10, the leak amount is calculated by integrating the deviation obtained by subtracting the command current Islt from the converted value Iacc_chrg with time (cycle time). In Q11, a new accumulated pressure accumulation value corresponding to the current accumulator pressure Pacc is calculated by subtracting the leak amount from the accumulated pressure accumulation value.

  The period from time t1 to t4 in FIG. 7 is a constant speed or acceleration state, and the line hydraulic pressure PL is controlled by the line pressure control unit 52 based on the accelerator operation amount αac, the vehicle speed V, etc. By increasing the line pressure PL, PL> Pacc is satisfied in the period of time t1 to t3 including the acceleration time. Therefore, during the period of time t1 to t3, the determination of Q7 is YES, and the accumulated pressure value is increased by executing Q8 and Q9. In the subsequent period from time t3 to t4, since PL <Pacc, the determination of Q7 is NO, and the accumulated pressure value is decreased by executing Q10 and Q11.

  On the other hand, during time t4 to t6 when the vehicle is decelerated, the pressure accumulation control of Q2 to Q6 is executed prior to the calculation of the accumulated pressure amount. In Q2, it is determined whether or not the accumulated pressure accumulation value corresponding to the accumulator pressure Pacc is equal to or greater than a predetermined accumulated pressure determination value. The accumulated pressure completion determination value is a value corresponding to a hydraulic pressure value sufficiently higher than the required pressure at the time of return, and if the accumulated pressure amount accumulated value ≧ the accumulated pressure completion determination value, it is not necessary to accumulate more pressure. Islt is set to a normal value, and the line pressure control by the line pressure control unit 52 is performed as it is. If the accumulated pressure accumulation value is lower than the accumulated pressure completion determination value, it is determined in Q4 whether or not the accumulated pressure accumulation value is greater than or equal to a predetermined rapid accumulation pressure determination value. The rapid pressure accumulation determination value is a value corresponding to a hydraulic pressure value lower than the required pressure at the time of return, and if the accumulated pressure amount accumulated value ≧ the rapid pressure accumulation determination value, the command current Islt is set to the pressure accumulation current value in Q5, and the line pressure control unit The command current Islt is output in preference to the line pressure control by 52, whereby the line pressure PL is increased to the target line pressure during accumulation, and hydraulic oil flows into the accumulator 34 and accumulates it.

  If the determination in Q4 is NO, that is, if the accumulated pressure accumulation value is lower than the rapid accumulation determination value, the command current Islt is set to the rapid accumulation current value in Q6, giving priority to the line pressure control by the line pressure control unit 52. When the command current Islt is output, the line pressure PL is increased to the target line pressure at the time of rapid pressure accumulation that is higher than the target line pressure at the time of pressure accumulation, and the hydraulic oil rapidly flows into the accumulator 34 and is quickly accumulated. . In FIG. 7, at time t4 when the vehicle is decelerated, the accumulated pressure accumulation value is lower than the rapid accumulation determination value, so the line pressure PL is increased to the target line pressure during rapid accumulation, and accumulator pressure Pacc is accordingly increased. Raised rapidly. When the accumulated pressure accumulation value reaches the accumulated pressure determination value at time t5, the determination of Q2 is YES, the command current Islt is returned to the normal value, and the line pressure control unit 52 controls the line pressure PL. Become. When the command current Islt is set to the rapid pressure accumulation current value in Q6, the rapid pressure accumulation current value is maintained until the judgment of Q2 becomes YES regardless of the subsequent judgment result of Q4.

  In FIG. 7, the idling stop control is started at time t6 when the vehicle speed V becomes substantially zero due to deceleration, the engine 12 is stopped and the line pressure PL becomes zero. Further, when the idling stop control is terminated by releasing the brake operation at time t7, the accumulator 34 is opened by switching the electromagnetic switching valve 32 to the second connection state, and the hydraulic oil in the accumulator 34 is quickly discharged. Are supplied to the hydraulic actuator 28 and the engine 12 is restarted to start the vehicle promptly. When the idling stop control is thus completed, the determination in Q12 of FIG. 6 is YES, and the accumulated pressure accumulation value is cleared to 0 in Q13.

  In this embodiment, regardless of whether the vehicle is decelerating or not, Q7 to Q11 are executed to update the accumulated pressure amount accumulated value, so that the accumulated pressure state of the accumulator 34 can be estimated with high accuracy without using a hydraulic sensor. This is possible, and the pressure accumulation control for increasing the line pressure PL can be suppressed to the minimum necessary, and an improvement in fuel efficiency can be expected.

  The idling stop control unit 56 that executes the flowchart of FIG. 4 can also determine the pressure accumulation state using the accumulated pressure amount instead of the accumulator pressure Pacc.

  As mentioned above, although the Example of this invention was described in detail based on drawing, these are one Embodiment to the last, This invention is implemented in the aspect which added the various change and improvement based on the knowledge of those skilled in the art. be able to.

  12: Engine 14: Mechanical oil pump 34: Accumulator 50: Electronic control device for hydraulic control 56: Idling stop control unit Pacc: Accumulator pressure (accumulated pressure state) Tis: Stoppable time

Claims (1)

An engine used as a driving force source for traveling;
A mechanical oil pump rotationally driven by the engine;
An accumulator for accumulating pressure connected to the mechanical oil pump;
In an idling stop control device that automatically stops the rotation of the engine under a certain condition and releases the hydraulic pressure by releasing the accumulator when the engine is restarted,
An idling stop control device for a vehicle, characterized in that a stop possible time of the engine is set based on a pressure accumulation state of the accumulator, and the engine is stopped by rotating the stop possible time as an upper limit.

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