JP2010249202A - Vehicle control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform neutral control by a proper road surface gradient of not causing a retreat of a vehicle, in the vehicle for performing the neutral control and hill hold control. <P>SOLUTION: In the device for performing the neutral control and the hill hold control, an ECU determines that a road surface gradient G detected by a G sensor is smaller than an N control permitting gradient (YES in S10), and corrects the N control permitting gradient to the small side (the side of becoming difficult to perform the neutral control) (S40), when a driver performs starting operation for starting the hill hold control (YES in S30), though the neutral control is performed (S30). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for a vehicle including an automatic transmission, and more particularly to control of a vehicle in which neutral control is executed.

  Generally, a vehicle equipped with an automatic transmission is provided with a shift lever operated by a driver, and the control state (shift range) and the gear ratio of the automatic transmission according to the position of the shift lever (shift position). Is changed.

  In such a vehicle, when the shift position is the forward traveling position and the vehicle is stopped, the driving force from the engine is transmitted to the transmission via the torque converter, which is transmitted to the wheels, so-called creep phenomenon. Will occur. The creep phenomenon is very useful under predetermined conditions, such as being able to smoothly start from a stop on an uphill road, and also causes a reduction in fuel consumption.

  For the purpose of suppressing such fuel consumption reduction, even if the shift position is the forward travel position, the automatic transmission is set to the neutral range (power transmission) when the brake pedal is depressed and the vehicle is stopped. There is a vehicle in which control for improving fuel consumption (hereinafter also referred to as “neutral control”) is executed as a neutral state).

  If this neutral control is performed on a steep slope, the vehicle may move backward when returning from the neutral control. Therefore, generally, execution of neutral control is permitted only when the G sensor value for detecting the road surface gradient is below a predetermined threshold value.

  Japanese Patent Laying-Open No. 2004-286146 (Patent Document 1) discloses a technique for correcting a threshold value that permits the start of neutral control. The control device disclosed in Japanese Patent Application Laid-Open No. 2004-286146 includes a G sensor that detects a road surface gradient, a primary pulley rotation number sensor that detects the number of pulses when the vehicle is moving backward when returning from neutral control, and an initial state Stores the relationship between the threshold value for permitting neutral control and the number of pulses, and the relationship between the G sensor value at the start of neutral control and the number of pulses at the time of return from neutral control in the latest state Then, the threshold value is learned based on the number of pulses corresponding to the threshold value based on the relationship between the stored initial states and the stored relationship between the latest states. In this way, it is possible to learn the threshold value that permits the start of neutral control in consideration of the latest vehicle state. Accordingly, the neutral control can be optimally executed to achieve the effect of improving the fuel consumption.

JP 2004-286146 A JP 2007-205452 A JP 2008-157417 A

  By the way, a vehicle having a function of performing hill hold control when the vehicle is stopped is known. The hill hold control is, for example, when the driver performs a predetermined start operation (for example, stepping on the brake pedal) when the vehicle is stopped in order to appropriately prevent the vehicle from retreating when starting on an uphill road. Until the predetermined condition is satisfied, the brake is applied even if the driver does not step on the brake pedal.

  For vehicles equipped with this hill hold control function, for example, when starting on an uphill road, various factors such as vehicle weight, road surface gradient, brake system and engine system response speed, and driver's driving skill are comprehensively considered. When the driver determines that the vehicle may move backward, the driver himself can perform a predetermined start operation to execute the hill hold control. Retreat can be prevented.

  That is, when the driver executes hill hold control when starting on an uphill road, the driver mainly determines that the vehicle may move backward in consideration of various factors. Therefore, when the G sensor value is smaller than the threshold value and execution of neutral control is permitted, but the driver causes the hill hold control to be executed, the G sensor value or the threshold value is not an appropriate value. Probability is high.

  However, Patent Documents 1 to 3 described above do not disclose any relationship between the execution of the hill hold control and the correction of the threshold value that permits the execution of the neutral control.

  The present invention has been made in order to solve the above-described problems, and the object thereof is neutral control with an appropriate road surface gradient that does not cause the vehicle to reverse in a vehicle in which neutral control and hill hold control are executed. It is providing the control apparatus which can perform.

  A control device according to the present invention controls a vehicle equipped with an automatic transmission. In this vehicle, the user of the vehicle performs an operation for starting execution of hill hold control that applies a braking force to the vehicle until a predetermined condition is satisfied even if the user of the vehicle does not step on the brake pedal. Hill hold control is executed in response to the control, and when the condition that the slope of the road surface where the vehicle is stopped is gentler than a threshold value is satisfied, the automatic transmission is controlled to a neutral state. Execution is allowed. The control device determines whether or not the hill hold control is executed during the execution of the neutral control, and if the hill hold control is executed during the execution of the neutral control, the control device makes it difficult to execute the neutral control. And a correction unit for correcting the threshold value.

  ADVANTAGE OF THE INVENTION According to this invention, in the vehicle in which neutral control and hill hold control are performed, neutral control can be performed with the appropriate road surface gradient which does not produce the reverse of a vehicle.

1 is an overall configuration diagram of a vehicle. It is a flowchart which shows the flow of a process of ECU.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a diagram showing an overall configuration of a vehicle equipped with a control device according to an embodiment of the present invention. This vehicle is an FF (Front engine Front drive) vehicle. A vehicle other than FF may be used.

  The vehicle includes an engine 102, an automatic transmission 104, drive shafts 120 and 122, front wheels 124 and 126, a brake booster 136, a master cylinder 106, a brake actuator 108, a brake hydraulic circuit 110, and a brake mechanism. 112 and an ECU (Electronic Control Unit) 100.

  The engine 102 is an internal combustion engine that burns a mixture of fuel and air injected from an injector (not shown) in a combustion chamber of a cylinder. The piston in the cylinder is pushed down by the combustion, and the crankshaft is rotated. A rotating electrical machine or the like may be used instead of the engine 102.

  Automatic transmission 104 includes a torque converter and a planetary gear unit 3000. Planetary gear unit 3000 is provided with a plurality of friction engagement elements such as clutches and brakes.

  The engagement force in each element is controlled by the hydraulic circuit 4000 based on a control signal from the ECU 100. By changing the engagement force in each element, a desired gear stage is formed, and the rotational speed of the crankshaft is changed to a desired rotational speed. The output gear of the automatic transmission 104 is in mesh with the differential gear.

  The automatic transmission 104 is connected to a shift cable having one end coupled to the shift lever 114. When the shift cable operates in conjunction with the operation of the shift lever 114, the shift range of the automatic transmission 104 is set. Are switched. Normally, when the position (shift position) of the shift lever 114 is a D (forward) position, an N (neutral) position, an R (reverse) position, or a P (parking) position, the shift range of the automatic transmission 104 is Controlled to D range, N range, R range, and P range, respectively.

  Drive shafts 120 and 122 are connected to the differential gear by spline fitting or the like. Power is transmitted to the left and right front wheels 124 and 126 via the drive shafts 120 and 122.

  A brake disc 138 is provided at one end of the drive shaft 122 on the front wheel 126 side. The brake disc 138 is provided with a brake mechanism 112. The brake mechanism 112 has a wheel cylinder, and the wheel cylinder is provided so as to sandwich the brake disc 138 via a brake pad (not shown). The brake mechanism 112 is connected to one end of the brake hydraulic circuit 110. When the hydraulic pressure in the brake hydraulic circuit 110 increases, the hydraulic pressure applied to the wheel cylinder increases. As the hydraulic pressure increases, the force with which the wheel cylinder pinches the brake disc 138 through the brake pad increases. When the frictional force generated between the brake pad and the brake disc 138 increases, a braking force that suppresses the rotation of the drive shaft 122 acts on the drive shaft 122. Therefore, when the hydraulic pressure in the brake mechanism 112 increases, a braking force corresponding to the increased hydraulic pressure is generated in the vehicle. The brake mechanism 112 is provided on each of the four wheels of the vehicle, but one is shown as a representative in FIG. In the present embodiment, the brake mechanism 112 has been described as a disc brake, but may be a drum brake, for example.

  Master cylinder 106 is connected to the other end of brake hydraulic circuit 110. The master cylinder 106 is provided with a piston (not shown) inside. Then, when the piston moves in response to an input from the brake booster 136, the hydraulic pressure in the master cylinder 106 increases, and accordingly, the hydraulic pressure in the brake hydraulic circuit 110 increases.

  The brake booster 136 uses the negative pressure on the intake side during operation of the engine 102 to boost the pedaling force input to the brake pedal 132 and transmits it to the master cylinder 106. Note that the structure and operation of the brake booster 136 are well-known techniques and will not be described in detail here.

  The master cylinder 106 and the brake hydraulic circuit 110 are connected via a brake actuator 108. The brake actuator 108 includes a solenoid valve and an electric pump. The brake actuator 108 receives a control signal from the ECU 100, operates the electromagnetic valve and the electric pump, and raises or lowers the hydraulic pressure in the brake hydraulic circuit 110. The brake hydraulic circuit 110 is a liquid passage (pipe) that is connected from the brake actuator 108 to the brake mechanism 112 and is filled with brake fluid.

  A vehicle speed sensor 118, a brake pedal force sensor 130, a hydraulic pressure sensor 128 of the master cylinder 106, and a G sensor 140 are electrically connected to the ECU 100 via a harness or the like.

  The vehicle speed sensor 118 detects the speed of the vehicle from the rotational speed of the drive shaft 120. The position switch 116 detects the position (shift position) of the shift lever 114. The brake pedal force sensor 130 detects a brake pedal force (a force with which the driver steps on the brake pedal 132). Instead of the brake pedal force sensor 130, a sensor for detecting the brake stroke amount (stroke amount of the brake pedal 132) may be provided. The hydraulic pressure sensor 128 detects the hydraulic pressure inside the master cylinder 106 (brake master cylinder pressure P). The G sensor 140 detects the gradient G of the road surface on which the vehicle travels or stops.

  The ECU 100 determines the vehicle based on signals sent from the vehicle speed sensor 118, the position switch 116, the brake pedal force sensor 130, the hydraulic pressure sensor 128, the G sensor 140, etc., a map and a program stored in a ROM (Read Only Memory). Are controlled so as to be in a desired state.

  In the present embodiment, ECU 100, when the driver performs a predetermined start operation (for example, an operation to increase brake pedal 132 more strongly so that the brake pedal force or the brake stroke amount exceeds a predetermined amount) when the vehicle is stopped, After that, even if the driver does not step on the brake pedal 132, the vehicle will continue until a predetermined stop condition (for example, a condition that a predetermined time has elapsed after the start operation or a condition that the driver steps on the accelerator pedal) is satisfied. The hill hold control that keeps the brake hydraulic pressure at the time of stop and keeps the brake effective is executed.

  Therefore, for example, when starting the vehicle on an uphill road, the driver, for example, the total weight of the vehicle including passengers and loads, road surface gradient, variation in response speed and response speed of the brake system and engine system, own driving skill, When it is determined that there is a possibility that the vehicle may move backward while switching from the brake pedal 132 to the accelerator pedal in consideration of various factors, the hill hold is performed by performing the predetermined start operation described above. Control can be started. Since the start of the hill hold control causes the brake to be effective even when the driver switches from the brake pedal 132 to the accelerator pedal, it is possible to appropriately prevent the vehicle from retreating against the driver's intention.

  As described above, the driver performs the hill hold control on the uphill road mainly when the driver determines that there is a possibility that the vehicle may move backward in consideration of various factors comprehensively. Note that the start operation and stop condition of the hill hold control are not limited to those described above.

  Further, when the neutral start condition including the condition that the driver depresses the brake pedal 132 and stops the vehicle when the shift position is the D position is established, the ECU 100 determines the shift range in order to improve fuel efficiency. Is executed in a neutral control (hereinafter also referred to as “N control”) in which N is not the D range but the N range (neutral state). When a predetermined N control return condition including a condition that the driver has stopped pressing the brake pedal 132 is satisfied, the ECU 100 sets the shift range to the D range so that the N control is stopped and returned from the N control. To do.

  While the N control is being executed, the driver is stepping on the brake pedal 132, so there is little fear of the vehicle retreating. However, when the brake pedal 132 is released and the N control is stopped, the N control is performed against a decrease in brake hydraulic pressure. If the return from the vehicle is delayed, the vehicle is in a neutral state when the brakes are not effective. Therefore, on a steep uphill road, the vehicle may retreat against the driver's intention.

  In order to prevent this reverse, ECU 100 determines whether or not road surface gradient G detected by G sensor 140 is gentler than a predetermined N control permission gradient, and road surface gradient G is N control permission gradient. Only when it is determined to be more lenient, execution of N control is permitted.

  By the way, the factors that cause the vehicle to retreat upon returning to the N control include, in addition to the road surface gradient, a decrease in the detection accuracy of the G sensor 140 due to aging, the total weight of the vehicle, variations in the response speed and response speed of the brake system, There are various skills. It is difficult to preset the N control permission gradient in consideration of all these factors.

  However, when the road surface gradient G is determined to be gentler than the N control permission gradient and the N control is executed, the driver causes the hill hold control to be executed. Therefore, it is highly likely that the road surface gradient G or the N control permission gradient is not an appropriate value.

  In addition, even in the case of having a function of changing the N control return method in order to avoid a shock at the time of N control return from hill hold control, if the brake system variation is large, the shock should always be avoided. May not be possible.

  Therefore, the ECU 100 according to the present embodiment determines that there is a possibility that the vehicle may move backward when returning to the N control when the driver executes the hill hold control during the execution of the N control. The gradient is corrected to the side where it becomes difficult to execute the N control.

  FIG. 2 is a flowchart showing a flow of processing performed by ECU 100 according to the present embodiment. This flowchart is executed in a predetermined cycle when the driver depresses the brake pedal 132 and stops the vehicle when the shift position is the D position. Each step in the flowchart is realized by executing a program stored in advance in ECU 100. Alternatively, for some steps, it is also possible to construct dedicated hardware (electronic circuit) and realize processing.

  As shown in FIG. 2, in step (hereinafter, step is abbreviated as “S”) 10, ECU 100 determines whether or not road gradient G detected by G sensor 140 is smaller (gradual) than the N control permission gradient. Determine whether. Note that the N control permission gradient is stored in advance in a storage unit inside the ECU 100. The initial value of the N control permission gradient is set in advance by experiments or the like so that the vehicle does not move backward when the N control is restored in consideration of the tolerance of the G sensor 140. If a positive determination is made in this process (YES in S10), the process proceeds to S20. Otherwise (NO in S10), this process ends.

  In S20, ECU 100 executes the above-described N control. That is, ECU 100 transmits a control signal for controlling automatic transmission 104 to the neutral state to hydraulic circuit 4000.

  In S30, ECU 100 determines whether or not the driver has executed the hill hold control described above. When the driver performs a start operation for starting the hill hold control (for example, when the driver performs an operation of pressing the brake pedal 132 more strongly so that the brake pedal force exceeds a predetermined amount), the ECU 100 It is determined that the hill hold control is executed. If a positive determination is made in this process (YES in S30), the process proceeds to S40. Otherwise (NO in S30), this process ends.

  In S40, ECU 100 corrects the N control permission gradient to a smaller side (a side on which N control is difficult to be executed). Specifically, ECU 100 sets the value obtained by subtracting a predetermined correction value from the current N control permission gradient as the corrected N control permission gradient. The corrected N control permission gradient is stored in the storage unit inside the ECU 100 and is used for the determination in S10 of the next cycle.

  As described above, ECU 100 according to the present embodiment determines that road surface gradient G detected by G sensor 140 is smaller than the N control permission gradient (YES in S10), and executes N control (S20). However, if the driver executes the hill hold control (YES in S30), for example, the road surface gradient G detected by the G sensor 140 due to deterioration over time is smaller than the actual gradient (N control is permitted). It is determined that there is a possibility of offset to the easy side), and the N control permission gradient is corrected to a small side (side where it is difficult to permit N control). As a result, when determining whether or not to start N control in the next cycle and thereafter, the N control permission gradient is a value that takes into account the offset amount of the road surface gradient G, so that the vehicle does not reverse unintentionally. N control can be executed with a smooth road surface gradient.

  As a result of correcting the N control permission gradient, when the road surface gradient G becomes larger than the N control permission gradient during the execution of the N control, the execution of the N control may be stopped.

  In the present embodiment, the case where the N control permission gradient is corrected to the side where it is difficult to execute the N control has been described. However, the road surface gradient G detected by the G sensor 140 is not N but the N control permission gradient. You may make it correct | amend to the side which becomes difficult to perform control.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  100 ECU, 102 Engine, 104 Automatic transmission, 106 Master cylinder, 108 Brake actuator, 110 Brake hydraulic circuit, 112 Brake mechanism, 114 Shift lever, 116 Position switch, 118 Vehicle speed sensor, 120, 122 Drive shaft, 124, 126 Front wheel 128 hydraulic pressure sensor, 130 brake pedal force sensor, 132 brake pedal, 136 brake booster, 138 brake disc, 140 G sensor, 3000 planetary gear unit, 4000 hydraulic circuit.

Claims (1)

A vehicle control apparatus including an automatic transmission, wherein the vehicle has a hill hold control that applies a braking force to the vehicle until a predetermined condition is satisfied even if a user of the vehicle does not step on a brake pedal. The hill hold control is executed in response to an operation for starting execution of the vehicle being performed by the user of the vehicle, and the slope of the road surface on which the vehicle is stopped is gentler than the threshold value. When the condition is satisfied, the execution of neutral control for controlling the automatic transmission to a neutral state is permitted,
The control device includes:
A determination unit that determines whether or not the hill hold control is executed during the execution of the neutral control;
A control device for a vehicle, comprising: a correction unit that corrects the threshold value on a side where the neutral control is difficult to be executed when the hill hold control is executed during the neutral control.

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