JP2006002916A - Vehicular travel control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular travel control device for optimally determining a shift stage or a shift ratio for a shift destination when performing shift-point speed reduction control of a vehicle with the shifting operation of a transmission into the shift stage or the shift ratio for a relatively lower speed. <P>SOLUTION: The vehicular travel control device performs speed reduction control of the vehicle with the shifting operation of the vehicular transmission 10 into a target shift stage or a target shift ratio for a relatively lower speed. The target shift stage or the target shift ratio is determined in accordance with at least one of a vehicle speed and an engine speed with the shift into the target shift stage or the target shift ratio. In this case, the target shift stage or the target shift ratio found in accordance with a parameter corresponding to a vehicle distance to a preceding vehicle or a parameter corresponding to the size of a corner or the gradient of a road is corrected under preset restrictions in accordance with one of the vehicle speed and the engine speed with the shift into the target shift stage or the target shift ratio. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicular travel control apparatus that performs deceleration control of a vehicle by an operation of shifting a transmission to a relatively low speed gear stage or gear ratio.

  Japanese Patent Application Laid-Open No. 2000-318484 (Patent Document 1) discloses a technique for detecting a distance between a preceding vehicle and lowering a shift stage of a transmission and decelerating by an engine brake when the distance is below a certain distance. Has been.

JP 2000-318484 A

  When performing deceleration control of a vehicle by an operation of shifting the transmission to a relatively low speed gear ratio or gear ratio, it is desired that an optimum gear speed or gear ratio is determined as a gear shift destination. . For example, when performing inter-vehicle distance control as an example of shift point control, conventionally, the gear position or gear ratio is determined based only on parameters corresponding to the inter-vehicle distance (including inter-vehicle time, relative vehicle speed, and collision time). However, it is desired that a further optimal shift speed or gear ratio is determined rather than the shift speed or gear ratio determined by the determination method.

  It is an object of the present invention to control vehicle deceleration by an operation of shifting a transmission to a relatively low speed gear ratio or gear ratio, for example, as shift point control such as inter-vehicle distance control, corner control, or uphill / downhill control. The present invention is to provide a vehicular travel control device that can determine an optimum gear position or gear ratio as a gear shift destination.

  A vehicle travel control device of the present invention is a vehicle travel control device that performs deceleration control of the vehicle by an operation of shifting a vehicle transmission to a target gear stage or target gear ratio for a relatively low speed, The target speed or target speed ratio is determined based on at least one of a vehicle speed and an engine speed when the speed is changed to the target speed or target speed ratio.

  The vehicle travel control device of the present invention controls the distance from the preceding vehicle ahead of the vehicle by the operation of shifting the vehicle transmission to a relatively low speed target gear stage or target gear ratio, or the vehicle. A vehicle travel control device that performs travel control on a corner or uphill in front of the vehicle, based on a parameter corresponding to a distance between the preceding vehicle, or a parameter corresponding to a size of the corner or a slope of a road Determining the target gear stage or the target gear ratio, and at least one of a vehicle speed and an engine speed when the speed is changed to the target gear stage or the target gear ratio with respect to the determined target gear stage or the target gear ratio. On the other hand, by performing correction under a predetermined limit, the target shift speed or target speed ratio is determined, and the limit is determined from the determined target shift speed or target speed ratio. The present invention relates to at least one of a magnitude of a change in a gear stage or a gear ratio and a magnitude of a change in deceleration from the deceleration of the obtained target gear stage or target gear ratio. It is said.

  According to the vehicle travel control device of the present invention, when performing deceleration control of a vehicle by an operation of shifting the transmission to a relatively low speed gear stage or gear ratio, an optimum gear stage or The gear ratio can be determined.

  Hereinafter, an embodiment of a vehicle travel control device of the present invention will be described in detail with reference to the drawings.

(First embodiment)
A vehicle travel control apparatus according to a first embodiment will be described with reference to FIGS. 1 to 5.

  In the present embodiment, as an example of shift point control, in response to a driver's intention to decelerate based on inter-vehicle distance information, downshift control of a shift stage or gear ratio of an automatic transmission is performed to perform deceleration control. The present invention relates to a method for determining a gear position or a gear ratio.

  Conventionally, in the control for performing the downshift to the target shift speed based on the inter-vehicle distance information and increasing the engine braking force, the target shift speed is determined by, for example, parameters of the inter-vehicle time and the relative vehicle speed ( (See FIG. 3).

  On the other hand, in the evaluation result using the actual vehicle by the present inventor, the optimum shift speed is different depending on the vehicle speed even at the same relative vehicle speed and the same inter-vehicle time (details are shown in FIGS. 4 and 5). To be described later). That is, in the conventional method for determining the target shift speed, the optimum target shift speed cannot be determined, so that deceleration control that matches the driver's feeling cannot be performed, and as a result, the driver may feel uncomfortable.

  The target shift speed is determined mainly by the magnitude of the engine braking force necessary for deceleration. In that case, as a basic idea, a method of determining the target shift speed using the inter-vehicle time or the relative vehicle speed as a parameter may be used. However, as a result of the experiment by the present inventor, the following points need to be further considered. That knowledge was obtained.

  That is, the driver feels uncomfortable, such as the engine speed after downshifting (at a relatively low speed or gear ratio), a downshift shock at the start of control, and an upshift shock at the return of control. The target shift speed must be determined in consideration of factors that give Here, if the engine speed is too high, engine noise, deterioration of vibration, and acceleration acceleration when the accelerator is depressed become problems. As a result of experiments described later, it has been found that the optimum target shift speed cannot be determined only with parameters corresponding to the inter-vehicle distance such as the inter-vehicle time and the relative vehicle speed, as in the past.

  Therefore, in the present embodiment, in the shift point control for increasing the deceleration (engine braking force) by downshifting the shift stage of the automatic transmission based on the inter-vehicle distance information between the host vehicle and the forward traveling vehicle, the target shift stage In addition to the inter-vehicle time and the relative vehicle speed, which are parameters for determining the engine speed, the engine speed (or the vehicle speed that is a substitute value for the engine speed) is taken into account, and the target gear position is determined. As a result, a gear position suitable for the driver's feeling is selected, and drivability is improved.

  As described in detail below, the configuration of the present embodiment is based on means that can measure or estimate the inter-vehicle distance between the host vehicle and the vehicle ahead, automatic information based on the information on the inter-vehicle distance and the driver's deceleration intention. It is premised on deceleration control means for performing a downshift of a transmission (AT, CVT, AT mounted on a hybrid vehicle) and performing control (shift control) to increase engine braking force.

  In FIG. 2, reference numeral 10 denotes an automatic transmission, and 40 denotes an engine. The automatic transmission 10 is capable of six-speed shifting by controlling the hydraulic pressure by energization / non-energization of the solenoid valves 121a, 121b, and 121c. In FIG. 2, three electromagnetic valves 121a, 121b, and 121c are illustrated, but the number of electromagnetic valves is not limited to three. The solenoid valves 121a, 121b, and 121c are driven by a signal from the control circuit 130.

  The throttle opening sensor 114 detects the opening of the throttle valve 43 disposed in the intake passage 41 of the engine 40. The engine speed sensor 116 detects the speed of the engine 40. The vehicle speed sensor 122 detects the rotation speed of the output shaft 120c of the automatic transmission 10 that is proportional to the vehicle speed. The shift position sensor 123 detects the shift position. The pattern select switch 117 is used when instructing a shift pattern. The acceleration sensor 90 detects vehicle deceleration (deceleration acceleration). The inter-vehicle distance measuring unit 100 includes a sensor such as a laser radar sensor or a millimeter wave radar sensor mounted on the front part of the vehicle, and measures the inter-vehicle distance from the preceding vehicle.

  The road gradient measurement / estimation unit 118 can be provided as a part of the CPU 131. The road gradient measurement / estimation unit 118 can measure or estimate the road gradient based on the acceleration detected by the acceleration sensor 90. Further, the road gradient measuring / estimating unit 118 may store the acceleration on the flat road in the ROM 133 in advance and obtain the road gradient by comparing with the acceleration actually detected by the acceleration sensor 90.

  The navigation system device 95 has a basic function of guiding the host vehicle to a predetermined destination, and includes an arithmetic processing device and information (map, straight road, curve, uphill / downhill, highway) necessary for traveling the vehicle. Etc.), a first information detection device including a geomagnetic sensor, a gyrocompass, and a steering sensor, and a current position of the vehicle by radio navigation. It is for detecting a position, road conditions, etc., and is provided with a second information detection device including a GPS antenna and a GPS receiver.

  The control circuit 130 inputs signals indicating detection results of the throttle opening sensor 114, the engine speed sensor 116, the vehicle speed sensor 122, the shift position sensor 123, and the acceleration sensor 90, and changes the switching state of the pattern select switch 117. A signal indicating the measurement result by the inter-vehicle distance measuring unit 100 is input, and a signal from the navigation system device 95 is input.

  The control circuit 130 is configured by a known microcomputer and includes a CPU 131, a RAM 132, a ROM 133, an input port 134, an output port 135, and a common bus 136. Signals from the sensors 114, 116, 122, 123, and 90, signals from the switch 117, and signals from the navigation system device 95 and the inter-vehicle distance measuring unit 100 are input to the input port 134. . Solenoid valve driving units 138a, 138b, and 138c are connected to the output port 135.

  The ROM 133 stores in advance the operation (control step) shown in the flowchart of FIG. 1, and stores a shift map for shifting the gear stage of the automatic transmission 10 and an operation (not shown) of shift control. ing. The control circuit 130 shifts the automatic transmission 10 based on various input control conditions.

  Next, with reference to FIG. 4 and FIG. 5, a method for determining the target shift speed in the present embodiment will be described. FIGS. 4 and 5 are actual vehicle evaluation results when the accelerator is turned off and deceleration control is started in a state in which the inter-vehicle time is 2.0 to 2.5 seconds, respectively, and the target shift speed is determined to be the third speed. It is a figure which shows the effect area | region and effect degree in the case (FIG. 4) and the case where it determines to the 4th speed (FIG. 5).

4 and 5, the degree of effect is comprehensively determined based on engine braking force, engine noise due to an increase in engine speed after downshift, shift shock, and the like. From the results of FIGS. 4 and 5, it can be said that the optimum gear stage differs depending on the own vehicle speed even if the inter-vehicle time and the relative vehicle speed are the same. This is considered to be caused by the deterioration of the shift shock due to the engine torque characteristics in the high speed region because the engine speed is high and the engine noise becomes large at the third speed in the high vehicle speed region.
From the above, it is necessary to consider the engine speed after downshifting when determining the target gear position.

  The operation of this embodiment will be described with reference to FIGS.

[Step S1]
First, as shown in step S1 of FIG. 1, the control circuit 130 determines whether or not there is a preceding vehicle based on the signal indicating the inter-vehicle distance input from the inter-vehicle distance measuring unit 100, that is, the own vehicle and the preceding vehicle. It is determined whether or not the inter-vehicle distance is less than or equal to a predetermined value set in advance. Here, the vehicle in front where the inter-vehicle distance is equal to or less than a predetermined value may be a target vehicle that is subject to the follow-up control of the host vehicle, or the inter-vehicle distance is temporarily set to a predetermined value or less although not following the follow-up control. It may be.

  As a result of step S1, if it is determined that there is a vehicle ahead, that is, the inter-vehicle distance is equal to or less than a predetermined value, the process proceeds to step S2. On the other hand, if there is no vehicle ahead, that is, if it is not determined that the inter-vehicle distance is equal to or less than the predetermined value, this control flow is returned.

  In the control circuit 130, instead of directly determining whether or not the inter-vehicle distance is equal to or less than a predetermined value, a parameter indicating that the inter-vehicle distance is clogged to the predetermined value or less, such as a collision time (inter-vehicle distance / relative vehicle speed), Whether the inter-vehicle distance is less than or equal to a predetermined value may be determined indirectly based on the inter-vehicle time (inter-vehicle distance / own vehicle speed), a combination thereof, and the like.

[Step S2]
In step S <b> 2, the inter-vehicle distance measuring unit 100 measures the inter-vehicle distance between the host vehicle and the vehicle ahead and outputs a signal indicating the measurement result to the control circuit 130. Step S3 is performed after step S2.

[Step S3]
In step S3, the control circuit 130 determines whether or not there is a need for downshifting (deceleration control). The control circuit 130 determines whether or not the collision time or the inter-vehicle time is equal to or less than a preset value based on the inter-vehicle distance information obtained in step S2, and as a result of the determination, the collision time or the inter-vehicle time Is less than the set value, it is determined that there is a need for downshifting. As a result of the determination in step S3, if it is determined that there is a need for downshifting, the process proceeds to step S4. If it is determined that this is not the case, the present control flow is returned.

[Step S4]
In step S4, the control circuit 130 calculates a target shift stage (shift stage as a downshift destination) by shift control based on the inter-vehicle time and the relative vehicle speed. In step S4, the shift speed is obtained with reference to a target shift speed determination map (FIG. 3) based on the inter-vehicle time and the relative vehicle speed, which is stored in the ROM 133 in advance. As shown in FIG. 3, the target shift speed is obtained based on the relative vehicle speed [km / h] and the inter-vehicle time [sec] between the host vehicle and the preceding vehicle.

  In FIG. 3, for example, when the relative vehicle speed is −40 [km / h] and the inter-vehicle time is 1.0 [sec], the target shift speed is the third speed. As the relationship between the host vehicle and the preceding vehicle approaches a safe relative vehicle speed or inter-vehicle distance, the target shift speed is set as a higher shift speed (so as not to decelerate). That is, the target shift speed is determined as a higher shift speed on the upper right side of the map of FIG. 3 as the distance between the own vehicle and the preceding vehicle is sufficiently secured, and the closer the own vehicle and the preceding vehicle are. The lower shift position on the lower left side of the map is obtained.

  In the above description, the method of calculating the target shift speed using the target shift speed determination map (FIG. 3) has been described. However, instead of the above method, the target shift speed is calculated by the method described below. You can also.

  That is, the control circuit 130 obtains a target deceleration by the automatic transmission 10 (hereinafter referred to as “shift speed target deceleration”), and performs shift control (shift down) of the automatic transmission 10 based on the gear speed target deceleration. A gear stage (target gear stage) to be selected is determined. Hereinafter, the contents of this method will be described by dividing them into (1) and (2).

(1) First, the gear position target deceleration is obtained.
The gear stage target deceleration corresponds to the engine braking force (deceleration acceleration) to be obtained by the shift control of the automatic transmission 10. The gear stage target deceleration is set as a value equal to or less than a target deceleration described later. The following three methods are conceivable as a method for obtaining the speed target deceleration.

A first method for obtaining the speed target deceleration will be described.
First, the target deceleration is obtained from the target deceleration map of FIG. 6, and the gear stage target deceleration is set as a value obtained by multiplying the obtained target deceleration by a coefficient greater than 0 and 1 or less.

  The target deceleration is obtained with reference to a target deceleration map (FIG. 6) stored in advance in the ROM 133. As shown in FIG. 6, the target deceleration is obtained based on the relative vehicle speed [km / h] and the inter-vehicle time [sec] between the host vehicle and the preceding vehicle. Here, the inter-vehicle time is the inter-vehicle distance / own vehicle speed as described above.

  In FIG. 6, for example, when the relative vehicle speed is −40 [km / h] and the inter-vehicle time is 1.0 [sec], the target deceleration is −0.26 (G). The target deceleration is set to a smaller value (so as not to decelerate) as the relationship between the host vehicle and the preceding vehicle approaches a safe relative vehicle speed or inter-vehicle distance. That is, the target deceleration is obtained as a small value on the upper right side of the target deceleration map of FIG. 6 as the distance between the host vehicle and the preceding vehicle is sufficiently secured. The higher the value, the larger the value on the lower left side of the target deceleration map.

  For example, when the target deceleration is −0.26 G, for example, −0.13 G, which is a value obtained by multiplying a coefficient of 0.5, can be set as the shift stage target deceleration.

Next, a second method for obtaining the shift speed target deceleration will be described.
A gear stage target deceleration map (FIG. 7) is registered in the ROM 133 in advance. The speed target deceleration is obtained with reference to the speed target deceleration map of FIG. As shown in FIG. 7, the shift speed target deceleration is obtained based on the relative vehicle speed [km / h] and the inter-vehicle time [sec] between the host vehicle and the preceding vehicle, similarly to the target deceleration of FIG. For example, as in the case of the above example, when the relative vehicle speed is −40 [km / h] and the inter-vehicle time is 1.0 [sec], −0.15G is used as the gear stage target deceleration. Desired. As is clear from FIGS. 6 and 7, when the relative vehicle speed is large and suddenly approaches, when the inter-vehicle time is short, or when the inter-vehicle distance is short, it is necessary to make the inter-vehicle distance appropriate at an early stage. The deceleration needs to be larger. Also, from this, the lower speed stage is selected in the above situation.

Next, a third method for obtaining the speed target deceleration will be described.
First, the engine braking force (deceleration G) when the accelerator of the current gear stage of the automatic transmission 10 before the start of this control is OFF is obtained (hereinafter referred to as deceleration before shifting). Each gear stage deceleration map (FIG. 8) is registered in the ROM 133 in advance. With reference to each gear stage deceleration map in FIG. 8, the pre-shift deceleration is obtained. As shown in FIG. 8, the deceleration before shifting is obtained based on the gear stage and the rotational speed NO of the output shaft 120 c of the automatic transmission 10. For example, when the current gear stage is 5th and the output rotational speed is 1000 [rpm], the deceleration before shifting is -0.04G.

  The deceleration before shifting may be corrected by a value obtained from each gear speed deceleration map in accordance with various situations such as whether the vehicle is operating an air conditioner or whether there is a fuel cut. In addition, a plurality of gear speed deceleration maps are prepared in the ROM 133 for each situation such as whether the vehicle is operating an air conditioner or whether a fuel cut is present, and each gear speed deceleration used according to those situations is prepared. You may switch maps.

  Next, the speed target deceleration is set as a value between the deceleration before shifting and the target deceleration. That is, the gear stage target deceleration is obtained as a value that is greater than the deceleration before shifting and is equal to or less than the target deceleration. An example of the relationship between the speed target deceleration, the pre-shift deceleration, and the target deceleration is shown in FIG.

The speed target deceleration is obtained by the following equation.
Gear stage target deceleration = (Target deceleration−Deceleration before shifting) × Coefficient + Deceleration before shifting In the above equation, the coefficient is a value greater than 0 and 1 or less.

  In the above example, target deceleration = −0.26G, deceleration before shifting = −0.04G, and calculation is performed with the coefficient set to 0.5, the gear stage target deceleration is −0.15G.

  As described above, a coefficient is used in the first and third methods for determining the target gear position deceleration, but the value of the coefficient is not a theoretical value, but can be appropriately set from various conditions. Value. That is, for example, in a sports car, a relatively large deceleration is preferred when decelerating, and therefore the value of the coefficient can be set to a large value. Further, even for the same vehicle, the value of the coefficient can be variably controlled according to the vehicle speed and the gear stage. The vehicle responsiveness to the driver's operation is improved, the so-called sport mode intended for sharp vehicle driving, and the vehicle's responsiveness to the driver's operation is relaxed, so that the vehicle travels with low fuel consumption. In the case of a vehicle in which a mode called an intended so-called luxury mode or economy mode can be selected, when the sport mode is selected, the shift speed target deceleration is set so that a larger shift speed change occurs than in the luxury mode or the economy mode.

(2) Next, based on the shift speed target deceleration obtained in the above (1), a shift speed to be selected for shift control of the automatic transmission 10 is calculated. Vehicle characteristic data indicating the deceleration G for each vehicle speed at each gear stage when the accelerator is OFF as shown in FIG. 10 is registered in advance in the ROM 133.

  As in the above example, assuming that the output rotational speed is 1000 [rpm] and the gear stage target deceleration is −0.15 G, the output rotational speed is 1000 [rpm] in FIG. It can be seen that the gear stage corresponding to the vehicle speed at the time and having the closest deceleration to the gear stage target deceleration of -0.15G is the third speed. Thus, in the case of the above example, in step S4, the target shift speed is calculated to be the third speed.

  Here, the gear stage that is the closest to the gear stage target deceleration is calculated as the target gear stage. However, the target gear stage is a deceleration that is less than (or more than) the gear stage target deceleration. You may select the gear stage which becomes the deceleration closest to the stage target deceleration. Step S5 is executed after step S4 in FIG.

[Step S5]
In step S5, the engine speed after the downshift to the target gear determined in step S4 is calculated by the control circuit 130. If the slip amount of the torque converter (the difference between the engine speed and the turbine speed) is sufficiently small, the engine speed after the downshift can be obtained by the following equation.
Engine speed after downshift = AT output speed × Gear ratio of target gear stage Step S6 is followed by step S6.

[Step S6]
In step S6, the control circuit 130 compares the engine speed calculated in step S5 with a predetermined value set in advance, and determines whether or not the engine speed is larger than the predetermined value. As a result of the determination, if the engine speed is larger than the predetermined value (step S6-Y), the process proceeds to step S7, and if not (step S6-N), the process proceeds to step S8.

[Step S7]
In step S7, the target shift speed is corrected by the control circuit 130. In other words, the gear position (n + 1) that is one gear higher than the target gear (n) calculated in step S4 is set as the target gear. After step S7, the process proceeds to step S8.

[Step S8]
In step S8, the control circuit 130 determines whether or not the accelerator is OFF (idle ON) based on a signal from the throttle opening sensor 114. In step S8, the driver's intention to decelerate is confirmed and used as a start trigger for deceleration control. If it is determined as a result of step S8 that the accelerator is in an OFF state, the process proceeds to step S9. On the other hand, if it is not determined that the accelerator is in the OFF state, this control flow is returned.

[Step S9]
In step S <b> 9, shift control is started by the control circuit 130. That is, shift control is performed to the target shift stage determined in step S4 or step S7. Along with this, the engine braking force increases. Following step S9, the control flow is returned.

  As described above, in the present embodiment, when the target shift speed is calculated based on the inter-vehicle time and the relative vehicle speed (step S4), the engine speed after downshifting to the calculated target shift speed. Is estimated (step S5), and the target gear position is corrected based on the estimation result (step S6, step S7). As a result, the optimum speed, that is, the engine braking force is ensured, and the speed change stage is selected as the target speed change stage with the least discomfort to the driver in terms of prevention of speed change shock, engine noise and acceleration. Therefore, deceleration control that matches the driver's feeling can be realized.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. 11 and 12.
In the second embodiment, only differences from the first embodiment will be described.

  In the first embodiment, the target shift speed is calculated (step S4 in FIG. 1), the engine speed after downshifting to the calculated target shift speed is calculated (step S5), and the engine speed is calculated. The target gear position has been corrected by the value of (Step S6, Step S7). In contrast, in the second embodiment, the target shift speed determination map (FIGS. 11 and 12) based on the inter-vehicle time and the relative vehicle speed is switched based on the vehicle speed of the host vehicle as a substitute value for the engine speed.

  That is, in the second embodiment, a plurality of target shift speed determination maps (FIGS. 11 and 12) based on the inter-vehicle time and the relative vehicle speed are preset in the ROM 133 in accordance with the vehicle speed. The target shift speed determination map of FIG. 11 is used when the vehicle speed of the host vehicle is less than 80 km / h, and the target shift speed determination map of FIG. 12 is used when the vehicle speed of the host vehicle is 80 km / h or more. Is done. For example, when the inter-vehicle time is 1.5 sec and the relative vehicle speed is 15 km / h, when the vehicle speed of the host vehicle is less than 80 km / h, the third speed is set as the target shift stage (FIG. 11). When the vehicle speed of the vehicle is 80 km / h or higher, the fourth speed is set as the target gear position (FIG. 12).

  When the vehicle speed is high (80 km / h or more), the engine speed is high and the engine noise is large at the third speed, and the shift shock due to the engine torque characteristics in the high speed range is expected to deteriorate. Unlike FIG. 11, the fourth speed is selected as the target gear position.

  As described above, in the second embodiment, the target shift stage is determined based on the vehicle speed of the host vehicle in addition to the parameters corresponding to the inter-vehicle distance such as the inter-vehicle time and the relative vehicle speed. In addition to ensuring, it is possible to select an optimal target shift stage including a shift shock, engine noise, and prevention of a peak feeling during acceleration.

  In the second embodiment, unlike the first embodiment, the calculated target shift speed is downshifted to the target shift speed based only on the parameters corresponding to the inter-vehicle distance such as the inter-vehicle time and the relative vehicle speed. Rather than being corrected by the subsequent engine speed, the target gear position is directly determined based on the parameter corresponding to the inter-vehicle distance such as the inter-vehicle time and the relative vehicle speed and the vehicle speed of the host vehicle. As a modification of the second embodiment, the target shift speed obtained using FIG. 11 or FIG. 12 according to the speed change is based on the engine speed after the speed change as in the first embodiment. It is also possible to perform correction.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG.
In the third embodiment, only differences from the first embodiment will be described.

  FIG. 13 is a flowchart obtained by modifying FIG. In FIG. 13, after step S7, the process returns to step S5, and the engine speed after downshifting to the target gear position corrected in step S7 is calculated (step S5), and the engine speed is equal to or less than a predetermined value. If it is (step S6-N), the target gear position is determined, but if it is not less than the predetermined value (step S6-Y), the target gear position (n + 1 stage) is maintained until it becomes the predetermined value or less. Correction (step S7) is repeatedly performed.

  According to the third embodiment, since the downshift is performed with respect to the target shift stage where the engine speed after the downshift is equal to or less than a predetermined value, the shift shock, engine noise, An optimum target shift stage including the point of preventing a feeling of peaking during acceleration can be selected.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIG.
In the fourth embodiment, only differences from the third embodiment will be described.

  FIG. 14 is a flowchart obtained by modifying FIG. In FIG. 14, when the counter value is 3 or more in step S7, the correction of the target shift speed is not performed, so that the number of corrections to the target shift speed (n + 1) is suppressed to 2 at the maximum. (Step S7, Step S9).

  In the third embodiment, the correction of the target deceleration to the (n + 1 stage) (step S7) is repeated until the engine speed after the downshift becomes equal to or less than a predetermined value (step S6-N) (FIG. 13). . As a result of such a control flow, if it is assumed that the engine braking force (deceleration) is not sufficient at the target gear position where the engine speed after the downshift is equal to or less than a predetermined value, The control flow as in the embodiment is effective.

  According to the fourth embodiment, even if the engine speed after the downshift does not become a predetermined value or less, the number of corrections of the target shift stage is 2 at the maximum, so the engine braking force by the target shift stage Is suppressed from being substantially insufficient for the required amount of deceleration.

  In place of the fourth embodiment, the following method is conceivable as a method for suppressing the shortage of the engine braking force. First, in step S4 of FIG. 13, the shift speed target deceleration is obtained by the method described in the first embodiment. Thereafter, after the target deceleration is corrected to (n + 1 stage) in step S7, the deceleration obtained by the corrected target gear stage is obtained, and the gear stage target reduction obtained in step S4 is obtained. Compare with speed. As a result of the comparison, if the difference between the speed target deceleration obtained in step S4 and the deceleration due to the corrected target speed is equal to or less than a predetermined value, the correction of the target speed is valid, and the process goes to step S5. Return. On the other hand, if the difference exceeds a predetermined value, the correction of the target shift speed is invalidated, and the target shift speed before correction is determined as the final target shift speed. According to this method, it is possible to prevent the deceleration (engine braking force) from becoming substantially insufficient after downshifting to the target shift stage. Further, this method can be used in combination with the method using the counter value.

(Fifth embodiment)
Next, with reference to FIG. 15 to FIG. 19, as an example of the shift point control, a description will be given of an optimum target shift stage determination method when shift point control based on the previous corner R is performed.

  FIG. 16 is a chart for explaining the deceleration control of the present embodiment. FIG. 16 shows a control execution boundary line L, a required deceleration 401, a road shape top view, and an accelerator opening 301.

  In a place (time point) 407 corresponding to the symbol A in FIG. 16, as shown by a symbol 301, the accelerator is OFF (the accelerator opening is fully closed), and the brake is OFF (the braking force is not shown). Zero).

[Step S10]
In step S10 of FIG. 15, the control circuit 130 determines whether or not the accelerator is in an OFF state (fully closed) based on a signal from the throttle opening sensor 114. If it is determined as a result of step S10 that the accelerator is in an OFF state, the process proceeds to step S20. When the accelerator is fully closed (step S10-Y), it is determined that the driver intends to decelerate, and the deceleration control of this embodiment is performed. On the other hand, if it is not determined that the accelerator is in the OFF state, this control flow is returned. As described above, in FIG. 16, the accelerator opening 301 is set to zero (fully closed) at the position (time point) A.

[Step S20]
In step S20, the required deceleration is calculated by the control circuit 130. The necessary deceleration is a deceleration required to turn the other corner at a predetermined desired turning G (in order to enter the corner at a desired vehicle speed). In FIG. 16, the necessary deceleration is indicated by reference numeral 401.

  In FIG. 16, the horizontal axis indicates the distance. As shown in the “top view of the road shape”, the other corner 402 exists from the point 403 of D to the point 404 of F. In order to turn the corner 402 at a desired turning G set in advance, it is necessary to decelerate to the target vehicle speed 406 corresponding to the radius (or curvature) R405 of the corner 402 at the entrance 403 of the corner 402. . That is, the target vehicle speed 406 is a value corresponding to R405 of the corner 402.

  In order to decelerate from the vehicle speed at the place 407 of the symbol A where it is determined that the accelerator is fully closed in step S10 to the target vehicle speed 406 required at the entrance 403 of the corner 402, the deceleration as indicated by the necessary deceleration 401 is required. Is needed. The control circuit 130 calculates the required deceleration 401 based on the current vehicle speed input from the vehicle speed sensor 122, the distance from the current position to the entrance 403 of the corner 402 and R405 of the corner 402 input from the navigation system device 95. To do.

  In FIG. 16, a corner (hereinafter referred to as a virtual corner, not shown) whose R is smaller than R405 of the corner 402 is considered. For comparison, it is assumed that the virtual corner has an entrance at the same position as the entrance 403 of the corner 402. At the entrance 403 of the virtual corner, R of the virtual corner is smaller than R405, and therefore it is necessary to decelerate to a vehicle speed 406v lower than the target vehicle speed 406 of the corner 402. From this, the required deceleration of the virtual corner is indicated by reference numeral 401v having a larger gradient than the required deceleration 401, and it is indicated that a larger deceleration is required than the required deceleration 401.

  In Step S20, if it is determined that there is no corner ahead based on the data input from the navigation system device 95 by the control circuit 130, the necessary deceleration is not obtained. Following step S20, step S30 is executed.

[Step S30]
In step S30, the control circuit 130 determines whether or not the present control is necessary based on, for example, the control execution boundary line L. In the determination, in FIG. 16, if it is located above the control execution boundary line L due to the relationship between the current vehicle speed and the distance to the entrance 403 of the corner 402, it is determined that this control is necessary, and the control execution boundary line If it is positioned lower than L, it is determined that this control is unnecessary. As a result of the determination in step S30, if it is determined that this control is necessary, the process proceeds to step S40. If it is determined that this control is not necessary, this control flow is returned.

  The control execution boundary L is based on the relationship between the current vehicle speed and the distance to the entrance 403 of the corner 402, as long as the deceleration exceeding the preset deceleration due to normal braking does not act on the vehicle. , The line corresponding to the range in which the target vehicle speed 406 cannot be reached (the corner 402 cannot be turned in the desired turn G). In other words, when the vehicle is positioned above the control execution boundary line L, in order to reach the target vehicle speed 406 at the entrance 403 of the corner 402, a deceleration exceeding a preset normal braking deceleration is applied to the vehicle. It is necessary to act.

  Therefore, when the vehicle is positioned above the control execution boundary L, deceleration control corresponding to the corner R of the present embodiment is executed (after step S40), and the driver operates the brake by increasing the deceleration. The target vehicle speed 406 can be reached at the entrance 403 of the corner 402 even when the amount is relatively small (even if the foot brake is stepped on only a little).

  FIG. 18 is a diagram for explaining the control execution boundary line L. FIG. In the hatched portion of the figure, the deceleration region calculated based on the target vehicle speed 406 determined from the curvature radius R of the corner 402 of the road in the vehicle traveling direction is shown. The deceleration region is provided at a position on the high vehicle speed side and on the side where the distance from the corner is small, and the control execution boundary line L indicating the boundary of the deceleration region is higher as the curvature radius R of the corner 402 increases. And it is set so that it can be moved to the side approaching the corner 402. When the actual vehicle speed of the vehicle traveling in front of the corner area exceeds the control execution boundary L in FIG. 18, the deceleration control corresponding to the corner R of the present embodiment is executed.

  As the control execution boundary line L of the present embodiment, a control execution boundary line used for shift point control corresponding to a conventional general corner R can be applied as it is. The control execution boundary line L is created by the control circuit 130 based on the data input from the navigation system device 95 and indicating the distance between R405 of the corner 402 and the corner.

  In the present embodiment, in FIG. 16, the time point (location 407) corresponding to the symbol A where the accelerator opening 301 is zero is located above the control execution boundary line L, and therefore it is determined that this control is necessary. (Step S30-Y), the process proceeds to Step S40.

[Step S40]
In step S40, the control circuit 130 obtains a target deceleration by the automatic transmission 10 (hereinafter, shift speed target deceleration), and based on the shift speed target deceleration, shift control (shift down) of the automatic transmission 10 is performed. ) Is calculated. Hereinafter, the content of step S40 will be described by dividing it into (1) and (2).

(1) First, the gear position target deceleration is obtained.
The gear stage target deceleration corresponds to the engine braking force (deceleration acceleration) to be obtained by the shift control of the automatic transmission 10. The gear stage target deceleration is set as a value equal to or less than the required deceleration 401.
The following three methods are conceivable as a method for obtaining the speed target deceleration.

First, a first method for obtaining the speed target deceleration will be described.
The speed target deceleration is set as a value obtained by multiplying the required deceleration 401 obtained in step S20 by a coefficient greater than 0 and equal to or less than 1. For example, when the required deceleration 401 is −0.20 G, for example, −0.10 G, which is a value obtained by multiplying a coefficient of 0.5, can be set as the gear stage target deceleration.

Next, a second method for obtaining the shift speed target deceleration will be described.
First, the engine braking force (deceleration G) when the accelerator of the current gear position of the automatic transmission 10 is OFF is obtained (hereinafter referred to as the current gear speed deceleration). The current gear speed deceleration (deceleration acceleration) is obtained by referring to the respective gear speed deceleration maps shown in FIG. As shown in FIG. 8, the current shift speed deceleration is obtained based on the shift speed and the rotational speed NO of the output shaft 120 c of the automatic transmission 10. For example, when the current shift speed is 5th and the output rotational speed is 1000 [rpm], the current shift speed deceleration is -0.04G.

  Note that the current gear speed deceleration may be corrected by a value obtained from the current gear speed deceleration map according to various situations such as whether the vehicle is operating an air conditioner or whether a fuel cut is present. In addition, a plurality of current speed stage deceleration maps are prepared in the ROM 133 for each situation such as whether the vehicle is operating an air conditioner or whether a fuel cut is present, and the current speed stage deceleration used according to those situations. You may switch maps.

  Next, the shift speed target deceleration is set as a value between the current shift speed deceleration and the required deceleration. That is, the shift speed target deceleration is obtained as a value that is larger than the current shift speed deceleration and is equal to or less than the required deceleration. FIG. 17 shows an example of the relationship between the speed target deceleration, the current speed reduction, and the required deceleration.

The speed target deceleration is obtained by the following equation.
Speed target deceleration = (Necessary deceleration−Current speed deceleration) × Coefficient + Current speed deceleration In the above equation, the coefficient is a value greater than 0 and less than or equal to 1.

  In the above example, the required deceleration = −0.20 G, the current gear speed deceleration = −0.04 G, and when the calculation is performed with the coefficient set to 0.7, the gear speed target deceleration is −0.15 G. .

  As described above, the coefficient is used in the first and second methods for determining the gear stage target deceleration. The value of the coefficient is theoretically the same as the coefficient used in the first embodiment. It is not a value that can be obtained, but an appropriate value that can be set appropriately from various conditions.

(2) Next, based on the shift speed target deceleration obtained in (1) above, the target shift speed for the shift control of the automatic transmission 10 is calculated. The vehicle characteristic data indicating the deceleration G for each vehicle speed at each gear stage when the accelerator is OFF in FIG. 10 is used.

  As in the above example, assuming that the output rotational speed is 1000 [rpm] and the gear stage target deceleration is −0.15 G, the output rotational speed is 1000 [rpm] in FIG. It can be seen that the gear position corresponding to the vehicle speed at the time and the deceleration closest to the gear speed target deceleration of -0.15G is the third speed. Thus, in the case of the above example, in step S40, the target shift speed is calculated to be the third speed.

  The following method can be used as a method for calculating the shift speed that is the closest to the shift speed target deceleration as the target shift speed. The maximum value (maximum deceleration) of deceleration due to the shift of the automatic transmission 10 is obtained by referring to the maximum deceleration map stored in the ROM 133 in advance. In the maximum deceleration map, the maximum deceleration value indicates the type of shift (for example, the combination of the shift stage before the shift and the shift stage after the shift, such as 4th speed → 3rd speed, 3rd speed → 2nd speed). It is determined as a value based on the vehicle speed (output rotation speed). With reference to the maximum deceleration map, a shift stage that is the closest to the shift stage target deceleration is calculated as a target shift stage from the current vehicle speed and the current shift stage.

  In this example, the shift speed closest to the shift speed target deceleration is calculated as the target shift speed. However, the target shift speed is a speed that is equal to or lower than the shift speed target deceleration. You may select the gear stage which becomes the deceleration nearest to the stage target deceleration.

  Further, in step S40, the target shift speed can be calculated by the following method.

In step S40, the downshift determination map shown in FIG. 19 can be used for calculating the target shift speed. In FIG. 19, based on the radius (or curvature) R of the corner 402 and the road gradient θ _R at the location A (step S10-Y) where the accelerator is OFF and the brake is OFF, the downshift destination shift stage in the corner control is shown. Is stipulated.

FIG. 19 shows a downshift having a plurality of types of regions corresponding to driving operations in a two-dimensional coordinate system with a horizontal axis representing the radius of curvature R of the curved road ahead of the vehicle and a vertical axis representing the gradient θ _{R of the} traveling road surface. It is a judgment map. In this downshift determination map, a first downshift area A ₁ , a second downshift area A ₂ , and a non-downshift area A ₃ are provided. The downshift determination map is set so that the engine driving force during uphill driving or downhill can be obtained more than in the case of automatic shift control using a shift diagram used at times other than shift point control. Has been.

The first downshift region A ₁ is a road surface that requires a relatively large climbing driving force (engine braking force when descending) (the curvature radius R is small) and the road surface inclination θ _R is tight (large). Or corresponding to a straight downhill road having a relatively large gradient θ _R requiring a relatively large engine brake, and a point indicating the curvature radius R and the road surface inclination θ _R is in the region A ₁ The shift to the third gear is determined.

In the second downshift region A ₂ , the road curve that requires a moderate uphill driving force (engine braking force when downhill) is moderate (curvature radius R is medium), and the road surface inclination θ _R is also medium. Or a relatively small climbing drive force (engine braking force when descending), the road curve is gentle (the radius of curvature R is relatively large) and the road slope θ _R is also relatively gentle (small). If the point indicating the radius of curvature R and the road surface inclination θ _R is within the area A ₂ , the shift to the fourth gear is determined.

The non-downshift region A ₃ corresponds to a straight uphill road or a gentle downhill road that does not require an increase in engine braking force, and a point indicating the curvature radius R and the road surface inclination θ _R is the area A _3. If it is within, the downshift is not determined regardless of the driving operation state.

  Suppose now that corner R of corner 402 is an intermediate medium corner and location A is a gentle downhill. In this case, the downshift determination map of FIG. 19 shows that the fourth speed is the optimum gear position. In step S40, the optimal shift speed determined in the downshift determination map is compared with the current shift speed to determine whether or not the current shift speed is higher than the optimal shift speed. Is done. As a result of the determination, if the current shift speed is higher than the optimal shift speed, the optimal shift speed is calculated as the target shift speed.

  In this example, if the current gear position at the location A is the fifth speed, the fourth speed is calculated as the target gear position in step S40.

  After step S40, the process proceeds to step S50. Step S50 is the same as step S5 of the first embodiment (FIG. 1). Further, Steps S60 to S90 in FIG. 15 are the same as Steps S6 to S9 in the first embodiment. Therefore, these descriptions are omitted.

  According to the fifth embodiment described above, the target shift speed is calculated based on the required deceleration, or the radius (or curvature) R of the corner and the place where the accelerator is OFF and the brake is OFF (step S10- Y) is performed based on the road gradient at the place (step S40), and the engine speed after downshifting to the calculated target gear position is predicted (step S50), and based on the predicted result. The target gear position is corrected (steps S60 and S70). As a result, it is possible to select a gear position that is optimal, that is, the engine braking force is ensured, and that the driver feels as little discomfort as possible in terms of preventing shift shock, engine noise, and a feeling of acceleration. Thus, deceleration control that matches the driver's feeling can be realized.

  That is, in the fifth embodiment, in the control for downshifting the automatic transmission and increasing the deceleration (engine braking force) based on the size R of the corner, the parameter for determining the target gear position is a parameter for determining the target gear position. In addition to the magnitude R, the engine speed (or the vehicle speed that is a substitute value for the engine speed) is taken into account to determine the target gear position. As a result, a gear position suitable for the driver's feeling is selected, and drivability is improved.

  In the fifth embodiment, the technique of the first embodiment is applied to corner control, but not only the first embodiment but also the second to fourth embodiments. It is possible to apply any of these techniques.

  In the first to fifth embodiments, the shift point control (deceleration control performed by shifting the transmission to a relatively low speed gear ratio or gear ratio based on road conditions or traffic conditions) Although distance control and corner control have been described, similarly, the above technique can be applied to other shift point controls such as uphill / downhill control and intersection control. For example, in the case of uphill / downhill control, the target shift speed is calculated based on the road gradient, and the calculated target speed is calculated based on the engine speed when downshifted to the calculated target shift speed. The gear position can be corrected.

  In the above description, the stepped automatic transmission 10 has been described as an example, but the present invention can also be applied to CVT. In that case, the above-mentioned “gear stage” and “shift stage” may be replaced with “speed ratio”, and “downshift” may be replaced with “adjustment of CVT”. In the above description, the deceleration indicating the amount that the vehicle should decelerate has been described using the deceleration acceleration (G). However, the deceleration can be controlled based on the deceleration torque.

It is a flowchart which shows operation | movement of 1st Embodiment of the vehicle travel control apparatus of this invention. 1 is a schematic configuration diagram of a first embodiment of a vehicle travel control device of the present invention. It is a figure which shows the target gear stage determination map in 1st Embodiment of the vehicle travel control apparatus of this invention. It is a figure for demonstrating the determination method of the target gear stage in 1st Embodiment of the vehicle travel control apparatus of this invention. It is another figure for demonstrating the determination method of the target gear stage in 1st Embodiment of the traveling control apparatus for vehicles of this invention. It is a figure which shows the target deceleration map in 1st Embodiment of the vehicle travel control apparatus of this invention. It is a figure which shows the gear stage target deceleration map in 1st Embodiment of the vehicle travel control apparatus of this invention. It is a figure which shows each gear stage deceleration map in 1st Embodiment of the traveling control apparatus for vehicles of this invention. It is a figure which shows the relationship between the variable speed target deceleration in 1st Embodiment of the traveling control apparatus for vehicles of this invention, deceleration before shifting, and target deceleration. It is a figure which shows the deceleration for every vehicle speed of each gear stage in 1st Embodiment of the vehicle travel control apparatus of this invention. It is a figure which shows the target gear stage determination map in 2nd Embodiment of the vehicle travel control apparatus of this invention. It is a figure which shows the other target gear stage determination map in 2nd Embodiment of the vehicle travel control apparatus of this invention. It is a flowchart which shows operation | movement of 3rd Embodiment of the traveling control apparatus for vehicles of this invention. It is a flowchart which shows operation | movement of 4th Embodiment of the traveling control apparatus for vehicles of this invention. It is a flowchart which shows operation | movement of 5th Embodiment of the vehicle travel control apparatus of this invention. It is a chart for demonstrating the deceleration control of 6th Embodiment of the traveling control apparatus for vehicles of this invention. It is a figure which shows the relationship between the variable speed target deceleration in 6th Embodiment of the traveling control apparatus for vehicles of this invention, the present gear stage deceleration, and required deceleration. It is a figure which shows the control implementation boundary line in 6th Embodiment of the vehicle travel control apparatus of this invention. It is a figure which shows the downshift determination map in 6th Embodiment of the vehicle travel control apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Automatic transmission 40 Engine 90 Acceleration sensor 95 Navigation system apparatus 100 Inter-vehicle distance measurement part 114 Throttle opening sensor 116 Engine speed sensor 118 Road gradient measurement and estimation part 122 Vehicle speed sensor 123 Shift position sensor 130 Control circuit 131 CPU
133 ROM

Claims (2)

A vehicle travel control device that performs deceleration control of the vehicle by an operation of shifting the transmission of the vehicle to a target gear stage or target gear ratio for relatively low speed,
The target speed or target speed ratio is determined based on at least one of a vehicle speed and an engine speed when the speed is changed to the target speed or target speed ratio. Control device. Control of the distance from the preceding vehicle in front of the vehicle, or travel control for a corner or ascending / descending slope in front of the vehicle, by shifting the vehicle transmission to a target gear stage or target gear ratio for relatively low speed. A vehicular travel control device for performing
Based on the parameter corresponding to the inter-vehicle distance from the preceding vehicle, or the parameter corresponding to the size of the corner or the road gradient, the target gear stage or target gear ratio is obtained, and the obtained target gear stage or target The target gear ratio is corrected by performing correction under a predetermined limit based on at least one of the vehicle speed and the target gear position or the engine speed when the gear ratio is changed to the target gear ratio. Stage or target gear ratio is determined,
The limitation includes the magnitude of the change in the shift speed or the gear ratio from the determined target shift speed or target speed ratio, and the change in the deceleration from the deceleration of the determined target shift speed or target speed ratio. The vehicle travel control device according to claim 1, wherein the vehicle travel control device is related to at least one of the points.

Images