JP2003329123A - Vehicle control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem such as busy shift in executing low-speed cruise control and thereby to improve driveability. <P>SOLUTION: In an ECU 10, a first CPU 11 executes low-speed cruise control for keeping the inter-vehicle distance between one's own vehicle and a preceding vehicle by keeping a vehicle speed at a target value in a predetermined low- speed region. In addition to a normal speed change map, an auxiliary upshift map formed by widening the range of a speed change line for an upshift as compared with the normal speed change map with respect to a parameter of the vehicle speed is prepared. In executing the low-speed cruise control, when the own vehicle is not in the targeted speed nor in the targeted inter-vehicle distance and in an acceleration state, or when the inter-vehicle distance to the preceding vehicle tend to increase, the speed change control using the auxiliary upshift map is executed, and returned to the speed change control by the normal speed change map after the targeted vehicular speed and inter-vehicle distance are established. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle control device for executing a low speed cruise control for maintaining a vehicle speed at a target speed in a low speed region and maintaining a constant inter-vehicle distance between a host vehicle and a preceding vehicle.

[0002]

2. Description of the Related Art Cruise control (constant speed traveling control) for keeping a vehicle speed constant is known as a vehicle traveling control, and in recent years, radar cruise control using a laser radar sensor has been put into practical use. In this radar cruise control, the inter-vehicle distance between the host vehicle and the preceding vehicle is measured by a laser radar sensor, and the host vehicle is made to travel following the preceding vehicle. Further, so-called low-speed cruise control has been proposed, in which cruise control is performed only within a predetermined low-speed region (for example, 30 km / h or less). For example, when a traffic jam occurs, the vehicle starts and stops following the preceding vehicle. Is to be done.

On the other hand, during such cruise control, the transmission is automatically changed as appropriate in accordance with the vehicle traveling state at each time. In this automatic shift, generally, a shift map having throttle opening and vehicle speed as parameters is used, and an upshift or a downshift is performed by crossing a shift line on the map. However, when the low speed cruise control is performed in the low speed region as described above, the following problems occur when the vehicle starts following the preceding vehicle.

That is, when the preceding vehicle starts in a state where the low speed cruise control is executed and the host vehicle starts following it, the throttle opening degree increases once and then decreases to maintain the vehicle speed as the vehicle speed converges. Returned to the side. In this case, as the throttle opening is returned, an upshift occurs in a plurality of times, resulting in a busy shift. Therefore, there arises a problem that drivability is deteriorated.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to solve the problems such as busy shift during low speed cruise control. It is an object of the present invention to provide a vehicle control device capable of improving drivability.

[0006]

A vehicle control device of the present invention comprises a gear shift control means and a low speed cruise control means, and the gear shift control means implements gear shift control of a transmission mounted on a vehicle. Also, the low speed cruise control means
The vehicle speed is maintained at the target speed in a predetermined low speed region, and the inter-vehicle distance between the host vehicle and the preceding vehicle is maintained constant. Especially claim 1
In the invention described in, a normal shift map that defines a plurality of shift lines with throttle opening and vehicle speed as parameters,
And an auxiliary upshift map in which the upshift gearshift line has a wider range for the vehicle speed parameter than the normal gearshift map. When the low-speed cruise control is performed by the low-speed cruise control means, when the host vehicle is in an accelerating state without a target vehicle speed and inter-vehicle distance, or when the inter-vehicle distance with the preceding vehicle tends to be expanded, The shift control using the auxiliary upshift map is performed, and after returning to the target vehicle speed and the inter-vehicle distance, the shift control is returned to the normal shift map.

In short, when the preceding vehicle starts when the low speed cruise control is executed and the host vehicle follows it, the throttle opening is once increased and then returned to the decreasing side after the vehicle speed converges as described above. Therefore, if the normal shift map is used as it is, an upshift occurs in a plurality of times as the throttle opening decreases, resulting in a busy shift.
On the other hand, in the present invention, even if the throttle opening similarly increases and then decreases, the upshift is not repeated many times by using the auxiliary upshift map having the wide range of the vehicle speed parameter. That is, when the vehicle speed is almost constant and only the throttle opening is reduced, the upshift does not excessively occur. Then, after the target vehicle speed and the inter-vehicle distance are converged, the shift control is returned to the normal shift map, and the shift position (gear stage) is controlled to match the running state at that time. From the above, it is possible to solve problems such as busy shift when the low speed cruise control is executed, and to improve drivability.

According to the second aspect of the present invention, when the own vehicle accelerates and then reaches the target vehicle speed and inter-vehicle distance, if the transmission is in the driving state, the auxiliary upshift map of the auxiliary upshift map is set until the inertial state is reached. Continue to use. In this case, the transmission is inertial (non-driven)
Since the normal speed change map is restored after waiting until, the map switching in the transitional state is prevented, and more stable vehicle traveling becomes possible.

Incidentally, whether the transmission is in the driving state or the inertial state (non-driving state) can be known from the input and output speeds of the transmission. That is, in the drive state of the transmission, the relationship of input speed> output speed is satisfied, and in the inertia state, the relationship of input speed <output speed is reversed.

According to the third aspect of the invention, there is further provided an auxiliary downshift map in which the shift line for downshifting is set to a higher speed side than the normal shift map. When the low-speed cruise control is performed by the low-speed cruise control means, when the host vehicle is in a decelerating state and the inter-vehicle distance with the preceding vehicle tends to be shortened because the target vehicle speed and inter-vehicle distance are not present, Shift control is performed using the auxiliary downshift map. In this case, the auxiliary downshift map enables early downshifting. Therefore, the effect (handiness) of engine braking is enhanced.
Further, when the downshift is performed immediately before the vehicle is stopped and the engine output is small, the shift shock is large, but such an inconvenience is eliminated.

According to another aspect of the present invention, when the transmission decelerates when the host vehicle decelerates and then reaches the target vehicle speed and inter-vehicle distance, the auxiliary downshift map is used until the inertial state is reached. continue. Also in this case, as in the case of the above-mentioned claim 2, since the transmission is returned to the normal shift map after waiting until the transmission is in the inertia state (non-driving state), map switching in the transient state is prevented and the stability is further stabilized. The vehicle can run.

As described in claim 5, the low-speed cruise control means measures the inter-vehicle distance between the own vehicle and the preceding vehicle by a laser radar sensor installed in the front of the vehicle, and implements follow-up control for the preceding vehicle. Is.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. In this embodiment,
An in-vehicle ECU as a vehicle control device is supposed to perform low-speed cruise control, and in particular, a laser radar sensor installed in the front of the vehicle measures the inter-vehicle distance between the own vehicle and the preceding vehicle, and implements follow-up control for the preceding vehicle.

FIG. 1 is a block diagram showing a schematic structure of the vehicle-mounted ECU. In FIG. 1, the ECU 10 is the first CP.
A U11, a second CPU 12, an integrated IC 13, an input interface (input I / F) 14 and an output interface (output I / F) 15 are provided. First CPU 11 and second C
The PU 12 exchanges various data and the like via a known communication means such as DMA. The first CPU 11 mainly has a function of performing fuel injection control, ignition control, electronic throttle control, and cruise control, and the second CPU 12 mainly has a function of performing transmission shift control. In the present embodiment, the first CPU 11 corresponds to "low speed cruise control means" and the second CPU 12 corresponds to "shift control means". However, the distribution of these control functions is arbitrary and is not limited at all.

Through the input I / F 14, the ECU 10 inputs an engine speed signal, an intake air amount signal, a throttle opening signal, an accelerator opening signal, a transmission shift position signal, a transmission output shaft speed signal, and a laser radar sensor signal. , A cruise SW signal and the like are input. Then, the first CPU 11 outputs a control signal to the injector, the igniter, and the throttle motor based on the above various signals to control the driving of these. Further, the second CPU 12 outputs a control signal to the shift solenoid of the transmission based on the above various signals to control the shift change (gear shift) of the transmission.

In addition, the first CPU 11 carries out the low speed cruise control so that the low speed region (for example, 30 k
m / h or less), the vehicle speed is kept at the target speed and the inter-vehicle distance between the host vehicle and the preceding vehicle is kept constant.

Further, in the present embodiment, as the map showing the shift characteristic, the normal shift map that is the basis of the shift characteristic and the shift line for upshifting is wider than the normal shift map for the vehicle speed parameter. An upshift map (auxiliary upshift map) and a downshift map (auxiliary upshift map) in which a shift line for downshift is set to a higher speed side than a normal shift map are prepared in advance. Then, in the low speed cruise control, they are selectively used according to the vehicle operating state. The shift characteristics of each are shown in FIG.

FIG. 2 (a) shows a normal shift map, in which the shift line for upshift and the downshift are used with the throttle opening and the output shaft speed (corresponding to the vehicle speed) at each time as parameters. The shift line and are set. In FIG. 2A, the solid line indicates an upshift (1st speed → 2nd speed, 2nd speed → 3).
The shift lines for the third speed, the third speed and the fourth speed are shown, and the dotted lines show the shift lines for the downshift (the second speed, the first speed, the third speed, the second speed, the fourth speed, and the third speed). However, FIG. 2 (a) shows only the characteristics in the low speed region, and the low speed region is 0 to 100 in terms of output shaft rotation speed.
It is a region of 0 rpm (corresponding to 0 to 30 km / h at vehicle speed).

The upshift map shown in FIG. 2 (b) is obtained by changing the upshift characteristic of the normal shift map (the characteristic of the dotted line in the figure) as shown by the solid line in the figure. Further, in the downshift map shown in FIG. 2C, the downshift characteristic of the normal shift map (the characteristic of the dotted line in the figure) is changed as shown by the solid line in the figure.

FIG. 3 is a flowchart showing a shift characteristic switching process for selectively using the shift characteristic.
This process is executed by the second CPU 12 in a predetermined time cycle. In this process, a shift map for shift control is appropriately selected according to the vehicle operating state at each time.

First, at step 101, it is judged if the low speed cruise control is being executed. At this time, if the cruise SW is ON and the accelerator pedal is not depressed, it is determined that the low speed cruise control is being executed. Also, in step 102,
It is determined whether the vehicle speed is not zero. When the low speed cruise control is not being executed, or when the vehicle speed is 0, the process directly proceeds to step 107, and the normal shift map is selected.
As a result, the shift line for each case is determined using the normal shift map shown in FIG. 2A, and a shift change is performed.

When the low speed cruise control is being executed and the vehicle speed is not 0, it is determined in step 103 whether or not the vehicle speed has reached the set vehicle speed (target vehicle speed), and in step 104, the distance between the vehicle and the preceding vehicle. It is determined whether or not the distance has reached the set distance. These steps 103 and 104 are for determining that the vehicle is in a transitional state with respect to the target state (vehicle speed, inter-vehicle distance) during execution of the low speed cruise.
If it is O, the process proceeds to step 108.

Steps 105 and 106 determine whether the transmission is in a driving state or in a coasting state (non-driving state) immediately after accelerating or decelerating the vehicle, and the transmission coasts after acceleration or deceleration. When the state is reached, both steps 105 and 106 are NO (note that both steps 105 and 106 are NO if neither immediately after acceleration nor immediately after deceleration). Therefore, the routine proceeds to step 107, where the normal shift map is selected. Whether the transmission is in the driving state or the inertial state is determined from the input shaft rotation speed and the output shaft rotation speed of the transmission.

Further, when the routine proceeds to step 108, it is judged whether the inter-vehicle distance tends to shorten or expand. For example, when the preceding vehicle accelerates, the inter-vehicle distance is expanded, and when the preceding vehicle decelerates, the inter-vehicle distance is shortened. It should be noted that this determination is performed by the laser radar sensor signal.

If the inter-vehicle distance tends to expand, the routine proceeds to step 109, where the upshift map for low speed cruise control (the map of FIG. 2B) is selected. If the inter-vehicle distance tends to be shortened, the routine proceeds to step 110, where it is determined whether or not the vehicle is in the idle state (throttle opening = 0). If it is in the idle state, the routine proceeds to step 111, and the downshift map for low speed cruise control (the map of FIG. 2 (c)) is selected. If it is not in the idle state, the routine proceeds to step 107, where a normal shift map is selected.

If the host vehicle accelerates or decelerates following the acceleration or deceleration of the preceding vehicle, the steps 109 or 11 are temporarily executed.
The shift map can be switched with 1. In this case, even if the vehicle speed and the inter-vehicle distance converge to the target state, the transmission remains in the driving state immediately after that (step 105 or 10).
If any of 6 is YES), the shift control is continued as it is. Then, after the transmission is in the inertia state, the shift map is returned to the normal one.

Next, the shift operation by the above process will be described more specifically with reference to the time chart of FIG. In the figure, the upshift map = ON represents a period in which the upshift map of FIG. 2B is used, and the downshift map = ON similarly uses the downshift map of FIG. 2C. It shall represent the period.

Now, in FIG. 4, the cruise SW is turned on in advance.
The vehicle is started at timing t1 with the start of the preceding vehicle. After the timing t1, the throttle opening shifts to the open side and the vehicle speed changes to the target vehicle speed (for example, 30
increase with respect to km / h). At this timing t1, the vehicle speed becomes> 0, and the vehicle speed and the inter-vehicle distance are not the target, and the inter-vehicle distance tends to expand. Therefore, the shift map is switched to the upshift map.

Here, FIG. 5 shows the maps of (b) and (c) of FIG. 2 as (a) and (b), respectively, in which the switching of the gear stage is illustrated.
As shown in (a) of FIG. 5, during the period from t1 to t2 of FIG. 4, as the throttle opening increases, the shift point A1 on the upshift map (solid line in the figure) is upshifted from the first speed to the second speed. To be done.

After that, when the vehicle speed reaches the target vehicle speed at timing t2 in FIG. 4, the throttle opening is returned to the closing side in order to maintain the vehicle speed. At this timing t2, both the vehicle speed and the inter-vehicle distance are in the target state, but since the transmission is in the driving state, the shift control by the upshift map is continued.

Further, at the timing t3, the throttle opening converges to a predetermined opening that allows traveling at the target vehicle speed, and the transmission changes to coasting. As a result, the shift map is returned from the upshift map to the normal shift map. At that time, the gear stage is upshifted from second gear to fourth gear at once. In FIG. 5A, the gear is directly upshifted to the fourth speed at point A2 on the normal shift map (dotted line).

On the other hand, at timing t4, the preceding vehicle starts decelerating. Then, the throttle opening decreases, and the timing t5 when the throttle opening becomes 0 (idle state)
Then, the shift map is switched to the downshift map.
In this case, as shown in FIG. 5B, when the vehicle speed decreases, the shift point B1 on the downshift map (solid line in the figure) is 4
Downshift is performed from the third speed to the third speed, the third speed to the second speed at the shift point B2, and the second speed to the first speed at the shift point B3.

Thereafter, when the vehicle speed becomes 0 at timing t6, the shift map is returned from the downshift map to the normal shift map. During deceleration indicated by t4 to t6, the downshift is performed early, and the engine brake is effectively used.

Incidentally, when the normal shift map is used throughout the entire period of FIG. 4, as shown by the dotted line before the timing t3, the upshifts of the second speed → the third speed and the third speed → the fourth speed are performed, and the busy shift is performed. Becomes Further, as shown by the dotted line after the timing t4, the downshift is delayed and the engine braking becomes less effective.

When there is an interruption from another lane immediately before the host vehicle while the vehicle is accelerating or traveling at the target speed, the shift map is switched to the downshift map at that time. In this case, sudden deceleration is necessary to maintain the target inter-vehicle distance, but at that time,
Proper deceleration can be achieved by early downshifting.

Next, the cruise SW is turned off during the normal running.
N and the low speed cruise control is started,
This will be described with reference to the time chart of FIG. In FIG. 6, the cruise SW is turned on at the timing t11 during normal traveling,
Accordingly, the throttle opening is reduced to reduce the vehicle speed. Then, the timing t1 when the throttle opening becomes 0
At 2, the shift map is switched to the downshift map. After that, when the vehicle speed reaches the target vehicle speed at timing t13, the throttle opening is returned to the open side to maintain the vehicle speed.

Further, at timing t14, the throttle opening converges to a predetermined opening that allows the vehicle to travel at the target vehicle speed, and the transmission changes to coasting. As a result, the shift map is returned from the downshift map to the normal shift map.

According to the present embodiment described in detail above, it is possible to solve the problem such as busy shift when the low speed cruise control is carried out, and to improve the drivability. In addition, since an early downshift is possible during deceleration, the efficiency of engine braking is enhanced.
By using the engine brake together, the load of brake control during low speed cruise control can be reduced. Further, when the downshift is performed immediately before the vehicle is stopped and the engine output is small, the shift shock is great, but such an inconvenience is also eliminated.

Further, when the upshift map or the downshift map is used during the low speed cruise control, it is decided to wait until the transmission is in the inertia state and to return to the normal shift map, so that the map switching in the transient state is prevented. As a result, more stable vehicle travel becomes possible.

In the above embodiment, the auxiliary upshift map and the auxiliary downshift map are used when the low speed cruise control is executed, but at least only the auxiliary upshift map is used to prevent the busy shift after the vehicle speed converges. It may be configured to.

Further, although the auxiliary upshift map or the auxiliary downshift map is continuously used until the transmission is in the inertia state after the own vehicle is accelerated or decelerated,
This configuration may be changed so that the normal shift map is immediately returned when the vehicle speed and the inter-vehicle distance reach the target state.

In the processing shown in FIG. 3, the auxiliary downshift map is selected on the condition that the engine is in the idle state (throttle opening = 0) (steps 110, 11).
1) It is also possible to delete the condition of being in the idle state.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of an in-vehicle ECU according to an embodiment of the invention.

FIG. 2 is a diagram showing a shift map of a transmission.

FIG. 3 is a flowchart showing a shift characteristic switching process when a low speed cruise is executed.

FIG. 4 is a time chart showing an operation during low speed cruise control.

FIG. 5 is a diagram showing a transmission shift map.

FIG. 6 is a time chart showing an operation during low speed cruise control.

[Explanation of symbols]

10 ... ECU, 11 ... 1st CPU, 12 ... 2nd CPU.

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Claims (5)

[Claims] 1. A shift control means for performing shift control of a transmission mounted on a vehicle, and for keeping a vehicle speed at a target speed in a predetermined low speed region and keeping a vehicle-to-vehicle distance constant. In the vehicle control device including the low speed cruise control means, the normal shift map that defines a plurality of shift lines with the throttle opening and the vehicle speed as parameters, and the shift line for upshifting than the normal shift map. And an auxiliary upshift map with a wide range of vehicle speed parameters, and when the low-speed cruise control is performed by the low-speed cruise control means when the host vehicle is in an accelerating state or ahead of the target vehicle speed and inter-vehicle distance. When the inter-vehicle distance with the vehicle tends to be expanded, the shift control using the auxiliary upshift map is performed and set as a target. A vehicle control device characterized by returning to normal shift control based on a shift map after the vehicle speed and the inter-vehicle distance are converged. 2. The auxiliary upshift map is continued to be used until the inertial state is reached when the transmission is in a driving state when the host vehicle accelerates and then reaches a target vehicle speed and a following distance. Vehicle control device. 3. A target vehicle speed when the low speed cruise control is executed by the low speed cruise control means, further comprising an auxiliary downshift map in which a shift line for downshifting is set to a higher speed side than the normal speed change map. The shift control using the auxiliary downshift map is performed when the host vehicle is in a decelerating state and the inter-vehicle distance with the preceding vehicle tends to be shortened because the inter-vehicle distance is not present.
The vehicle control device described. 4. The auxiliary downshift map is continued to be used until the inertial state is reached when the transmission is in a driving state when the own vehicle decelerates and then reaches a target vehicle speed and a following distance. Vehicle control device. 5. The low-speed cruise control means measures the inter-vehicle distance between the own vehicle and the preceding vehicle by means of a laser radar sensor installed on the front surface of the vehicle, and carries out follow-up control for the preceding vehicle. The vehicle control device according to any one of 1.