JPH02189236A - Car speed controller - Google Patents

Abstract

PURPOSE:To realize constant-speed running on a rough road safely by reducing a car speed when a slip factor comes off the specified slip factor range during the constant-speed running, while decreasing a target car speed of the constant- speed running to some extent, and having it automatically compensated to speed in accord with a road surface. CONSTITUTION:At time of constant-speed running control, each rotational speed of front wheels 27, 28 is calculated on the basis of each output of wheel speed sensors 29, 30 at a throttle control unit 24, and the mean value of these speeds is operated, thereby finding a vehicle speed, and opening of a throttle valve 5 is controlled so as to cause this vehicle speed to become the target ce speed set by a speed setter. In addition, each wheel speed of rear wheels 31, 32 is found out on the basis of each output of wheel speed sensors 49, 50, and a slip factor is calculated from the said vehicle speed and wheel speed. When this slip factor has come off the specified slip factor range, the throttle valve 5 is rotated in the closing direction and a car speed is reduced, while a target car speed of the constant-speed running is decreased to some extent, thus it is automatically compensated to speed in accord with a road surface.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a vehicle speed control device.

[Prior Art] Conventionally, in order to facilitate long-duration driving at a constant speed on expressways, expressways, etc., passenger cars have been equipped with a
There is a constant speed traveling device disclosed in Japanese Patent No. 32827. This constant speed running device is designed to improve vehicle stability on rough roads, i.e., roads with a small or uneven friction coefficient, by increasing the slip rate by slipping on the drive wheels during constant speed driving. When the slip ratio falls outside of a predetermined slip ratio range, constant speed running is canceled and the throttle valve is operated in the fully open direction.

[Problems to be Solved by the Invention] However, in the above-mentioned constant-speed traveling device, when constant-speed traveling is canceled due to occurrence of slip, the throttle valve is operated in the fully closed direction. This can lead to slips, which poses a safety problem.

For this reason, it is desirable to continue running at a constant speed even when a slip occurs. However, if the vehicle continues to drive at a constant speed at the original speed after the drive wheels have stopped slipping, there is a high possibility that slipping will occur again. In other words, for example, if we consider an actual road surface, slipping of the drive wheels occurs while driving at a constant speed on a snowy road, and even if the slipping can be suppressed by temporarily lowering the target vehicle speed, once the slipping subsides, the original speed will be restored. The vehicle will be driven at the target vehicle speed, and as long as the vehicle is traveling on a slippery road surface (snowy road), it will slip again.

This invention has been made to solve the above-mentioned problems, and its purpose is to adjust the slip ratio so that when the slip ratio deviates from a predetermined slip ratio range while driving at a constant speed, the slip ratio falls within the slip ratio range. Vehicle speed control that reduces the vehicle speed and slightly decreases the target vehicle speed for constant speed driving, automatically adjusting to a new target vehicle speed that matches the road surface, making it possible to safely achieve constant speed driving even on rough roads. The goal is to provide equipment.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a torque adjusting means for adjusting the torque applied to the driving wheels of a vehicle, a vehicle speed detecting means for detecting the traveling speed of the vehicle, and the vehicle speed detecting means. constant speed driving control means for controlling the torque adjusting means to perform constant speed driving so that the speed of the vehicle becomes a desired target vehicle speed based on the detection result; and driving wheel speed for detecting the speed of the driving wheels. a detection means, a slip ratio calculation means for calculating a slip ratio based on the detection results of the vehicle speed detection means and the drive wheel speed detection means, and a slip ratio calculated by the slip ratio calculation means that is outside a predetermined slip ratio range. When the slip rate reducing means for controlling the torque adjusting means to reduce the torque applied to the drive wheels and the constant speed running control means are in operation, the slip rate detected by the slip rate calculating means is The gist of the vehicle speed control device is to provide a vehicle speed control device including target vehicle speed changing means for slightly reducing the target vehicle speed during constant speed driving when the slip ratio falls outside of a predetermined slip ratio range.

Further, it is preferable that the target vehicle speed changing means sets the speed reduction amount according to the slip ratio calculated by the slip ratio calculating means.

Further, change notification means may be provided to notify that the target vehicle speed has been changed.

[Function] While the constant speed running control means is in operation, if the slip ratio calculated by the slip ratio calculation means based on the detection results of the vehicle speed detection means and the detection results of the drive wheel speed detection means deviates from a predetermined slip ratio range. The torque adjusting means is controlled so that the torque applied to the drive wheels is reduced by the slip ratio reducing means, thereby reducing the slip ratio. or,
When the slip ratio deviates from the predetermined slip ratio range, the target vehicle speed changing means slightly reduces the target vehicle speed during constant speed driving. As a result, after the slip ratio falls within the predetermined slip ratio range, the vehicle is driven at a constant speed at a slightly reduced target vehicle speed, improving the safety of the vehicle.

Furthermore, by setting the speed reduction amount in accordance with the slip ratio calculated by the slip ratio calculation means, the target vehicle speed changing means can appropriately reduce the target vehicle speed by eliminating excess or deficiency in the speed reduction amount. can.

Further, by providing a change notification means for notifying that the target vehicle speed has been changed, it is possible to make the driver aware that the target vehicle speed for constant speed driving has been changed.

[Embodiment] An embodiment in which the present invention is applied to a vehicle equipped with a gasoline engine will be described below with reference to FIGS. 1 to 5.

As shown in FIG. 1, an intake pipe 2 and an exhaust pipe 3 are connected to an engine 1, and a throttle valve 5 for controlling the air flow rate is provided immediately before a surge tank 4 in the intake system. A throttle drive motor 6 as a torque adjusting means is connected to the throttle valve 5 for driving, and the throttle valve 5 is opened and closed by driving the motor 6. In this embodiment, a step motor is used as the slot/knottle drive motor 6.

Then, the intake air passes through the intake boat 7, the intake valve 8 opens, and the intake air is sucked into the combustion chamber 9. Further, fuel from a fuel injection valve 10 controlled by an electronic fuel injection device (not shown) is mixed with the air, and is ignited by a spark plug 11 to push down a piston 12 and generate engine torque. Gas after combustion is transferred to piston 1
When the exhaust valve 13 opens according to the movement of the exhaust pipe 3,
It is discharged through the catalytic converter 14.

A pressure sensor 15 is provided in the surge tank 4, and the pressure in the intake pipe is detected by the sensor 15.

Further, an intake temperature sensor 17 is attached to the air cleaner 16 provided at the tip of the intake pipe 2, and the intake air temperature is detected by the sensor 17. A throttle sensor 18 is attached to the throttle shaft of the throttle valve 5, and the sensor 18 detects the opening degree of the throttle valve (throttle opening degree). Furthermore, an air-fuel ratio sensor 19 is provided in the exhaust pipe 3 to detect the oxygen concentration in the exhaust gas. Also, engine 1
A cooling water temperature sensor 20 is provided to detect the temperature of engine cooling water. The rotation angle sensor 21 is attached to a distributor 23 that distributes the output of the igniter 22,
Outputs a signal as the crank rotates.

Information necessary for controlling the fuel injection valve 10 includes a pressure sensor 15, an intake air temperature sensor 17, a throttle sensor 1
8, the air-fuel ratio sensor 19, the cooling water temperature sensor 20, the rotation angle sensor 21, etc.

Further, the signal TA from the throttle sensor 18 among the signals from the respective sensors is also input to the throttle control unit 24 which functions as a constant speed running control means, a slip ratio calculating means, a slip ratio reducing means, and a target vehicle speed changing means. Further, an accelerator sensor 26 consisting of a potentiometer is attached to an accelerator pedal 25 provided in the driver's seat, and this accelerator sensor 26 outputs a signal AA (voltage) according to the amount of depression of the accelerator pedal 25 to the throttle control unit 24. . The throttle control unit 7) 24 controls the throttle drive motor 6 to control the opening degree of the throttle valve 5.

Furthermore, wheel speed sensors 29 and 30 as vehicle speed detection means are attached to the right front wheel 27 and the left front wheel 28, which are driven wheels of the vehicle, and their outputs are also sent to the throttle control unit 24. Wheel speed sensor 29°30 is right/left front wheel 27.2
The rotation speed of 8 is detected by an electromagnetic pickup. Driving force is transmitted from the engine 1 to a right rear wheel 31 and a left rear wheel 32, which are drive wheels of the vehicle, through a differential gear 33 and a drive shaft 34. Right rear wheel 31, left rear wheel 3
Wheel speed sensors 49 and 50 similar to the wheel speed sensors 29 and 30 are also attached to the wheel speed sensors 2, and their outputs are also sent to the throttle control unit 24.

The throttle control unit 24 is mainly composed of a microcomputer, and its internal structure is shown in FIG. A central processing unit (hereinafter referred to as CPU) via the pass line 35
36, read-only memory (ROM) 37, random access memory (RAM) 38, CRAM 39, internal timer 40, input counter 41, input port 43, and output circuit 44 carry out data inheritance.

Even when the ignition (IG) switch 45 is off, a voltage is applied to the CRAM 39 from the buffer battery 46 by a dedicated power supply circuit 47, so that the CRAM 39 retains its stored contents. In addition, the human power counter 41 is controlled by the wheel speed sensors 29 and 30 using the internal timer 40.
, 49. Measure the input period from 50.

The input board 43 is provided with several A/D conversion ports that A/D convert the input and input it as a 10-bit digital value. An accelerator operation amount signal from the accelerator sensor 26 and a throttle opening signal from the throttle sensor 18 are input to this A/D conversion boat.

In addition, the power supply circuit 48 is connected to the IG switch 4 from the battery 46.
A voltage of approximately 14 volts is supplied through the CRAM 39, which is converted to a stabilized 5 volt and supplied to circuits other than the CRAM 39. The output circuit 44 drives the throttle drive motor 6 based on data sent from the CPU 36 to change the opening degree of the throttle valve 5.

Then, the CPU 36 calculates the rotational speeds of the right and left front wheels 27.28 based on the signals from the wheel speed sensors 29 and 30, calculates the average value of these, calculates the vehicle speed, and calculates the vehicle speed. The opening degree of the throttle valve 5 is changed to control the torque applied to the right and left rear wheels 31 and 32 so that the vehicle speed reaches the target vehicle speed set by the speed setting device (the path shown).

Further, the CPU 36 determines the wheel speeds of the right and left rear wheels 31 and 32 based on the signals from the wheel speed sensors 49 and 50. Then, the CPU 36 determines the vehicle speed and the right and left rear wheels 31.
The slip rate S is calculated from the following formula based on the wheel speed of 32.

Further, when the calculated slip ratio is out of a predetermined slip ratio range, the CPU 36 rotates the throttle valve 5 in the closing direction to reduce the torque applied to the right and left rear wheels 31 and 32.

Furthermore, when the slip ratios of the right and left rear wheels 31, 32 deviate from a predetermined slip ratio range during constant speed driving, the CPU 36 adjusts the target vehicle speed slightly (10 km/h in this embodiment) during constant speed driving. ) is set to change to the decreased value.

Next, the target vehicle speed changing process executed by the CPU 36 will be explained based on the flowchart shown in FIG.

This process is executed every predetermined period (for example, 10 ma). First, in step 100, it is determined whether constant speed cruise control (C/C) is being executed. If it is determined that C/C is being executed, the slip rate reduction system is activated in step 101.
(TRC) Whether it is running or not, that is, when the slip ratio is out of the predetermined slip ratio range, the throttle valve 5 is rotated in the closing direction to reduce the torque applied to the right and left rear wheels 31 and 32. Determine whether or not it is decreasing. If it is determined in step 100 that C/C is not being executed, or if it is determined in step 101 that TRC is not being executed, the process moves to step 105 and the change permission flag FDEC is set to rOJ.
and ends this process.

If it is determined in step 101 that TRC is being executed, that is, a slip has occurred, the process proceeds to step 102, where it is determined whether the change permission flag FDEC is "0". In step 102, the change permission flag FDEC is set to r.
If it is determined that it is OJ, the change permission flag FDEC is set to "1" in step 103, and the target vehicle speed VSET for this constant speed driving is set to 10 km/h in step 104.
The value is changed to a value decreased by h, and this process ends. Also, in step 102, the change permission flag FDEC is set to rlJ.
If it is determined that this is the case, this process is terminated.

In this way, in this embodiment, if a slip occurs during constant speed driving, the TRC is activated as shown by ■ in FIG.
The control is executed to rotate the throttle valve 5 in the closing direction to reduce the speeds of the right and left rear wheels 31, 32, and to slightly reduce the target vehicle speed for constant speed driving (101 ua/h). As a result, the speeds of the right and left rear wheels can be automatically adjusted to match the speed of the road surface, and after the slip has subsided, it is possible to safely drive at a constant speed at the changed target vehicle speed even on rough roads. can do.

However, when a slip occurs while driving at a constant speed, TRC control is executed as shown in Figure 5.
If the speed of the left rear wheel 31, 32 is reduced and the slip subsides, and then the vehicle runs at a constant speed again at the original target vehicle speed, the vehicle will repeatedly slip, posing a safety problem.

In addition, in this embodiment, if slip occurs again at the changed target vehicle speed after the slip has subsided, TRC control is executed as shown by ■ in Fig. 4, and the target vehicle speed for constant speed driving is further changed slightly. (10 iun/h) [Since it is reduced, the safety of constant speed driving on rough roads can be ensured.

In addition, in the above embodiment, when the slip rate reduction control is executed during constant speed driving, the target vehicle speed for constant speed driving is slightly reduced (I Ok
m/h)N, but the speed reduction amount may be set in accordance with the slip ratio.

Further, an output circuit 51 may be provided in the throttle control unit 24, and a change indicator lamp 52 as a change notification means may be connected to the output circuit 51, and a constant speed running cancellation indicator lamp 53 may also be provided. When the target vehicle speed has been changed, the change display lamp 52 is turned on to make the driver aware of the change. Furthermore, if the target vehicle speed for constant speed driving is changed and becomes less than a predetermined value, the constant speed driving cancellation indicator lamp 53 can be turned on to indicate to the driver that constant speed driving has been canceled. .

FIG. 6 shows another process executed by the CPU 36 when the change indicator lamp 52 and the constant speed running cancellation indicator lamp 53 are provided. This process also takes place at a predetermined period (for example, 10
Executed every time (fertilization).

In step 200, it is determined whether C/C is being executed. If it is determined that C/C is being executed, step 20
1, it is determined whether or not slip has occurred in the right and left rear wheels 31 and 32 during TRC execution. When it is determined in step 201 that TRC is being executed, that is, a slip has occurred, the process proceeds to step 202, where it is determined whether a predetermined time (50III!I in this other example) has elapsed.

If it is determined in step 202 that the predetermined time has not elapsed, the process proceeds to step 203 and the slip rate S at that time is calculated.

In the following step 204, it is determined whether the slip rate S calculated in step 203 is larger than the maximum slip rate Smax within a predetermined time (50+a in this other example). If it is determined that the slip rate S is smaller than the maximum slip rate Smax in step 204, step 20
Proceed to step 6. Further, if it is determined in step 204 that the slip rate S is larger than the maximum slip rate Smax, step 2
05, the maximum slip rate Smax is the slip rate S
Then, in the following step 206, the change permission flag FDEC is set.
is set to "0" and this process ends.

Further, if it is determined in step 200 that C/C is not being executed, or if it is determined in step 201 that TRC is not being executed, the process moves to step 207 and the maximum slip rate Sm
Processing from step 206 onward is executed with ax as rOJ.

This process is repeatedly executed at a predetermined period, and step 20
If it is determined in step 2 that the predetermined time (50 m in this other example) has elapsed, the process moves to step 208 and the change permission flag FDE is set.
Determine whether C is rOJ and set change permission flag FD
If it is determined that EC is "1", the process advances to step 212. In this step 208, the change permission flag FDEC is set to “
0'', in the subsequent step 209, the amount of decrease VDEC in the target vehicle speed is determined by the function f (Sm
ax).

Next, in step 210, the target vehicle speed during constant speed driving is changed to a value that is decreased by the amount of decrease VDEC (VSET-t), and in step 211, the change permission flag FDEC is set to "1".
” and the process proceeds to step 212.

In step 212, the changed target vehicle speed VSET is set to 40.
It is determined whether or not the speed is less than 40 mm/h, and if it is determined that it is less than 40+m/h, the process proceeds to step 213 and after terminating the C/C control, the constant speed running cancellation indicator lamp 53 is is turned on for a predetermined period of time to indicate to the driver that constant speed driving has been canceled, and this process ends.

Also, in step 212, the target vehicle speed VSF, T is 40 m.
m/h or higher, the process proceeds to step 215, where the change indicator lamp 52 is turned on for a predetermined period of time to make the driver aware of this, and this process ends.

As described above, in the process shown in FIG. 6, when the slip rate reduction control is executed during constant speed driving, the maximum slip rate Smax within a predetermined time is calculated, and the maximum slip rate Smax is calculated.
Since the speed reduction amount VDEC is set according to x, the target vehicle speed during constant speed driving can be accurately reduced by eliminating excess or deficiency in the speed reduction amount. Furthermore, since constant speed driving control is canceled when the changed target vehicle speed becomes less than 40 km/h, safety can be further improved.

In both of the above embodiments, the slip ratio reduction control is performed to control the opening degree of the throttle nottle valve 5 in the gasoline engine, but the slip ratio reduction control may be performed to control the brake, ignition timing, or fuel amount.

Further, the present invention may be implemented in constant speed running control or slip rate reduction control that controls the amount of fuel in a diesel engine.

Further, in the above-described other example, the change notification lamp 52 is used as a change notification means for notifying a change in the target vehicle speed, but a buzzer may be used to notify a change in the target vehicle speed with sound.

Further, instead of the constant speed driving cancellation indicator lamp 53 that indicates that constant speed driving has been canceled, another buzzer may be provided.

In addition, in the above-mentioned other example, two lamps were provided, the change display lamp 52 and the constant speed driving cancellation display lamp 53, but only one lamp was provided.
Alternatively, only one lamp may be provided, and this lamp may blink when the target vehicle speed is changed, and may be lit continuously when constant speed driving is canceled.

[Effects of the Invention] As detailed above, according to the present invention, when the slip ratio deviates from the predetermined slip ratio range during constant speed driving, the vehicle speed is reduced so that the slip ratio falls within the predetermined slip ratio range. At the same time, the target vehicle speed for constant speed driving is slightly reduced and automatically adjusted to suit the road surface, making it possible to safely realize constant speed driving even on rough roads.

Further, the target vehicle speed changing means changes the speed reduction amount according to the slip ratio calculated by the slip ratio calculation means, so that the target vehicle speed can be appropriately reduced by eliminating excess or deficiency in the speed reduction amount. can.

Further, by providing a change notification means for notifying that the target vehicle speed has been changed, it is possible to make the driver aware that the target vehicle speed for constant speed driving has been changed.

[Brief explanation of the drawing]

Fig. 111 is a configuration diagram of the engine surroundings showing an embodiment embodying the present invention, Fig. 2 is an electric circuit diagram of the throttle control unit, Fig. 3 is a flowchart showing target vehicle speed change processing, and Fig. 4 is a diagram showing the present invention. Figure 5 is a graph showing the relationship between each wheel speed and the target vehicle speed when driving at a constant speed. Figure 5 is a graph showing the relationship between each wheel speed and the target vehicle speed when the target vehicle speed is not changed when driving at a constant speed. FIG. 7, which is a flowchart showing another process, is a graph showing the relationship between the amount of vehicle speed reduction and the slip ratio. In the figure, 6 is a throttle drive motor as a torque adjustment means, 24 is a throttle control unit as a constant speed running control means, a slip rate calculating means, a slip rate reducing means, and a target vehicle speed changing means, and 29 and 30 are vehicle speed detecting means. wheel speed sensor, 31° 32 is the rear wheel as the driving wheel, 49
．． 50 is a wheel speed sensor as a drive wheel speed detection means; 52
is a change display lamp as a change notification means. Patent applicant Nippondenso Co., Ltd. Agent Patent attorney On 1) Hironobu No. 41! f Fig. 5 1' bar missing 0゛A TRC sky lantern max

Claims (1)

[Scope of Claims] 1. Torque adjustment means for adjusting the torque applied to the driving wheels of the vehicle; vehicle speed detection means for detecting the traveling speed of the vehicle; constant speed driving control means for controlling the torque adjustment means to perform constant speed driving so as to achieve a target vehicle speed; driving wheel speed detecting means for detecting the speed of the driving wheels; and the vehicle speed detecting means and the driving wheel speed. a slip ratio calculation means for calculating a slip ratio based on the detection result of the detection means; and reducing the torque applied to the drive wheel when the slip ratio calculated by the slip ratio calculation means deviates from a predetermined slip ratio range. slip ratio reducing means for controlling the torque adjusting means; and when the slip ratio detected by the slip ratio calculating means deviates from a predetermined slip ratio range during the operation of the constant speed running control means, 1. A vehicle speed control device comprising: target vehicle speed changing means for slightly reducing a target vehicle speed during fast running. 2. The vehicle speed control device according to claim 1, wherein the target vehicle speed changing means sets the speed reduction amount according to the slip ratio calculated by the slip ratio calculating means. 3. The vehicle speed control device according to claim 1, further comprising change notification means for notifying that the target vehicle speed has been changed by the target vehicle speed change means.