JPH0224687B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle speed control device, and more particularly, to a vehicle speed control device that controls the speed of a vehicle using an internal combustion engine as a drive source to a desired speed.

Generally, this type of vehicle speed control device is configured to obtain a signal indicating the vehicle speed at any given time using a vehicle speed detector, and to control the engine speed so that the vehicle speed indicated by the signal becomes a desired value. However, conventional vehicle speed detectors that have been used for this purpose consist of a reed switch and a magnet, and are configured to output a pulse signal with a frequency that corresponds to the number of rotations of the vehicle speedometer cable. The vehicle speed control device is
The vehicle speed is controlled in accordance with data indicating the vehicle speed value at each time calculated based on the period of this pulse signal. Although the vehicle speed detector configured as described above is simple, since the distance between the magnetized positions of each magnetic pole of the magnet is uneven, the speed detector is configured as follows:
Even if an attempt is made to control the engine digitally, non-uniform magnetization will cause control errors such as hunting in the running speed and deviation from the target value.
This had the problem of reducing the accuracy of control over traveling speed. To remove this defect,
Although it is possible to improve the accuracy of the magnetized position of the magnetic poles of the magnet, such a magnet is very expensive and causes another problem of causing a large increase in manufacturing cost. Furthermore, if the vehicle speed is calculated based on the period of the pulse signal when the magnet rotates once, the accuracy of the magnetized position of the magnetic pole of the magnet will not affect the accuracy of the detected vehicle speed. Since the period becomes longer, desired digital control cannot be performed quickly, resulting in a decrease in control accuracy.

To solve this problem, a speed detection device has been proposed that mechanically detects the gear ratio in the transmission mechanism and calculates the vehicle speed based on the detected gear ratio and the mechanical speed at that time. (Japanese Unexamined Patent Publication No. 137861/1983).

However, since this proposed speed detection device detects the gear ratio set in the transmission by providing a device with a mechanical structure, it is necessary to provide a mechanical switch for detecting the gear shift position in the transmission. The problem is that the configuration is complicated and expensive.

Accurate vehicle speed detection can also be carried out by mounting a vehicle speedometer on the axle, but this results in a significant increase in cost, which poses a problem in terms of economic efficiency. Further, in such a vehicle speed control device, if a failure occurs in a sensor that detects vehicle speed or engine speed, it is necessary to detect this to ensure safety of control. This type of speed sensor abnormality detection device selects and outputs the lower limit and upper limit set values according to the gear position based on the gear position signal from a memory device that stores the lower limit and upper limit value of the vehicle speed at each gear position of the automatic transmission. A speed sensor abnormality detection device has been proposed which uses a comparator to compare the upper limit value and the speed signal, and detects an abnormality when the speed signal falls outside the range of the lower and upper limit set values. (Japanese Patent Application Laid-open No. 57-94662). However, this proposed abnormality detection device has a problem in that it is difficult to distinguish between a case where the vehicle speed or engine speed becomes zero and a case where the sensor fails.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an internal combustion engine vehicle that is capable of accurately controlling vehicle speed without installing an expensive vehicle speed sensor, and also that is capable of reliably detecting failures in the vehicle speed sensor and the engine speed sensor. The purpose of the present invention is to provide a vehicle speed control device for use in vehicles.

The present invention provides a vehicle speed control device for controlling the traveling speed of a vehicle using an internal combustion engine as a drive source to a desired value. a vehicle speed sensor for outputting an associated vehicle speed signal, a detection means for detecting a gear position of the transmission in response to the rotation signal and the vehicle speed signal, and means for setting a desired target vehicle speed;
a speed adjusting means for adjusting the speed of the internal combustion engine; and a control means for calculating an actual vehicle speed based on the detection result from the detecting means and the rotation signal and controlling the speed adjusting means so as to obtain the target vehicle speed. , characterized in that it includes means for calculating a speed ratio between the rotation speed and the vehicle speed based on the rotation signal and the vehicle speed signal, and means for determining a failure of the rotation sensor and the vehicle speed sensor based on the value of the speed ratio. has.

The control means calculates the product of the predetermined gear ratio and the engine speed at the gear position detected by the detection means, and compares the data representing the multiplication result with the data representing the target vehicle speed, thereby controlling the vehicle speed. is configured to do this. According to this configuration, since the vehicle speed sensor is used only to detect the gear position as described above, high accuracy is not required. On the other hand, since vehicle speed is controlled based on the internal combustion engine speed and the gear ratio corresponding to the current gear position of the transmission, the accuracy of vehicle speed control depends on the accuracy of the rotation sensor that detects the rotational speed of the internal combustion engine. I will do it. Generally, the detection accuracy of a rotation sensor that detects engine speed is several steps higher than that of a vehicle speed sensor, so it is possible to configure a device with higher control accuracy than conventional vehicle speed control devices. In addition, by checking whether the gear ratio value obtained based on the rotation signal and the vehicle speed signal is within a predetermined normal range, a failure detection system is configured by mutual monitoring between the vehicle speed sensor and the rotation sensor. The reliability of the device is significantly improved.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows a block diagram of an embodiment of a vehicle speed control device according to the present invention. The vehicle speed control device 1 is a device for controlling the vehicle speed of a vehicle 3 using an internal combustion engine 2 as a drive source to an arbitrarily set desired target vehicle speed, and for detecting the rotational speed of the internal combustion engine 2. The vehicle 3 includes a rotation sensor 4 and a vehicle speed sensor 5 for detecting the vehicle speed of the vehicle 3. The rotation sensor 4 is connected to the crankshaft 6 of the internal combustion engine 2.
A signal gear plate 7 fixed to the signal gear plate 7 and an electromagnetic coil 8 disposed opposite to the signal gear plate 7.
This is a known sensor in which a voltage is induced in the electromagnetic coil 8 each time each cog formed around the signal gear plate 7 approaches and separates from the electromagnetic coil 8. Therefore, the rotation sensor 4 outputs an output at time intervals related to the rotation speed of the internal combustion engine 2. A pulse train signal S ₁ consisting of pulses is output,
A correspondingly provided interface circuit (I/
F) After being waveform shaped in 9, it is output as the first signal _S2 . On the other hand, the vehicle speed sensor 5 is connected to a traveling device 1 connected to an internal combustion engine 2 via a transmission 10.
The magnet plate 12 is connected to a meter cable (not shown) of a vehicle speedometer (not shown) and is comprised of a magnet plate 12 that rotates as the meter cable rotates, and a reed switch 13. As shown, the magnet plate 12 is alternately magnetized to N and S poles, and rotates as the meter cable rotates to turn the reed switch 13 on and off. The reed switch 13 is connected to an interface circuit (I/
F) 14, and its output side outputs a second signal _S3 whose level changes in response to whether the reed switch 13 is turned on or off. As can be seen from the above description, the second signal _S3 is a pulse train signal whose period changes in relation to the vehicle speed.

The first signal S ₂ having information regarding the speed of the internal combustion engine 2 and the second signal S ₃ having information regarding the vehicle speed are input to an input/output circuit (I/O) 15, where the respective signals are First data indicating the period
_D1 and second data _D2 are created as binary digital data. The first data _D1 indicating the period of the first signal _S2 output in this way and the second signal
Second data D ₂ indicating the period of S ₃ is stored in memory 17 by central processing unit (CPU) 16 .

The central processing unit 16 stores a program for controlling the vehicle speed to a predetermined target vehicle speed, and responds to control signals _S4 from each operation switch (not shown) provided on the control panel 18. The program is executed. In the central processing unit 16, the position of the fuel adjustment member required to bring the vehicle speed to the required target speed is calculated based on each input data D ₁ , D ₂ and the control signal S ₄ . The calculation result in is output from the input device ₁₅ as a position signal S5 indicating the adjustment position of the fuel adjustment member (not shown) of the internal combustion engine 2, and is outputted from the input device 15 to the drive circuit 19.
is input. A drive signal S ₆ is output from the drive circuit 19 in response to the position signal S ₅ and is applied to an actuator 20 connected to a fuel adjustment member (not shown), whereby the adjustment position of the fuel adjustment member is adjusted to the position signal S ₅ . controlled accordingly.

FIGS. 2a and 2b show a flowchart of a program for controlling the vehicle speed described above. First, in step a, it is determined whether the control system shown in FIG. 1 is normal or not. If the control system is normal, the second data is
D ₂ is read and the second data D ₂ is transferred to memory 1.
7 and checks whether the value of the second data _D2 is within a predetermined normal range (step c). If there is an abnormality in the control system,
Proceed to step d, vehicle speed control is completely released,
A cruise lamp (not shown) provided in the control panel 18 (FIG. 1) is turned off (step e).
If the determination result in step c is YES,
In step f, the value of vehicle speed V is calculated based on the second data _D2 . This operation is performed on the second data
This is done by multiplying the reciprocal of D ₂ by a predetermined coefficient, and data regarding vehicle speed can be easily obtained. On the other hand, if the calculation result in step c is NO, it is first determined in step g whether or not the vehicle is in a constant speed running control state, and if the determination result is NO, the process proceeds to step f. If the determination result is YES, it is determined in step h whether or not the value of _D2 being outside the normal range has been detected a predetermined number of times _N1 consecutively in step c. If the determination result in step h is NO, proceed to step f,
If YES, a message indicating that the vehicle speed sensor is malfunctioning is displayed (step i), and the control is completely canceled (step d).

That is, regarding the value of the second data _D2 , if the value is outside the normal range _one or more consecutive times during constant speed driving, it is determined that the vehicle speed sensor is malfunctioning, and the control is completely canceled. In other cases, the vehicle speed is calculated based on the data _D2 in step f.

The calculation result of the vehicle speed is 28Km/
It is determined whether or not it is greater than or equal to h, and if the determination result is NO, the control is completely canceled. This means that the vehicle speed is 28
When the speed is slower than Km/h, there is virtually no need for vehicle speed control, so the control is forcibly canceled. If the vehicle speed is 28km/h or higher, step k
The gear position is determined at .

The gear position is determined based on the vehicle speed V calculated in step f and the engine rotational speed N, which is separately calculated based on the first data _D1 . That is, if the ratio between vehicle speed V and rotational speed N is defined as gear ratio R, gear ratio R≡N/V, and therefore R≡
It becomes D ₁ /D ₂ . By the way, the value of the gear ratio R is a unique value determined by the gear position in the transmission 10, and the gear ratio is R ₁ at the 1st gear position and R 1 at the 2nd gear position.
R ₂ and third gear position R ₃ , the gear position at any given time can be determined by the ratio of D ₁ /D ₂ . In this embodiment, the predetermined gear ratio R ₁ at each gear position,
Setting a first gear ratio region, a second gear ratio region, and a third gear ratio region including R ₂ and R ₃ , respectively,
It is configured to determine which gear ratio range the value of D ₁ /D ₂ falls into, and to detect the gear position at that time from this result. Abnormal gear ratio regions (a), (b), (c), and (d) are set at both ends of each gear ratio region, and it is determined to which region the value of D ₁ /D ₂ belongs. Therefore, the gear position and the abnormality of the vehicle speed sensor are determined.

_The above-mentioned determination procedure will be explained in detail with reference to _FIG . A determination is made as to whether or not the vehicle is running. If the vehicle is not traveling at a constant speed, the process proceeds directly to step m, but if the vehicle is traveling at a constant speed, it is determined whether or not the vehicle speed sensor is malfunctioning based on the calculated gear ratio. Executed by q. That is, in step m, it is determined whether the gear ratio is normal or not (whether the gear ratio belongs to the ranges (a) to (d) shown in FIG. 3), and if the determination result is NO, further, It is determined whether the gear ratio abnormal state has been detected a predetermined number of times N ₂ times in a row, and if it is determined that the gear ratio is abnormal N ₂ times in a row, the control is completely canceled. In this way, by checking whether the gear ratio is normal or not, it is possible to determine a failure through mutual monitoring between the rotation sensor 4 and the vehicle speed sensor 5, which has the advantage of improving control reliability. There is. If the determination result in step p is NO, proceed to step m.

If it is determined that the gear ratio is normal, it is further determined in step 0 whether or not the gear position determined in step k has changed, and if no change in gear position is detected, The process proceeds to step m, and when a change in gear position is detected, step q determines whether or not the gear position has changed a predetermined number of times _N3 consecutively. In this case, it is normally impossible to perform a gear change operation in which a change in gear position is detected _three times in a row. The release is performed (step d). On the other hand, even if there is a change in gear position, if there are no changes _N3 times in succession, the vehicle speed sensor is considered to be normal, and the process proceeds to step m.

Here, if at least one of the determination results in steps p and q is YES,
It is also possible to proceed to step d via step r, which indicates a failure of the vehicle speed sensor, and to completely cancel the control.

Step m is a step in which the vehicle speed V is calculated from the gear position determined in step k and the pre-calculated rotational speed N. Here, the value of the vehicle speed V is detected by the vehicle speed sensor 4. It is calculated with the same accuracy as the rotational speed and is not directly related to the output of the vehicle speed sensor 5. That is, since the rotational speed N detected with high precision is converted into the vehicle speed V in consideration of the determination result in step k, it is possible to detect the vehicle speed with high precision.

When the value of the vehicle speed V at each moment is calculated in this way, the status of each switch on the control panel 18 is checked (step s), and according to the results,
Temporarily release the control (step t), so that the vehicle speed value obtained above becomes the desired target vehicle speed.
Proceed to either step of performing PI control (step u) or generating a ramp function (step v). If the temporary release has been performed, proceed to step e. Further, after the ramp function is generated in step v, the process proceeds to step u.
After the PI control calculation is performed, the cruise lamp is turned on (step w), and a check is made to see if gear slippage has occurred (step x). A check for gear slippage can be performed, for example, by monitoring whether the value of the gear ratio R has become abnormally large.
(Step _y )
Completely release control. By providing such a step, by monitoring the gear position during constant speed driving, even if the clutch switch fails, it is possible to detect that a gear change has been performed, cancel constant speed driving, and restart the engine. It also has the advantage of preventing blow-up. If gear disengagement is not detected, or if it is detected but not _N4 times in a row, proceed to step z.

Step z is the target value Qdrive of the fuel supply amount according to the accelerator operation amount and the value of the fuel supply amount necessary to make the vehicle run at a constant speed at each time.
This is a step in which a magnitude comparison is made with Qcruise and the larger data value is set as position control data indicating the target position of the fuel adjustment member. The position control data obtained in this manner is outputted as a position signal _S5 via the input/output device 15.

According to such a configuration, the gear position of the transmission 10 is determined from the vehicle speed information obtained from the vehicle speed sensor 5 and the engine speed information obtained from the rotation sensor 4, and the gear position determined in this way is determined. Since the vehicle speed is calculated from the information and the engine speed information, the accuracy of the obtained vehicle speed information is almost the same as the detection accuracy of the rotation sensor 4. As a result, even if a conventional inexpensive vehicle speed sensor that obtains vehicle speed information from the rotational speed of a rotating cable of a vehicle speedometer is used as the vehicle speed sensor 5, extremely accurate vehicle speed information can be obtained, and the vehicle speed In addition to being able to perform control with high precision, control responsiveness is also significantly improved. The gear position can be determined based on the ratio between the engine speed and the vehicle speed. Therefore, when used for this purpose, the detection accuracy of the vehicle speed sensor may be low, and the conventional vehicle speed sensor described above can be used for this purpose. is sufficient to achieve that purpose. Therefore, vehicle speed control can be performed accurately without using a highly accurate and expensive vehicle speed sensor.

In addition, in the above embodiment, the determination of whether the gear ratio is normal or abnormal in step n is performed when the gear ratio R is in the range (A) or
Although the determination is made based on whether or not any of (d) exists, the range of each of these regions can be determined as appropriate, taking into account the accuracy of the vehicle speed sensor, etc.

According to the present invention, the gear position of the transmission is indirectly detected based on the vehicle speed information and the engine speed information, and the transmission gear position is calculated based on the thus detected gear position information of the transmission and the engine speed information. Since the vehicle speed is controlled based on vehicle speed information, vehicle speed can be detected accurately even when using a conventional inexpensive vehicle speed sensor. As a result, vehicle speed can be detected without using an expensive vehicle speed sensor. A special effect can be obtained in that control can be performed with high precision and responsiveness.

Furthermore, the configuration calculates the speed ratio between the engine rotational speed and the vehicle speed based on the information from the vehicle speed sensor and the information from the rotation sensor, and determines the failure of each sensor based on the value of this speed ratio. It is possible to configure a failure detection system based on mutual monitoring between the vehicle speed sensor and the rotation sensor, which can easily identify the failure of one of the sensors, thereby significantly improving the reliability of the device. It is also possible to obtain excellent effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of a vehicle speed control device according to the present invention, and FIGS.
FIG. 3 is a flowchart of the control program loaded into the device shown in the figure, and is an explanatory diagram for explaining the determination of whether the calculated gear ratio value is normal or abnormal. 1...Vehicle speed control device, 2...Internal combustion engine, 3...Vehicle,
4... Rotation sensor, 5... Vehicle speed sensor, 10... Transmission, 11... Travel device, 15... Input/output device, 16...
Central processing unit, 19...drive circuit, 20...actuator, _S1 ...pulse train signal, S2...first signal, _S3 ...second signal, _S4 ...control signal, _{S5 ...} position signal, _D1 ...first Data, D ₂ ...Second data.

Claims (1)

[Claims] 1. In a vehicle speed control device for controlling the running speed of a vehicle using an internal combustion engine as a drive source to a desired value,
A rotation sensor outputting a rotation signal related to the rotation speed of the internal combustion engine, a vehicle speed sensor outputting a vehicle speed signal related to the vehicle speed, and detecting a gear position of the transmission in response to the rotation signal and the vehicle speed signal. a detection means, a setting means for setting a desired target vehicle speed, a speed adjustment means for adjusting the speed of the internal combustion engine, and calculating an actual vehicle speed based on the detection result from the detection means and the rotation signal; control means for controlling the speed adjustment means so that the target vehicle speed is obtained in response to the setting means; and means for calculating a speed ratio between the rotation speed and the vehicle speed based on the rotation signal and the vehicle speed signal. A vehicle speed control device comprising: means for determining failure of the rotation sensor and the vehicle speed sensor based on the value of the speed ratio.