JPS6111816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic speed control method, and in particular to an automatic speed control method suitable for controlling the running speed of an automobile to a constant level, and also for a motor vehicle with a large load fluctuation, such as a stationary emergency power generator. This invention relates to an automatic control method suitable for constant speed control of equipment.

Various types of automatic speed control methods, particularly automatic speed control methods for controlling the speed of an automobile to be constant, have been considered in the past. FIG. 1 is a system diagram showing an example of a device for carrying out a conventional automatic speed control method for automobiles, in which 1 is a speed signal detector that generates a pulse signal with a frequency proportional to the speed, and 2 is a speed signal detector that generates a pulse signal with a frequency proportional to the speed. The pulse signal input from device 1 is sent to an F-V converter (frequency-voltage converter).
3 is a pulse generator that generates a pulse signal of a constant frequency; 4 is a gate circuit that sends the pulse signal to a counter 6 when the set switch 5 is turned on; 7 is a DA converter that converts the counting result of the counter 6 into an analog voltage. Then, while turning on the set switch 5,
The output of the A converter 7 and the output of the speed signal generator 2 are compared by the comparator 8, and when both outputs match, the output of the comparator 8 closes the gate circuit 4 and stops counting the pulse signals. Then, the speed at that time is stored in the counter 6. After that, speed signal generator 2
The error amplifier 9 compares and amplifies the difference between the voltage output proportional to the actual speed and the output obtained by converting the set speed stored in the counter 6 into an analog voltage. - The negative pressure converter 11 converts the magnitude of current into the magnitude of negative pressure from the negative power source 12, and further opens and closes the throttle valve 15 of the gasoline engine via the negative pressure-suction force converter 13 and link mechanism 14. The speed of the car was controlled at a constant level.

However, in the conventional method described above, an F-V converter is used as the speed signal generator 2, and a D-V converter is used to convert the counting results of the counter 6.
Due to the use of A converters, the accuracy of speed measurement of vehicles is insufficient, and the response characteristics of F-V converters make it difficult to quickly and accurately measure speeds, especially when the speed is slow and the speed pulse frequency is low. It had drawbacks such as the inability to respond.

The purpose of this invention is to solve the above-mentioned drawbacks of the prior art, and to significantly increase accuracy and provide excellent responsiveness by digitally processing everything from measuring the actual speed to calculating the difference between the actual speed and the set speed. An object of the present invention is to provide an automatic speed control method that can automatically perform fine speed control.

The automatic speed control method of the present invention counts speed pulses within a certain time T ₀ of a frequency proportional to the speed generated from a speed signal detection means, and calculates the speed pulses from the speed pulse counting result N and a certain integer n ₀ .
Generate auxiliary pulses with a period determined by T ₀ / (N+1)・n ₀ , count the auxiliary pulses from the rising edge of each speed pulse, and calculate the speed pulse count result N after a certain period of time.
Approximately calculate N+n/n ₀ from and the auxiliary pulse count result n as a quantity proportional to the actual speed, compare this calculated value with the value corresponding to the set speed, and generate an output signal corresponding to the difference. It is characterized in that the output signal is used to drive an acceleration/deceleration mechanism of the prime mover, such as a throttle valve or a control rack, via an electro-mechanical conversion means.

Next, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a system diagram of an apparatus for carrying out an automatic speed control method according to an embodiment of the present invention, and particularly shows the case where the apparatus is applied to an automobile equipped with a gasoline engine.

In other words, the automatic speed control method shown in the figure uses a speed signal detector 21 that generates speed pulses with a frequency proportional to the speed of the vehicle.
, a clock pulse generator 22 that generates a clock pulse with a cycle sufficiently smaller than the speed pulse cycle at the maximum speed, and a constant time generator that generates a constant time T ₀ that is sufficiently longer than the speed pulse cycle at the lowest speed. The clock pulse generator 2 is provided with means, that is, a constant time generator 23, and an auxiliary pulse generator 24 that generates auxiliary pulses with a period corresponding to the counting result of the speed pulses.
2 provides a clock pulse to a constant time generator 23 and an auxiliary pulse generator 24. Also, for a certain period of time
The start of T ₀ is synchronized with the rise of the speed pulse at the start of measurement. Furthermore, as shown in FIG. 2, a speed pulse counter 25 that counts speed pulses within a certain period of time is further provided.
, an auxiliary pulse counting means, ie, an auxiliary pulse counter 26, which counts auxiliary pulses with a period corresponding to the count content of the speed pulse counter 25, and the speed pulse counting result N and the auxiliary pulse count at the end of the constant time _T0 . It is provided with an actual speed calculation means, ie, a speed calculator 27, which approximately calculates N+n/ _n0 from the result n as a quantity proportional to the actual speed, and a set speed storage means that stores the set speed. This set speed storage means consists of a set switch 28, a gate circuit 29, and a speed memory 30. When the set switch 28 is pressed, the gate circuit 29 is opened, and the speed of the vehicle at that time is sent to the speed memory 30 and stored. Ru.

Thereafter, a comparison between a value approximately calculated as a quantity proportional to the actual speed and a value corresponding to the stored set speed is performed by the speed comparison means, that is, the error calculator 31. The calculation will be explained in more detail with reference to FIG.

The speed pulse counter 25 described above operates for a certain period of time.
It is 0 at the rising edge of T ₀ , and from the next speed pulse it is counted as 1, 2,...N, and for a certain period of time.
At the end of T ₀ , the pulse count value N is temporarily held. Further, the auxiliary pulse generator 24 generates auxiliary pulses with a period determined by the following equation (1) in accordance with the pulse count value N of the speed pulse counter 25 and in synchronization with the rising edge of the speed pulse.

τ=T ₀ /(N+1)n ₀ ...(1) In equation (1), n ₀ is a constant integer, e.g.
It is 16.

Furthermore, the auxiliary pulse counter 26 is 0 at the rising edge of each speed pulse, and counts 1, 2, _.
At the end of , the pulse count value n is temporarily held.

Therefore, if the period of the speed pulse is T _x and the speed of the car is V _x , then as shown in Figure 3, T ₀ = N・T _x +τ・n = N・T _x +T ₀ /(N+1)n ₀・n...(2) is obtained. Therefore, T _x = T ₀ /N {1-n/(N+1) n ₀ } ...(3) is obtained, and furthermore, V _x = K/T _x = K・N/T ₀ {1- n/(N+1)n
₀ } ^-1 ...(4) (K is a constant) is obtained, and the speed V _x is determined.

By the way, the above formula (4) is not suitable for digital calculations because it involves division, so if we obtain an approximate formula by setting n/(N+1)n ₀ ≪1 and N/N+1≒1 so that it can be calculated using only multiplication. It will look like this:

V _x ≒K/T ₀ (N+n/n ₀ )...(5) Therefore, let ε be the error in the velocity V _x obtained from the approximate equation (5) with respect to the exact equation (4), then ε=K /T ₀ (N+n/n ₀ )-K・N/T ₀ /{1-n/(N+1)・n ₀ }=K/T ₀ (N+n/n ₀ )-K/
T ₀ {N+N/N+1・n/n ₀ +N/(N+1) ² (n/n ₀ ) ² +……}=K/(N+1)T ₀・n/n ₀ (1−n/n ₀ )/ {1-1/N+
1(n/n ₀ )}...(6), and ε becomes 0 at n=0 and n=n ₀ .

Among these, n = n ₀ is a constant time T ₀ from equation (1)
Since this is the maximum value of n within the vehicle speed range in which N vehicle speed pulses fall, the error is 0 at the speed where N・T _x equals T ₀ , that is, the boundary vehicle speed where N increases or decreases.
Therefore, the measured value changes continuously even before and after such vehicle speed, and a stable vehicle speed control state is always maintained.

Here, when n ₀ = 16, the ratio of the error to the exact value when N≧5 is maximum when N = 8.
Although it can be easily proven using equations (4) and (6), the maximum is 0.83% or less, so there is no problem in practical calculations using equation (5).

Incidentally, at first glance, equation (5) appears to include division, but since K/To and 1/n ₀ are constants, they can be set in advance, and the calculation does not include division. In addition, in order to achieve the vehicle speed control function in an actual device, it is not necessary to know the absolute value of the vehicle speed according to equation (5), but it is necessary to calculate N + n / n ₀ and compare it as a value proportional to the set vehicle speed or the actual vehicle speed. Needless to say, it's a good thing.

Furthermore, this approximation formula is devised so that the error of the approximation formula with respect to the exact formula is 0, that is, the measured value changes continuously, even at the boundary where N increases or decreases (±1) due to changes in the vehicle speed pulse period due to changes in vehicle speed. Moreover, it has the great advantage of suppressing the maximum error to a sufficiently tolerable level within the practical vehicle speed range, thus enabling stable vehicle speed control.

Furthermore, when using a reed switch or the like to detect the rotation of a multi-pole magnet driven by a speedometer cable as a speed signal detection means, the intervals between vehicle speed pulses are not necessarily constant even at the same vehicle speed due to the accuracy of the magnet device. Not,
The method of calculating vehicle speed by directly measuring the pulse interval using clock pulses has the disadvantage that stable vehicle speed cannot be obtained. On the other hand, in this invention, the vehicle speed is calculated using the pulse count result N and the auxiliary pulse count result N at a speed within a time T ₀ that is sufficiently longer than the speed pulse period, so that an average pulse period can be obtained. Even when the above-mentioned detection means is used, there is an advantage that stable vehicle speed control can be performed.

In this way, the value of the amount proportional to the actual speed is calculated by the speed calculator 27, and the difference between the value calculated as the amount proportional to the actual speed and the value corresponding to the stored set speed. is calculated by the error calculator 31. This calculation result is input to the output signal generator 32. For example, if the difference between the value proportional to the actual speed and the value corresponding to the set speed is 0, an output current with a constant amplitude and a energization time rate of 50% is output. The negative pressure source 33
For example, negative pressure from an automobile intake manifold is introduced, and the current-negative pressure converter 34 converts the change in current into a change in negative pressure. Further, the negative pressure change is converted into a change in suction force by the negative pressure-suction converter 35, and the throttle valve 37 is driven via the link mechanism 36. At this time, if the actual speed is greater than the set speed, the throttle valve 37 is driven in the direction of decreasing the actual speed, and in the opposite case, the throttle valve 37 is driven in the direction of increasing the actual speed.
By driving the vehicle, the vehicle can be driven at a constant set speed. Note that the set speed is canceled once due to braking, etc.
Any value can be stored by pressing the set switch 28 again at the desired speed.

In the embodiment described above, the negative pressure source 3 is used as an electro-mechanical conversion means linked to the output signal generator 32.
3. The current-negative pressure converter 34, the negative pressure-attractive force converter 35, and the link mechanism 36 are combined to finally drive the throttle valve 37, but it is not necessary to use electricity as described above. - Of course, it is not limited to mechanical conversion means. In addition, in diesel engines that have a structure in which the speed is changed by increasing or decreasing the fuel injection amount by rotating the plunger, if the control rack that rotates the plunger is connected to the link mechanism, the gasoline engine Good constant speed control can be performed as in the case.

Next, another embodiment of the automatic speed control method according to the present invention will be described.

In the first embodiment, the speed signal calculation processing device 40 for calculating the actual speed was composed of the parts from the clock pulse generator 22 to the output signal generator 32 shown in FIG. In the embodiment, this is configured by a microcomputer. 4 and 5 will be explained below.

In this embodiment, as shown in FIG. 4, a digital signal, which is a speed pulse at a constant time T ₀ with a frequency proportional to the speed of the vehicle, generated from a speed signal detection means, that is, a speed signal detector 41, is supplied to a microcomputer 50. Here, the value of the quantity proportional to the actual speed is calculated in the same manner as explained with reference to FIG.
This, together with the introduction of negative pressure from the negative pressure source 53, converts changes in current into changes in negative pressure. The output of this current-negative pressure converter 54 is transmitted to the throttle valve 57 via the negative pressure-attractive force converter 55 and the link mechanism 56, and the throttle valve 57 is driven in the same manner as explained with reference to FIG. , so that the car can always run at a value corresponding to a constant set speed. In this embodiment as well, the set speed can be set to a desired speed by the set switch 48 after it has been canceled by braking or manually.

Next, the calculation process of the value of the quantity proportional to the actual speed by the microcomputer 50 will be explained in more detail with reference to the flowchart of FIG.

In step 101 of FIG. 5, the system power is switched on. As a result, the speed signal detector 4
1 starts generating velocity pulses and supplies this pulse to the microcomputer 50. In the microcomputer 50, initial settings are performed in step 102, and as shown in step 103, the built-in memory area for time T (used as a time memory in general-purpose memory, hereinafter expressed similarly),
The memory area for vehicle speed pulse count value N and the memory area for auxiliary pulse count value n are cleared. Next, in step 104, the presence or absence of a rising edge of the output pulse (speed pulse) of the speed signal detector 41 is detected, and when it is determined that there is a rising edge of the speed pulse, a memory area for the vehicle speed pulse count value N is stored as shown in step 105. At the same time, it clears the memory area of the auxiliary pulse count value n, and at the same time sets the time τ determined by T ₀ / (N + 1) · n ₀ from the value of N and a fixed integer n ₀ , and determines that there is no pulse rise. If so, the memory area for the auxiliary pulse count value n is incremented as shown in step 106.
Next, in step 107, the above-mentioned time τ is added to the memory area of time T. Next, in step 108, the input of the set switch 48 is scanned, and in step 10
At step 9, it is determined whether or not this switch has been operated. If the switch has not been operated, the process proceeds to step 110, and if the switch has been operated, the process proceeds to step 113. In step 110, steps 104 to 1 are performed.
The timer 110 is set so that the computer processing time for one round returning to step 104 via step 11 is the above-mentioned time τ. In step 111, the contents of the memory area at a preset constant time T ₀ are compared with the contents of the memory area at time T, and if T<T ₀ , the process returns to step 104 and T
If ≧T ₀ , proceed to step 112. In steps 112 and 112', the above-mentioned N+n/ _n0 is approximately calculated as a quantity proportional to the actual speed using the obtained pulse count values N, n, time τ, and predetermined time _T0 . The calculated value is entered into the actual speed memory area, and at the same time, it is compared with the value corresponding to the set speed, which is the contents of the set speed memory area, and an output signal corresponding to the difference is calculated to generate a control output. Further, in step 113, the contents of the actual speed memory area at that time are stored in the set speed memory area, and the process returns to step 103.

In addition, in a loop that passes from step 104 to step 110 and returns directly to step 104 again, an NP instruction is inserted so that the program execution time is constant no matter which branch loop is passed through as long as it is between the same N. Then adjust the steps of the program.

As described above, according to the present invention, the calculation of the difference between the value of the amount proportional to the actual speed and the value corresponding to the set speed and the output of the control signal are all digitally processed, which is significantly better than the conventional method. Accuracy can be increased, and the calculations described above can be sufficiently processed using conventional general-purpose 4-bit microcomputers that are mass-produced and sold. can be provided. In addition, the maximum value of the count content n of the auxiliary pulse is a constant relatively small integer n ₀
This has the advantage that the number of bits required for the counting means is small.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an example of a device that implements a conventional automatic speed control method, FIG. 2 is a system diagram of a device that implements an automatic speed control method according to an embodiment of the present invention, and FIG. 3 is a speed pulse FIG. 4 is a system diagram of a device implementing an automatic speed control method in another embodiment of the present invention, and FIG. 5 is a flowchart of the arithmetic processing of the microcomputer shown in FIG. 4. It is an explanatory view showing a chart. 21, 41... Speed signal detector, 22... Clock pulse generator, 23... Fixed time generator, 2
4... Auxiliary pulse generator, 25... Speed pulse counter, 26... Auxiliary pulse counter, 27... Speed calculator, 28, 48... Set switch, 30...
... Speed memory device, 31 ... Error calculator, 32 ... Output signal generator, 33, 53 ... Negative pressure source, 34, 5
4...Current-negative pressure converter, 35, 55...Negative pressure-
Attraction force converter, 36, 56... link mechanism, 3
7, 57...throttle valve, 40...speed signal arithmetic processing device, 50...microcomputer.

Claims (1)

[Claims] 1. Count the speed pulses within a certain time T ₀ of a frequency proportional to the speed generated from the speed signal detection means, and calculate _{T 0 /} ( Count the auxiliary pulses with a period determined by N+1)・_n0 from the rise of each speed pulse, and calculate N+n/ _n0 in proportion to the actual speed from the speed pulse counting result N and the auxiliary pulse counting result n after a certain time _T0 . The calculated value and the value corresponding to the set speed are compared to generate an output signal corresponding to the difference, and the output signal is used to increase the power of the prime mover via the electro-mechanical conversion means. An automatic speed control method characterized by driving a deceleration mechanism. 2. The automatic speed control method according to claim 1, characterized in that the calculation process of the actual speed is performed by a microcomputer.