JPS6114010B2 - - 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. The present invention relates to an automatic speed control method suitable for constant speed control of a machine.

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 converted 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 setting switch 5 was being turned on, D-
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 pressure 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 due to the response characteristics of F-V converters, it is not possible to quickly and accurately measure the speed, 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 of a frequency proportional to the speed generated from the speed signal detection means within a certain time To, and
Count the auxiliary pulses with a constant period τ sufficiently smaller than the speed pulse period at the maximum speed from the rise of each speed pulse, and from the speed pulse count result N and the auxiliary pulse count result n at the end of the above constant time To, N+τ/To・(N+1)・n is calculated as a quantity proportional to the actual speed, this calculated value is compared with the value corresponding to the set speed, an output signal corresponding to the difference is generated, and the output signal is used to generate electricity. It is characterized in that the acceleration/deceleration mechanism of the prime mover, such as the throttle valve and control rack, is driven through the mechanical conversion means.

Next, embodiments of the present invention will be described in detail with reference to 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 period sufficiently smaller than the speed pulse period at the maximum speed, and a clock pulse generator 22 that generates a clock pulse with a period sufficiently _longer than the speed pulse period at the minimum speed. The clock pulse generator is equipped with a time generating means, that is, a constant time generator 23, and an auxiliary pulse generating means, that is, an auxiliary pulse generator 24 that generates an auxiliary pulse having a period (τ) sufficiently smaller than the speed pulse period at the maximum speed. The generator 22 provides clock pulses to the generator 23 and the auxiliary pulse generator 24 for a fixed period of time. Furthermore, the start of the fixed time T ₀ is synchronized with the rise of the speed pulse at the start of measurement. Furthermore, as shown in FIG. 2, there is provided a speed pulse counting means, ie, a speed pulse counter 25, for counting the speed pulses within a certain time _T0 , and an auxiliary pulse for counting the auxiliary pulses of a certain period τ from the rising edge of each speed pulse. Using the counting means, that is, the auxiliary pulse counter 26, the speed pulse counting result N and the auxiliary pulse counting result n at the end of the above-mentioned constant time _T0 , approximately calculates N+τ/To・(N+1)・n as a quantity proportional to the actual speed. It is provided with an actual speed calculating means, that is, a speed calculator 27, for calculating the actual speed, and a set speed storage means for storing 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. .

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

As mentioned above, the speed pulse counter 25 is 0 at the rise of the fixed time _T0 , and counts 1, 2...N from the next speed pulse, and continues counting for a fixed time T0.
At the end of T ₀ , the pulse count value N is temporarily held. The auxiliary pulse counter 26 is 0 at the rising edge of each speed pulse, and counts 1, 2, . At the end of T ₀ , 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 Fig. 3, T ₀ =N・T _x +n・τ ……(1), therefore, T _x =T ₀ /N (1-τ/T ₀ n) ...(2), and further, V _x =K/T _x =K・N/T ₀ (1-τ/T ₀ n) ^-1
...(3) (K is a constant).

Equation (3) above is unsuitable for digital calculations because it involves division, so if we set τ/T ₀ << 1 to find an approximate equation so that equation (3) can be calculated using only multiplication, we get the following: .

V _x ≒K・N/T ₀ (1+τ/T ₀ n)...(4) (In equation (4), K/T ₀ and τ/T ₀ are constants) By the way, (3) in equation (4) ) error for the formula is n=0
, but reaches a maximum when n is at its maximum value, and becomes discontinuous near the speed where N·T _x equals T ₀ , which impairs stable control of the vehicle speed. Therefore, the error when n is the maximum value is also 0
In order to do this, instead of the above formula (3), V _x ≒K/T ₀ {N+(N+1)τ/T ₀・n}...(
5) It is easily proven as follows.

In other words, the difference between the above approximate formula (5) and exact formula (3), that is, the error ε, is as follows: ε=K/T ₀ {N+(N+1)τ/T ₀・n} −K・N/T ₀ (1 -τ/T ₀・n) ^-1 =K/T ₀ {N+(N+1)τ/T ₀・n} −K・N/T ₀ {1+(τ/T ₀・n)+(τ/T
₀・n) ² +…} =Kτ/T ₀ ²・n{1−N・τ/T ₀・n/(1−
τ/T ₀・n)} =Kτ/T ₀ ²・n{1−(N+1). τ/T ₀・
n}/(1 −τ/T ₀ ·n) (6), and ε becomes 0 at n=0 and n=T ₀ /(N+1)τ.

Here, n=T ₀ /(N+1)τ is the constant time T ₀
Since this is the maximum value of n within the vehicle speed range in which N vehicle speed pulses are included, it shows that the error ε is 0 when n = 0 and the maximum value, and N・
Even before and after the speed at which T _x becomes equal to T ₀ , that is, the boundary vehicle speed at which N increases or decreases, the measured value changes continuously, and a stable vehicle speed control state is always maintained.

Incidentally, although the above equation (5) appears to include division at first glance, since K/T ₀ and τ/T ₀ are constants and can be set in advance, division is not included as an operation. Furthermore, in order to achieve the vehicle speed control function in an actual device, it is not necessary to know the absolute value of the speed according to equation (5), but it is proportional to the set vehicle speed or actual vehicle speed by calculating N+τ/ _T0・(N+1)・n. Needless to say, it is sufficient to compare them as values.

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 a means such as a reed switch is used 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 magnet installation. 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 speed pulse counting result N and the auxiliary pulse counting result n within a fixed time period _T0 that is sufficiently longer than the speed pulse period, so that an average pulse period can be obtained. Even when such a detection means is used, there is an advantage that stable vehicle speed control can be performed. Note that when τ/T ₀ = 0.001 and N≧5, the error according to equation (5) is less than 0.83% at most, so it is not practical for practical purposes.
There is no problem in calculating using equation (5).

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, the output current is output with a constant amplitude and a energization time rate of 50%. The average current is changed so that the energization time rate decreases or increases depending on whether the difference is positive or negative, and the negative pressure from a negative pressure source 33, for example, an automobile intake manifold is introduced into the current-negative pressure converter 34. This converts the change in current into a change in negative pressure. Furthermore, the change in negative pressure is converted into a change in suction force by the negative pressure-suction force 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 always travel 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. Since 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, the above-mentioned conditions are not necessarily required. Naturally, it is not limited to electro-mechanical conversion means. In addition, for 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 in the same manner 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 having a frequency proportional to the speed of the automobile, generated from a speed signal detection means, that is, a speed signal detector 41, is supplied to a microcomputer 50, and a second The actual speed is calculated in the same manner as explained with reference to the figure, and the output signal is supplied to the current-negative pressure converter 54, thereby simultaneously introducing negative pressure from the negative pressure source 53 and converting the change in current into negative pressure. Convert to change. The output of the 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. ,
To enable a car to always run at 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 processing of 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),
Clear the memory area for vehicle speed pulse count value N and the memory area for auxiliary pulse count value n. Next, in step 104, the presence or absence of a rising edge of the output pulse (speed signal) 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 as the auxiliary pulse count value n is incremented, the memory area of the auxiliary pulse count value n is cleared.On the other hand, if it is determined that there is no pulse rise, step 10 is executed.
6, the memory area of the auxiliary pulse count value n is incremented. Then step 107
, a certain time τ (described later) determined by the program 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 109, it is determined whether or not this switch has been operated.If the switch has not been operated, step 1 is executed.
The process proceeds to step 10, and if the switch is operated, the process proceeds to step 112. In step 110, the contents of the memory area at a preset constant time _T0 are compared with the contents of the memory area at a time T, and T<T0 _.
If so, the process returns to step 104, and if T≧ _T0 , the process proceeds to step 111. In this case, step 1
04 through step 110 directly to step 10
Let the computer processing time for one round back to step 4 be the constant time τ added in step 107 above. In steps 111 and 111', the obtained pulse count values N, n and predetermined times T ₀ and τ
Using the value of , calculate the aforementioned N+τ/T ₀・(N+1)・n as a quantity proportional to the actual speed, and at the same time input this calculated value into the actual speed memory area, set the contents of the set speed memory area. It compares it with a value corresponding to the speed, calculates an output signal according to the difference, and generates a control output. Further, in step 112, 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 the loop that passes from step 104 to step 110 and returns directly from there to step 104, the steps of the program are adjusted by inserting NP instructions so that the program execution time is constant no matter which branch loop is passed. .

As described above, according to the present invention, the calculation of the difference between the value of the quantity proportional to the actual speed and the value corresponding to the set speed and the output of the control signal are all digitally processed. It is an inexpensive and highly reliable automatic speed control method that can improve accuracy and the above-mentioned calculation level can be sufficiently processed by a conventional general-purpose 4-bit microcomputer that is mass-produced and sold. It has a very good effect of being able to provide the following.

[Brief explanation of the drawing]

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, 24... 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, 33,5
3... Negative pressure source, 34, 54... Current-negative pressure converter, 3
5, 55... Negative pressure-suction force converter, 36, 56... Link mechanism, 37, 57... Throttle valve, 40
...Speed signal arithmetic processing device, 50...Microcomputer.

Claims (1)

[Claims] 1. Speed pulses with a frequency proportional to the speed generated from the speed signal detection means are counted within a certain time To, and each auxiliary pulse with a constant period τ sufficiently smaller than the speed pulse period at the maximum speed is counted. Counting from the rising edge of the speed pulse, calculate N+τ/To・(N+1)・n as a quantity proportional to the actual speed from the speed pulse count result N and the auxiliary pulse count result n at the end of the above fixed time To. The calculated value and the value corresponding to the set speed are compared, an output signal corresponding to the difference is generated, and the output signal drives the acceleration/deceleration mechanism of the prime mover via the electric-mechanical conversion means. automatic speed control method. 2. The automatic speed control method according to claim 1, wherein the calculation process of the actual vehicle speed is performed by a microcomputer.