JPS5917258B2 - automatic speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic speed control device, and more particularly to an automatic speed control device suitable for controlling the traveling speed of an automobile to a constant level, and in addition, it relates to an automatic speed control device suitable for controlling the running speed of an automobile to a constant level, and also for a motor vehicle that is subject to severe load fluctuations, such as a stationary motor vehicle. This invention relates to an automatic speed control device suitable for constant speed control of emergency generators.

2. Description of the Related Art Various configurations of automatic speed control devices, particularly automatic speed control devices that control the speed of an automobile to a constant level, have been considered. FIG. 1 is a system diagram showing an example of a conventional automatic speed control device 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 the speed signal detector 1. 3 is a speed signal generator that converts the input pulse signal into a DC signal voltage proportional to the speed using an F-V converter (frequency-voltage converter), and 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 the counter 6 when the set switch 5 is turned on, and T is a DA converter 95 that converts the counting result in the counter 6 into an analog voltage. Then, while adding 5 cents,
The output of the DA converter T and the output of the speed signal generator 2 are compared by the comparator 8, and when both outputs match, the gate circuit 4 is closed by the output of the comparator 8 and the pulse signal is output. Counting is stopped and the speed at that time is stored in the counter 6.
Thereafter, the error amplifier 9 compares and amplifies the difference between the voltage output proportional to the actual speed from the speed signal generator 2 and the output obtained by converting the set speed stored in the counter 6 into an analog voltage. After the power is amplified in step 10, the magnitude of the current is converted into the magnitude of negative pressure from the negative pressure source 12 by the current negative pressure converter 11, and then the current is converted to the negative pressure from the negative pressure source 12 via the negative pressure/suction power converter 13 and the link mechanism 14 to convert the current to the gasoline engine. The speed of the vehicle was controlled at a constant speed by opening and closing the throttle valve 15 of the vehicle. However, in the conventional system described above, an F-V converter is used for the 1-speed signal generator 2, and a D-A converter is used for converting the counting results of the counter 6. It has disadvantages such as insufficient speed measurement accuracy, and the inability to provide a quick and accurate response, especially when the speed is slow and the speed pulse frequency is low, due to the response characteristics of the 2F-V converter. was.

The purpose of this invention is to solve the above-mentioned drawbacks of the prior art,
By digitally processing everything from measuring the actual speed to calculating the difference between the actual speed and the set speed, accuracy can be significantly increased and responsiveness can be achieved, allowing fine-grained speed control to be performed automatically. The object of the present invention is to provide an automatic speed control device that is capable of controlling speed.

The automatic speed control device of the present invention includes a speed signal detection means for generating a speed pulse with a frequency proportional to the speed, a fixed time generation means, a speed pulse counting means, and an auxiliary pulse having a period according to the speed pulse counting result. , an auxiliary pulse counting means, an actual speed calculation means, a set speed storage means, and a speed comparison means for comparing the actual speed and the set speed.

The speed pulses within are counted by a speed pulse counting means, and the speed pulse counting result N and a constant integer N. TokaraT.
The auxiliary pulses generated at a period determined by /(N+1)・NO are counted by the auxiliary pulse counting means, and N+n/NO is determined as the actual speed from the speed pulse counting result N and the auxiliary pulse counting result n at the end of the above fixed time. Approximately calculate the liquid as a proportional quantity, compare this calculated value with the value corresponding to the set speed, generate an output signal corresponding to the difference, and use the output signal to control the prime mover via electrical and mechanical means. It is characterized in that it drives the acceleration/deceleration mechanism, such as the throttle valve and control rack. Next, embodiments of the present invention will be described in detail based on the drawings. FIG. 2 is a system diagram of an automatic speed control device according to an embodiment of the present invention, and particularly shows the case where the automatic speed control device is applied to an automobile equipped with a gasoline engine.

In other words, the automatic speed control device shown in the figure includes a speed signal detection means, that is, a speed signal detector 21, which generates a speed pulse with a frequency proportional to the speed of the vehicle, and a clock pulse with a cycle sufficiently smaller than the speed pulse cycle at the maximum speed. A clock pulse generator 22, a clock pulse generator 22, a clock pulse generator 22, a clock pulse generator 22, a clock pulse generator 23, a clock pulse generator 23, a clock pulse generator 23, a clock pulse generator 23, a clock pulse generator 23, a clock pulse generator 23, a clock pulse generator 23, a clock pulse generator 23, and a clock pulse generator 23 that generates a constant time (TO) that is sufficiently longer than the speed pulse period at the lowest speed. The clock pulse generator 22 is provided with an auxiliary pulse generator 24 that generates an auxiliary pulse with a cycle corresponding to the period of the clock pulse generator 23.
and provides clock pulses to auxiliary pulse generator 24. Further, the start of the fixed time TO is synchronized with the rise of the speed pulse at the start of measurement. Further, the above device includes a speed pulse counting means, that is, a speed pulse counter 25 that counts speed pulses within a fixed time, and an auxiliary pulse that counts auxiliary pulses of a period corresponding to the count contents of the speed pulse counter 25. Counting means or auxiliary pulse counter 26
and an actual speed calculating means, ie, a speed calculator 27, which approximately calculates N+n/NO as a quantity proportional to the actual speed from the speed pulse counting result N and the auxiliary pulse counting result n at the end of the fixed time TO. , and 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. 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 is O at the rise of TO for a certain period of time, and is 1, 2, . . . from the next speed pulse.
・Count as N, and at the end of TO for a certain period of time, the count content N
to be held temporarily. Further, the auxiliary pulse generator 24 is
In accordance with the count N of the speed pulse counter 25 and in synchronization with the rising edge of the speed pulse, an auxiliary pulse having a period determined by the following equation (1) is generated. Note that in equation (1), NO is an i-constant integer, for example, 16.

Further, the auxiliary pulse counter 26 is O at the rising edge of each speed pulse and is 1, 2, . . . from the next auxiliary pulse.
・Count n and wait for a certain period of time T.

At the end of , the count content n is temporarily held. Therefore, if the period of the speed pulse is Tx and the speed of the vehicle is Vx, the following is obtained as shown in FIG.

Therefore, we get moreover, is obtained, and the speed Vx is determined.

By the way, the above formula (4) is not suitable for digital calculations because it includes division, so it can be calculated using only multiplication.
The approximate formula is found as follows.

Therefore, if ε is the error in the speed Vx determined by the approximate expression (5) with respect to the exact expression (4), then ε becomes 0 when n=O and n=NO.

Among these, n = NO is the maximum value of n within the vehicle speed range in which N vehicle speed pulses fall within a certain period of time TO from equation (1), so the speed at which NO - Tx becomes equal to TO, that is, N is The error becomes 0 at boundary vehicle speeds that increase or decrease, and the measured value changes continuously even before and after such vehicle speeds, and a stable vehicle speed control state is always maintained. Here, NO=16
It can be easily proven using equations (4) and (6) that the ratio of the error to the exact value when N≧5 is maximum when N-8, but even if the ratio is 0. It is 83% or less, and there is no problem in practical calculation using equation (5).

By the way, although equation (5) seems to include division at first glance,
Since K/TO and 1/NO are constants, they can be set in advance, and the operations do not include division.

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 vehicle speed according to equation (5), and N+
Needless to say, n/NO may be calculated and compared as a value proportional to the set vehicle speed or the actual vehicle speed. Furthermore, this approximation formula is devised so that the error of the approximation formula relative to the exact formula is 01, that is, the measured value changes continuously, even at the boundary where N increases or decreases (±1) due to changes in the speed pulse period due to changes in vehicle speed. Moreover, there is a great advantage that the maximum error is suppressed to a sufficiently permissible level within the practical vehicle speed range, 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 interval between vehicle speed pulses may not necessarily be the same even at the same vehicle speed due to the mounting accuracy of the magnet. However, 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 certain time TO which 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. 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 an energization time rate of 50 cm is output. The average current is changed so that the energization time rate decreases or increases depending on the positive or negative of the difference, and the negative pressure of a negative pressure source 33, for example, an automobile intake manifold is introduced to convert the current 7 to the negative pressure converter 34. This converts the change in current into a change in negative pressure. Furthermore, the change in the negative pressure is converted into a change in suction force by the negative pressure-suction force converter 35,
Throttle valve 3T is driven via link mechanism 36. At this time, if the actual speed is greater than the set speed, the throttle valve 3? drive,
In the opposite case, throttle valve 3 is moved in the direction of increasing the actual speed.
? By driving the vehicle, the vehicle can always travel at a constant set speed. In the above-described embodiment, the set speed can be stored at an arbitrary value by pressing the set switch 28 again at the desired speed after being canceled by braking or the like. As electrical-mechanical conversion means linked to the signal generator 32, a negative pressure source 33, a current-negative pressure converter 34, a negative pressure-suction force converter 35,
Although the link mechanism 36 is combined to finally drive the throttle valve 37, it is of course not limited to the electro-mechanical conversion means as described above. 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 cook 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. As described above, according to the present invention, the vehicle speed pulse count result N and the auxiliary pulse count result n within a certain time TO are counted, and the measured value is also measured before and after the boundary speed, which does not include division and where N increases or decreases due to changes in vehicle speed. Since the vehicle speed is calculated using an approximation equation in which Therefore, it is possible to provide an automatic speed control device that is inexpensive and highly reliable. In addition, the highest value of the count content n of the auxiliary pulse is
Since it can be kept to a constant relatively small integer NO, it has an advantage that a small number of bits of the counting means is sufficient, and has very excellent effects.

[Brief explanation of drawings]

Figure 1 is a system diagram showing an example of a conventional automatic speed control device.
FIG. 2 is a system diagram of an automatic speed control device according to an embodiment of the present invention, and FIG. 3 is an explanatory diagram showing the synchronization relationship between speed pulses and auxiliary pulses. 21... 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, 30...Speed memory, 31...Error calculator , 32...
Output signal generator.

Claims (1)

[Scope of Claims] 1. A speed signal detection means for generating a speed pulse with a frequency proportional to the speed, a fixed time generation means, a speed pulse counting means, and an auxiliary pulse having a period according to the speed pulse counting result. The device includes an auxiliary pulse generation means, an auxiliary pulse counting means, an actual speed calculation means, a set speed storage means, and a speed comparison means for comparing the actual speed and the set speed. While counting by the counting means, the speed pulse counting result N and a constant integer n_
0, the auxiliary pulses generated at a period determined by T_0/(N+1)・n_0 are counted by the auxiliary pulse counting means, and the speed pulse counting result N and the auxiliary pulse counting result n at the end of the above-mentioned fixed time are N+n/n_0. is approximately calculated as a quantity proportional to the actual speed, this calculated value is compared with a value corresponding to the set speed, an output signal corresponding to the difference is generated, and the output signal is used to convert the electro-mechanical conversion means. An automatic speed control device characterized by driving an acceleration/deceleration mechanism of a prime mover via a. 2. The automatic speed control device according to claim 1, wherein the acceleration/deceleration mechanism of the prime mover is a throttle valve of a gasoline engine. 3. The automatic speed control device according to claim 1, wherein the acceleration/deceleration mechanism of the prime mover is a control rack of a diesel engine.