JPS5917257B2 - automatic speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic speed control device, and in particular to an automatic speed control device suitable for controlling the traveling 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 speed control device suitable for constant speed control of a machine.

Various configurations have been considered for automatic speed control devices, especially automatic speed control devices that control the speed of automobiles at a constant level. Fig. 1 shows an example of a conventional automatic speed control device for automobiles. In the system diagram shown, 1 is a speed signal detector that generates a pulse signal with a frequency proportional to the speed;
2 is a speed signal generator that converts the pulse signal input from the speed signal detector 1 into a DC signal voltage proportional to the speed using an F-V1 converter (frequency-voltage converter); 3 is a pulse signal of a constant frequency; A pulse generator 4 generates the pulse signal by turning on the set switch 5, and the pulse generator 4 outputs the pulse signal to a counter 6.
γ is a D-A converter that converts the counting result of the counter 6 into an analog voltage. While the set switch 5 is turned on, the output of the D-A converter 7 and the output of the speed signal generator 2 are compared by the comparator 8, and when both outputs match, the comparator 8 With the output of , the goot circuit 4 closes, stops counting the pulse signals, and causes the counter 6 to memorize the speed at that time. 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 power amplification in step 10, current-negative pressure converter 11
converts the magnitude of the current into the magnitude of the negative pressure from the negative pressure source 12, and further converts the magnitude of the current into the magnitude of the negative pressure from the negative pressure source 12.
4, the throttle valve 15 of the gasoline engine is opened and closed to control the speed of the automobile at a constant level. However, in the above-mentioned conventional system, an F-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. insufficient speed measurement accuracy;
Due to the response characteristics of the 2F-V converter, it has disadvantages such as inability to provide a quick and accurate response, especially when the speed is slow and the speed pulse frequency is low.

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, two constant time generation means, a speed pulse counting means, and an auxiliary pulse having a constant period from the rise of each speed pulse. an auxiliary pulse generating means for generating, an auxiliary pulse counting means, an actual speed calculating means,
It is equipped with a set speed storage means and a speed comparison means for comparing the actual speed and the set speed, and the speed pulse counting means counts the speed pulses within a certain time TO, and at the same time counts the speed pulses at a certain period τ which is sufficiently smaller than the speed pulse period at the maximum speed. The auxiliary pulses of τ are counted from the rising edge of each speed pulse by the auxiliary pulse counting means, and the actual speed is calculated from the speed pulse counting result N and the auxiliary pulse τ counting result n in the period of the above fixed time. This calculated value is compared with the value corresponding to the set speed 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 electrical-mechanical conversion means. It is characterized by driving a speed reduction mechanism such as a throttle valve or a control rack.

Next, embodiments of the present invention will be described in detail with reference to 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 22, a clock pulse generator 22, a clock pulse generator 22, a constant time generator 23, The clock pulse generator 22 is provided with an auxiliary pulse generator 24 that generates auxiliary pulses having a period (τ) sufficiently smaller than the pulse period, and the clock pulse generator 22 supplies clock pulses to the generator 23 and the auxiliary pulse generator 24 for a certain period of time. give. Furthermore, the start of the second constant 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, ie, a speed pulse counter 25, which counts speed pulses within a certain time, and an auxiliary pulse counting means, ie, an auxiliary pulse counter, which counts auxiliary pulses of a certain period τ from the rising edge of each speed pulse. 26, and an actual speed calculation that approximately calculates τ N+-・(N+1)・n as an amount TO proportional to the actual speed from the speed pulse counting result N and the auxiliary pulse counting result n at the end of the above-mentioned fixed time TO. It is provided with a speed calculator 27 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. Ru. Hereinafter, the value calculated as a quantity proportional to the actual speed and the value corresponding to the stored set speed are compared by the speed comparison means, that is, the error calculator 31, but regarding the calculation of the actual speed, This will be explained in more detail based on FIG.

As mentioned above, the speed pulse counter 25 &;
0 at the rising edge of O, and 1,2 from the next speed pulse
, . . . N, and at the end of a certain period of time TO, the counted content N is temporarily held.

Further, the auxiliary pulse counter 26 is 0 at the rising edge of each speed pulse, and is 1, 2, etc. from the next auxiliary pulse.
It continues counting as n, and is reset to 0 every time a speed pulse arrives, and the counted content n is temporarily held at the end of a certain period of time TO. Therefore, the period of the speed pulse is Tx, and the speed of the car is.

Then, as shown in FIG. 3, it becomes, and therefore, is expressed by and further expressed by (K is a constant).

Equation (3) above is unsuitable for digital calculations because it includes division. Therefore, an approximate equation can be obtained by setting τ/TO to 1 so that equation (3) can be calculated using only multiplication, as follows.

(In equation (4), the width of the buttock and the width of the bow are constants.) By the way, the error of equation (4) with respect to equation (3) is 0 when n = 0, but when n is the maximum value, maximum, N
- Stable control of vehicle speed is impaired due to the discontinuity near the speed where Tx equals TO.

Therefore, it is easily proven as follows that in order to set the error to O when n is the maximum value, it is sufficient to use the above equation (3) instead. In other words, the difference between the approximate equation (5) and the exact equation (3), that is, the error ε, is as follows. When n=0 and n=TO/(N+1)τ, ε becomes O.

Here, n = TO / (N + 1) τ is the maximum value of n within the vehicle speed range in which N vehicle speed pulses fall within a certain time TO, so when n = 0 and the maximum value, the error ε is 0. The measured value changes continuously even before and after the speed at which N·Tx becomes equal to TO, that is, the boundary vehicle speed where N increases or decreases, 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/TO and τ/TO are constants and can be set in advance, division is not included as an operation. In addition, in order to achieve the vehicle speed control device 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 τ N + 〒7・(N+1)・n. Needless to say, it is sufficient to compare the 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 speed pulse period due to changes in vehicle speed. Moreover, the maximum error is suppressed to a sufficiently allowable level within the practical vehicle speed range, which has the great advantage of enabling stable vehicle speed control.

Furthermore, when using a means such as a reed switch to detect the rotation of a multi-polar magnet driven by a speedometer cable as a speed signal detection means, the interval between vehicle speed pulses may vary even at the same vehicle speed due to the accuracy of magnet installation. The pulse interval is not necessarily constant, and a system in which the vehicle speed is calculated by directly measuring the pulse interval using a clock pulse has the disadvantage that a 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 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 addition, T/T. = 0.001, Nx5, the error according to equation (5) is at most 0.83(f) or less, so there is no problem in practical use (even if the calculation is performed using five components).

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 O, 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 source 33, for example, the negative pressure of the inner manifold of an automobile, is introduced to convert the current 7 to the negative pressure converter. 34 converts the change in current into a change in negative pressure. Further, the change in negative pressure is converted into a change in suction force by the negative pressure/suction force converter 35, and the change in the negative pressure is converted into a change in suction force via the link mechanism 36. to drive. At this time, if the actual speed is larger than the set speed, the throttle valve 3T is driven L in the direction of decreasing the actual speed, and in the opposite case, the throttle valve 31 is driven in the direction of increasing the actual speed, so that the speed is always kept constant. Allows the vehicle to run at the set speed.
Note that if the set speed is once canceled by brake braking or the like, then the set speed can be reset to the desired speed by pressing the set switch 2.
Any value can be stored by pressing 8. In the embodiment described above, the electrical-mechanical conversion means linked to the output signal generator 32 include the negative pressure source 33, the current-negative pressure converter 34, the negative pressure-suction force converter 35, and the link mechanism 3.
Combine 6 and finally throttle valve 3? However, 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 amount of fuel injection by rotating the plunger, if the control rank that rotates the plunger is connected to the link mechanism, it is possible to use a ganolin engine. Good constant speed control can be performed in the same manner as in the case. As mentioned above,
According to this invention, the speed pulse counting result N and the auxiliary pulse counting result n within a certain time TO are counted, and the measured values are continuously obtained even 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 formula that changes, the above-mentioned liquid calculation can be sufficiently processed using a general-purpose 4-bit microcomputer that is mass-produced and sold, and is inexpensive. Moreover, it has an extremely excellent effect in that a highly reliable automatic speed control device can be provided.

[Brief explanation of the drawings] Fig. 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... Cross pulse generator, 23... Fixed time generator, 2
4... Auxiliary pulse generator, 25... Speed pulse counter, 26... Auxiliary pulse counter,
2I... 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 generating means, a speed pulse counting means, and an auxiliary pulse having a fixed period from the rise of each speed pulse. It is equipped with 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, and calculates the speed pulse within a certain period of time ￥T_0￥. At the same time as counting by the pulse counting means, auxiliary pulses with a constant period τ sufficiently smaller than the speed pulse period at the maximum speed are counted from the rising edge of each speed pulse by the auxiliary pulse counting means, and the speed pulse counting result N in the period of the constant time is obtained. From the auxiliary pulse count result n, calculate N+τ/T_0・(N+1)・n as a quantity proportional to the actual speed, compare this calculated value with the value corresponding to the set speed, and output a signal corresponding to the difference. An automatic speed control device characterized in that the output signal drives an acceleration/deceleration mechanism of a prime mover via an electro-mechanical conversion means. 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.