JPS58139071A - Indication device for vehicle - Google Patents

Abstract

PURPOSE:To improve the correctness in the computation of revolutions by calculating the revolutions per unit time from a total time of the cycles of the integral number of rotary pulses and the number thereof. CONSTITUTION:Rotary pulse trains 1 being generated are taken into a microcomputer 8 to execute an interrupt routine via a pulse edge detection circuit 11. In the execution of the interrupt routine by a pulse edge time t3, a difference tp-to of pulse edge times is so larger than a fixed time TC that steps 25-29 are executed through a branch 30. Thus, revolutions R are not calculated until a total time of the cycles of the integral number of pulses, namely, the difference of the pulse edge times becomes larger than a certain time. Thus, the revolutions of the integral number of rotary pulse trains can be determined without fail thereby improving the correctness in the calculation of the revolutions.

Description

DETAILED DESCRIPTION OF THE INVENTION In a vehicle such as an automobile, quantities related to rotation information of rotating members, such as vehicle speed due to wheel rotation and engine rotation speed due to crankshaft rotation, are visualized on an instrument panel. The present invention relates to a display device for a vehicle.

In conventional vehicle display devices, in order to display vehicle speed and engine speed, an uneven part is provided on the outer periphery of a rotating disk that rotates in synchronization with the wheels and crankshaft, and the vicinity of the detection part of the electromagnetic pickup is After counting the rotational pulse train that is electrically generated by approaching and passing uneven parts for a certain period of time and converting it to the number of rotations per unit time, or converting it to the vehicle speed if the rotational pulse train is caused by wheels, A method is used in which the information is displayed on a display element in the instrument panel. Further, in addition to the above-mentioned pulse processing method of counting the number of pulses included within a certain period of time, a method of calculating the rotational speed and vehicle speed from the periodic measurement of one pulse is also used.

However, in such conventional pulse processing methods for vehicle display devices, in the case of a method that counts the number of pulses included in a certain period of time, the number of pulses can only be expressed as an integer, and in reality, the number of pulses can be expressed as an integer. Since the number of rotations is large, there will be an error of up to one cycle, and when the rotation is fast and the number of pulses included in a certain period of time is large, K is the calculation of the number of rotations - The difference is small, but when the rotation is slow and the number of pulses included in a certain period of time is calculated. When the number of rotations is small, the calculation error of the rotational speed cannot be ignored.

On the other hand, in the case of the method of measuring one pulse period, each pulse period is not necessarily constant even during constant speed rotation due to machining errors in the uneven parts of the rotating disk. The calculation value of the rotation speed by period measurement is not constant and has the disadvantage that it contains errors.

The present invention has been made to eliminate such drawbacks, and an object of the present invention is to provide a vehicle display device that accurately calculates and displays information regarding the rotation of vehicle members. Hereinafter, this invention will be explained with reference to the drawings.

FIG. 1 is a time chart of a rotation pulse train showing an embodiment of the present invention. In this figure, 1 is a rotating pulse train, 1m to 1c are pulse rising edges, and 2 is a time axis (
t), 2m or 2c is the pulse edge time (1° or 4)% 3 is a predetermined fixed time (Tc)
It is.

FIG. 2 is a block diagram showing an embodiment of the present invention. In this figure, 4 is a rotating disk, which rotates around a rotation center 4 in synchronization with the rotation of wheels (not shown), has four concave portions 4b and four convex portions 4C, and is magnetized. made of magnetic material. 5 is a reed switch, and the convex portion 4C of the rotating disk 4
When K is close, the contact 5m and the convex part 4C constitute a magnetic path, and when the contact 5m is closed and the convex part 4C is more than a certain distance away from the contact 5m, the above magnetic path constitutes K. Therefore, the contact 5m has an opening function. 6 is the grounding point, 1
8 is a signal line of the rotational pulse train 1 that is continuously generated by the contact opening/closing operation of the reed switch 5; 8 is a microcomputer that processes the rotational pulse train 1 and calculates the vehicle speed;
It has a function of outputting a display signal 10 to the display drive WA S, 11 is a pulse edge detection circuit that detects the rising pulse edge of the rotating pulse train 1 by comparing it with a reference voltage 11m, 12 is a timer that generates a time sound, 13 indicates that the pulse edge detection time Mll has detected a pulse edge. 14 is a pulse edge detection interrupt routine that is executed during the execution of a main routine (not shown) that is being processed by a program stored in an instruction code from K. 14 is a liquid display It is element.

The pulse edge detection interrupt routine 13 is executed at 70-- in FIG.
The operation specified in the chart is carried out, that is, in FIG. 3, 21 is the starting point of interrupt processing, 22 to 2s are each step according to the boogram group stored in the instruction code,
22 is a pulse edge time measuring step that queries the timer 12 of FIG. 2 for the pulse edge time and stores the time sound in a memory (not shown); 23 is a memory (not shown)
A pulse counting step of counting and storing the number of pulses as N,+1 by incrementing the content of the stored pulse number N, by @l''; 24 is the pulse edge time t stored in the memory; When the pulse edge time difference t, -'t, formed with the reference pulse edge time 1° (stored in a memory not shown) in the figure becomes larger than a certain time Tc, the branch 30 is selected,
When it is small, a certain time Tc step is selected for branching branch 31, and 25 is the rotation speed R1 from the pulse edge time difference 1p-10 and the pulse number N, that is, R=N, /(
t, -to), a rotation speed calculation step 26 is this rotation speed RK
In the vehicle speed calculation step, k is a constant determined by the size of the wheel and the number of convex portions 4c of the rotating disk 4 shown in FIG. 2. A display signal output step 21 converts the vehicle speed S into an appropriate signal format and transmits the display signal 10 to, for example, a display drive circuit that drives the liquid display element 14 shown in FIG.
@ is the reference time t used in the constant time comparison step 24 when considering the next interrupt.

The reference time update step 2s is a pulse counting memory clearing step in which the memory N for pulse counting is cleared to zero and the number of pulses is newly counted from time t0 (hereinafter referred to as reference time t). Further, 32 is a connection point of the branch 31, and 33 is a return point for returning to the main routine after the execution of each step 22 to 2s by the program group is completed.

The embodiment of the present invention is constructed as described above, and as shown in FIG. The pulse rising edges 1a to 1C of this rotation/muls train 1 are detected, and during the processing of the main routine being executed in the microcomputer 8, the interrupt routine shown in FIG. 3 is executed.

In FIG. 3, each step 25 according to the program group
- 29 are sequentially executed, and in the pulse edge time measurement step 22, the pulse edge time tp is stored in the memo UK as described above, and then in the pulse counting step 23.
The number of pulses is counted by increasing the rotational speed N in the memory by "1".

In the constant time comparison step 24iC, the pulse edge time difference 1. -1° is compared with the constant time l1lc, and for example, the pulse edge time t, (
When executing the interrupt routine at 2b) or t2(2c) IfC, the pulse edge time difference is 1. -1° is a certain time Tc
Since it is smaller, it passes through the branch 31 and reaches the connection point 32,
As it is, ~(3i! Return through the return point 33) (the main routine: core! Return. In the execution of the interrupt routine at the pulse edge time t3 (2d) in FIG. Since it is larger than 'IQ, it passes through the branch 30 and executes steps 25 to 29. In this way, each step 25 to 29 calculates the number of revolutions and calculates the vehicle speed.

Vehicle speed display output, update of reference pulse edge time,
The reset 7 of the pulse counting memory is executed sequentially, and the process returns to the main routine according to the return point SSK.

Therefore, the number of rotations 8 is calculated only when the total time of each period of an integer number of pulses, that is, the pulse edge time difference t, -t6 becomes greater than a certain time T, so the number of rotations is always an integer number of rotations. The rotation speed of the pulse train is determined, making it possible to calculate the rotation speed more accurately than before.

As explained above, the present invention is capable of calculating the total time of each period of the integer number of rotation pulses when the accounting time of each period of the integer number of rotation pulses becomes larger than a predetermined fixed time. Since the number of revolutions per unit time is calculated from the number of pulses, it is possible to obtain an accurate number of revolutions, which has the effect of displaying the exact number of revolutions or the accurate driving status of the vehicle based on this number of revolutions. There is.

[Brief explanation of the drawing]

Fig. 1 is a time chart of a rotation pulse train for explaining an embodiment of the present invention, Fig. 2 is a block diagram showing an embodiment of the invention, and Fig. 3 is an interrupt routine showing an embodiment of the invention. This is a flowchart. In the figure, 1 is a rotating pulse train, 3 is a fixed time, 4 is a rotating disk, 5 is a reed switch, 8 is a microcomputer,
11 is a display drive circuit, 11 is a pulse edge detection circuit, 12 is a timer, 13 is a pulse edge detection interrupt routine, 14 is a liquid display element, 22 is a pulse edge time measurement step,
23 is a pulse counting step, 24 is a constant time comparison step, 25 is a rotation speed calculation step, 26 is a vehicle speed calculation step, 21 is a display signal output step, 28 is a reference time update step, and 21B is a pulse counting memory clear step. . Note that the same reference numerals in the figures indicate the same or similar parts. Agent Shin Kuzuno (1 other person)

Claims (1)

[Claims] A rotational pulse train generating means for generating a rotational pulse train consisting of an electric signal in response to the rotational speed of a rotating member of a vehicle, and a pulse edge for detecting either a rising or falling pulse edge of the rotational pulse generated by the rotational pulse train generating means. a detection means, a pulse edge time measuring means for measuring the time of the pulse edge of the rotational pulse, a pulse counting means for counting the number of rotational pulses, a total time of each cycle of the integer number of rotational pulses, and a predetermined constant time. fixed time comparison means for comparing the magnitude of the rotation pulses, rotation number calculation means for calculating the number of rotations per unit time from the accounting time of each cycle of the integer number of rotation pulses and the number of pulses, and the number of rotations per unit time. or display means for displaying information representing the operating state of the vehicle calculated based on the rotation speed, and the fixed time comparing means, the total time of each cycle of an integral number of rotation pulses is greater than the fixed time. The means for updating the display value of the display means only when it is determined that Vehicle display device that uses images.