FR2695483A1 - Device for detecting the pulse rate of a signal for controlling an internal combustion engine. - Google Patents

Abstract

a) Device for detecting the pulse rate of a signal, b) Device characterized in that during a first phase (S1) a first counting means (110; 130) passes through repeatedly with a given counting frequency ( FT) its counting range, and the number of counting ranges thus traversed is detected in a second counting means (140; 120), and in that, during the next phase change of the signal (S1) the final value reached of the second counting means (120; 140) is repeatedly counted down and the final value of these counting processes is available as a measure of the pulse rate. c) The invention relates to devices for detecting the pulse rate of a signal.

Description

"Device for detecting the pulse rate of a signal to control

  The invention relates to a device for the detection, by means of counting processes, of the pulse rate of a signal comprising at least two phases.

its different.

  Devices are known in which

  for measuring the pulse rate of a periodic signal

  This counter counts the duration of the high level of the signal with a known counting frequency. If the duration of the period of the signal is known, the state of the counter is directly proportional to the pulse rate. Yes

  the duration of the period is not known, so

  sure, either with the same meter or with another

  counter, which is also synchronized with the frequency

  known counting period, the time during which the signal level is low or the total duration of the period The pulse rate must then be determined by a division which is performed, for example in a microcomputer A side of the expense necessary for this division, there is, in this case,

  an undesirable delay The pulse rate is not

  possible as soon as possible after the lapse of time

calculation.

  The object of the invention is to create a device

  tif of the type initially mentioned for detecting the pulse rate of a signal, which device is

  of a simple construction and which makes the rate of

  impulses available as much as possible without delay. This object is achieved, thanks to the invention, in that during a first phase a first counting means travels repeatedly with a frequency

  of counting given its counting range, and the

  counting areas thus covered is de-

  tected in a second counting means, and in that

  during the next phase change of the signal the

  their reached end of the second counting means is repetitively counted and the final value of these counting processes is available as

measuring the pulse rate.

  The device according to the invention allows a direct measurement of the pulse rate of a signal of a

  duration of unknown period and possibly even

  without delay In accordance with the inven-

  during a first phase, a first means of

  counting, with a given counting frequency,

  repetitively runs its counting range The number of these counting ranges thus traversed is detected in a second counting means.

  phase change following the signal, the ter-

  of the counting means is again counted and the terminal value of these counting processes gives

  a measure for the pulse rate.

  The device according to the invention is constituted

  killed by a multistage counting means, which comprises at least one counting means capable of

  to be programmed and a second means of counting,

  while at a pre-defined moment, the content of the se-

  cond means of counting takes a value indicating the

  pulse rate This content serves as an indi-

diquering the pulse rate.

  This established signal is available without delay. Advantageous and adequate embodiments, as well as complements of the device, are characterized in that: When a first signal edge appears, a programmable counting means and the second

  counting means are respectively set at a

  during the appearance of a second flank of the

  In general, the programmable counting means stores the

  content of the second counting means while this

  the counting means is reset, with the given counting frequency, the contents of the programmable counting means are changed, the content of the second counting means is changed when the contents of the programmable counting means reaches a value of

predefined value.

  When a first signal edge appears, the first counting means and a third counting means are reset, when a second signal edge appears, a means of signaling.

  programmable count stores the contents of the third

  second counting means, while the second counting means is reset, with the given counting frequency, the contents of the first means of counting.

  counting and the content of the programmable counting means.

  are modified, the content of the third counting means is modified when the content of the first counting means reaches a predefined value, the

  content of the second counting medium is changed when

  that the contents of the programmable counting means

reaches a predefined value.

  The counting frequency given is notable-

  higher than the signal frequency.

  The invention will be explained in more detail

  hereinafter with the aid of the embodiment

  FIG. 1 is a block diagram of the device according to the invention, FIG. 2 shows different signals and counting states of the device according to the invention, FIG. 3 is a block diagram of FIG. another embodiment of the device according to the invention, FIG. 4 shows different signals and

  counting states of this other embodiment.

  The device according to the invention is of

  used for the control of a combustion engine

  When ordering a combustion engine

  internal bustion, especially when determining the control signals for the supply of units

  command to influence power, it is important to

  that the signal pulse rate determined

  be available as quickly as possible.

  A signal generation unit 100 deli-

  A pulse-width modulated signal Si, which is applied to the device according to the invention, 108 This device for the determination of the pulse rate 108 delivers to a control device 106 a signal

  which corresponds to the pulse rate of the signal Si.

  Moreover, the device 108 receives from a clock generator 104 a signal with a frequency

  In a form of realizing

  In a preferred embodiment, the clock generator 104 is included in the device 108 or in the device of FIG.

order 106.

  In the case of the production unit of

  For example, it may be a detector

  delivers a signal corresponding to a characteristic magnitude

  Such a great quantity of

  operating feature can, for example,

  be the end of combustion, the beginning of

  the beginning of the injection or the end of the injection

  In the case of the production unit of

  100, it may also be another

  a control apparatus which outputs a pulse width modulated signal for the control of a unit

  If the control device 106 is

  requiring a signal that corresponds to the pulse rate of the signal Si, then the pulse rate

  signal must be determined by device 108.

  This device 108 for determining the rate of im-

  pulses is then constituted as follows.

  The signal Si to be analyzed is applied to a reset input 112 of a first counter 110, to a reset input

  122 of a third counter 120, at the charge input-

  138 of a programmable counter 130 and an input 142 of a second counter 140 The clock generator 104 delivers a signal FT of a frequency

  very high The counting frequency FT is

  higher than the frequency of the signal Sl Preferably, the counting frequency is higher

  by a factor of 10 to the signal frequency Si at

  ter, for the highest speed of rotation

  This counting frequency FT is applied to an input 114 of the first counter 110 and to an input

134 of the programmable counter 130.

  The output 116 of the first counter 110 delimits

  a signal 52 at the input 124 of the third counter

  The third counter 120 delivers, via

  From its output 226, a signal 53 to the input 132 of the programmable counter 130 The programmable counter delivers, via its output 136, a fourth signal 54 to the input 144 of the second counter

  At the exit of the second counter 140 there is the

  the fourth signal 55 which is applied to the control device 106. The operating mode of this device will be exposed using the evolutions of the signals and

  content (counting status) of the different

  tors, which are shown in Figure 2 On the

  Figure 2 are plotted as a function of time t, the

  If, whose pulse rate is to be calculated, the content Il of the first counter 110, the content I 2

  programmable counter 130, the content I 3 of the third

  second counter 120 and the content 14 of the second counter 140 is further reported, the frequency of

FT counting.

  The signal SI comprises a succession of

  at least two phases, one of the phases comprising a

  signal and the other phase a low signal level. In Figure 2, such a signal is reported to

  As an example It was proceeded in the following

  a slicing for which the signal SI present in the first phase, from the instant O up to

  moment tl, a high level This phase is

  ignited by Tl The second phase of duration T 2 between the in-

  stant t1 and the instant t 2 has a low signal level. The time interval between the instant O and the instant t 2, which corresponds to the sum of the durations Tl

  and T 2, is called duration of the period The report

  Tl and T 2 is usually called the impulse rate.

sions.

  At the moment O at the appearance of the first

  If the signal SI has a rising edge, which means that the signal goes up from a low level to a high level, the first counter 110 is reset by means of its reset input. the initial state 112 At predefined time intervals, i.e. for each pulse of the clock generator 104, the content Il is increased by one. In the case of the first counter, it is 'an N-bit counter It goes through counting states from zero up to 2 N-1 Each overrun of

  first counter 110 is counted by the third count

  120 For this purpose, output 116 of the first

  110 is in connection with entry 124 of the third

counter 120.

  The first counter 110 repeatedly traverses its counting range with the counting frequency defined. The number of counting extents thus traversed is detected by the third counter 120.

  The content 13 of the third counter 120 par-

  The counter 120 then counts at each second Nth pulses the counting frequency. This continues until, at instant t, there is a falling flank. on the signal Si that means that the

  signal IF falls from a high signal level to a

  In this phase change of the signal S1, the first counter 110 is again reset by means of its input.

  restoring 112 Content 13 of the third

  my counter is stored in the program counter.

  This means that this programmable counter is set to this value each time it is exceeded or during each return to the initial state of the counter. Next, the third counter 120 is delivered.

in the initial state.

  As long as the signal Si has a level

  the counters 110 and 120 remain at the zeros

  However, it can also be expected that the two counters continue to scan the predefined counting states. These signals are not necessary for later operation. From time t1, the content I 2 of the programmable counter 130 is reduced by one for each

  pulse of the counting frequency

  the programmable counter 130 is respectively

  It is thus reset periodically on M It thus periodically traverses the counting states from M to one. For each exceeding of the programmable counter 130, the content 14 of the second counter is increased by one when the second side of the signal Si appears. , which in Figure 2 is the falling flank, the contents of the second

  counter 140 is given through its output.

tie 146.

  At time t i, the content I 3 of the third counter 120 corresponds to the value M = INT (FT *

  T1 / 2 N) At time t 2, the second counter 140 presents

  the content E = (FT * T 2 / M) For an appropriate choice of the counting frequency, then E = (2 N * T 2 / T 1) The counting frequency must be chosen from

  significantly greater than the frequency

  the highest intervening factor for the signal If to be analyzed At time t 2, after a period of time, the content I 4 of the second counter is proportional to the

pulse rate T 2 / Tl.

  A particularly advantageous embodiment is shown in FIG. 3. In this embodiment it is provided that the first counter 110 and the third counter 120 are deleted. In this case, the programmable counter 130 supports the missions of the first counter 110 and the second counter. counter 140 supports third counter missions

  The signal generation unit 100 is directly

  The input 132 of the programmable counter 130 is, on the other hand, connected to the output of the second counter 140. The corresponding counting states are connected to the reset input and to the loading input 138 of the programmable counter. and the corresponding signal evolutions are represented

  in FIG. 4 When a positive side appears

  tif on the signal Si, the programmable counter 110 is

  set to the preset count value 2 N and the

  140 for the value O For each pulse of the counting frequency, the content I 2 is decreased by

  In the time interval T1, the counter

  grammable 130 periodically traverses the states of

  counting of 2 N to one For each exceeding of

  programmable controller 130, the content I 4 of the second

140 is increased by one.

  When the falling flank appears in the signal Si, the count state I 4 reaches in the

  second counter 140 is then stored in the

  In the time interval T 2, it is then proceeded correspondingly to the

  previously described embodiment.

  The device according to the invention can be

  realized, with an appropriate hardware circuit

  requested, that also by means of a calculator in combination

  naison with an appropriate program flow.

Claims (5)

  1. Device for detecting, by means of counting processes, the pulse rate of a   signal (Si) comprising at least two different phases   (Tl, T 2), characterized in that, while   first phase (Tl), a first means of computation   (110; 130) travels repeatedly with a   given counting frequency (FT) its range of   floor, and the number of counting areas thus   run is detected in a second counting means (140; 120); and in that, at the next phase change of the signal (SI), the final value reached (M) of the second counting means (120; 140) is repetitively counted and the final value (E) of these   Counting process is available as measurements. re of the pulse rate.   2. Device according to claim 1,   characterized in that: upon the occurrence of a first signal edge (51), a programmable counting means (130) and the second counting means (140) are respectively set to a value, upon occurrence a second side of the signal   (SI), the programmable counting means (130)   gasine the content (I 4) of the second counting means (140) while this second counting means (140) is reset, with the given counting frequency, the contents of the programmable counting means (130) is modified, the content (I 4) of the second counting means (140) is modified when the content (II) of the means of   programmable count (130) reaches a pre-determined value defined.   3. Device according to claim 1,   characterized in that: at the appearance of a first signal flank   (Si) the first counting means (110) and a third   second counting means (120) are reset when a second signal edge appears   (Si) programmable counting means (130)   sine the content (I 3) of the third counting means (120), while the second counting means (140) is reset, with the frequency of the count given, the content   (II) of the first counting means (110) and the   the programmable counting means (130) are   the content (I 3) of the third counting means (120) is modified when the content (II) of the first counting means (110) reaches a predefined value, the content (I 4) of the second counting means (140) ) is amended when the content (I 2) of the means of   programmable count (130) reaches a pre-determined value defined.   4. Device according to any one of   claims 1 to 3, characterized in that the provision   The control system is used to control an engine internal combustion.   5 Device according to any one of   Claims 1 to 4, characterized in that the frequency   given count (FT) is significantly higher   higher than the signal frequency (51).