CN101738211B - Device and method for measuring rotation angle of engine crankshaft - Google Patents
Device and method for measuring rotation angle of engine crankshaft Download PDFInfo
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- CN101738211B CN101738211B CN 200810227084 CN200810227084A CN101738211B CN 101738211 B CN101738211 B CN 101738211B CN 200810227084 CN200810227084 CN 200810227084 CN 200810227084 A CN200810227084 A CN 200810227084A CN 101738211 B CN101738211 B CN 101738211B
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Abstract
The invention discloses a device for measuring the rotation angle of an engine crankshaft, which comprises an encoding disk, a photoelectric sensor, a signal collector and a signal processor, wherein the encoding disk rotates along with the engine crankshaft and produces optical pulse signals; the photoelectric sensor is used for sensing the optical pulse signals which are produced during the rotation process of the encoding disk along with the engine crankshaft and converting the optical pulse signals to electric pulse signals; the signal collector is used for collecting the number of high and/or low level pulses of the electric pulse signals; and the signal processor is used for obtaining the rotation angle of the engine crankshaft according to the number of high and/or low level pulses. The invention can provide the high-precision measurement of the rotation angle of the engine crankshaft. The invention further discloses a method for measuring the rotation angle of the engine crankshaft.
Description
Technical field
The present invention relates to measuring technique, relate in particular to a kind of measurement mechanism and method of engine crankshaft corner.
Background technology
Along with the development of automotive engineering and the raising of discharging standards, more and more higher to the control requirement of engine, realize the accurate control to engine, at first just must realize accurate measurement and the collection of the various data of engine.In numerous data of engine, its crank angle is exactly important data.
The crank angle of engine be by bent axle in the process that rotates a circle the angle corresponding to diverse location of process determine, obtain corresponding piston position by crank angle, thereby determine the duration of ignition of engine.Whether correctly be directly connected to the power output of engine and the combustion case (whether up to standardly discharging) of fuel the duration of ignition of engine.The main harm that bring when incorrect the duration of ignition of engine has: 1, too early then can cause pinking the duration of ignition of engine, thereby damage engine or reduce its life-span.If too late then can make that oil inflame is insufficient just to be discharged from, cause atmospheric pollution the duration of ignition of 2 engines, thereby make serious not up to standard of discharging.3, be the power output deficiency that shifts to an earlier date or all can make too late engine the duration of ignition of engine.
At present, crank angle pick-up unit commonly used is electromagnetic sensor, and the fluted disc of certain number of teeth namely is installed at bent axle one end of engine, and then electromagnetic induction element (for example Hall element) is fixedly mounted on certain position with respect to fluted disc.Like this, when engine rotation, the teeth that are installed on the fluted disc of bent axle one end will be successively near electromagnetic induction element, thereby produces the sinusoidal wave waveform that is similar to of the corresponding number of teeth at the signal output part of electromagnetic induction element.The output waveform of this electromagnetic sensor is differential signal, makes it become the square wave with same frequency by conversion process, therefore determines the crankshaft rotating particular location in one week according to these square waves.
But existing electromagnetic sensor has following shortcoming: the number of teeth of (1) fluted disc is less, and the precision of sensor is lower; (2) waveform of the generation of electromagnetic sensor is subjected to the impact of rotating speed very large, and the crest value of the voltage signal that produces when low speed and high speed alters a great deal, and approximate waveform contrasts as shown in Figure 3.As shown in the figure, voltage very little (generally only having several volts) during low speed, and voltage just very large (can reach tens volts) during high speed, the voltge surge to the chip of processing this signal is just very large like this, causes the very major injury to chip; (3) in the process of carrying out the square wave conversion, can cause the pulsewidths of square wave different with the different amplitudes differences that produce of rotating speed height because of sensor, thereby produce error, the test error that causes sensors with auxiliary electrode were to produce is larger; (4) installation requirement of sensors with auxiliary electrode were is higher, refer to that mainly the relative position of fluted disc and electromagnetic induction element must be the same large, otherwise the error of the waveform that produces will be larger.
Therefore, the engine crankshaft corner measurement mechanism of prior art can not provide accurate outer corner measurement.
Summary of the invention
Purpose of the present invention is intended to one of solve the aforementioned problems in the prior at least.
For this reason, the present invention proposes a kind of measuring method and device of engine crankshaft corner, thereby provides accurate crank angle to measure.
According to one aspect of the invention, the measurement mechanism of the engine crankshaft corner that the embodiment of the invention provides comprises: code-wheel, rotate and produce light pulse signal with engine crankshaft; Photoelectric sensor is used for responding to the light pulse signal that described code-wheel produces with the engine crankshaft rotary course, and described light pulse signal is converted to electric impulse signal; Signal picker is for the height and/or the low level pulse quantity that gather described electric impulse signal; And signal processor, obtain the angle that engine crankshaft rotates according to described height and/or low level pulse quantity.
According to a further aspect in the invention, embodiments of the invention propose a kind of measuring method of engine crankshaft corner, may further comprise the steps: the code-wheel that rotates with engine crankshaft is set; At described code-wheel in the engine crankshaft rotary course, to described code-wheel emission of light to produce light pulse signal; Gather described light pulse signal and be converted to electric impulse signal; Height and/or the low level pulse quantity of described electric impulse signal are counted; With the anglec of rotation according to described height and/or low level pulse counting acquisition engine crankshaft.
The present invention is applied to photoelectric sensor and photoelectric coded disk in the outer corner measurement of engine crankshaft, can greatly improve the measuring accuracy of corner, thereby for foundation accurately is provided the duration of ignition of control engine, and improve on the whole the overall performance of engine, reduce discharging pollutants of engine.And the electric impulse signal waveform that photoelectric sensor is not only exported is not subjected to the impact of engine speed, and the voltage magnitude of its waveform remains unchanged when high engine speeds and low speed.Can avoid like this voltge surge to the chip of processing photo-sensor signal will, improve the reliability of whole measurement mechanism.
The aspect that the present invention adds and advantage in the following description part provide, and part will become obviously from the following description, or recognize by practice of the present invention.
Description of drawings
Above-mentioned and/or additional aspect of the present invention and advantage are from obviously and easily understanding becoming the description of embodiment below in conjunction with accompanying drawing, wherein:
Fig. 1 is the block diagram of the engine crankshaft corner measurement mechanism of the embodiment of the invention;
Fig. 2 is the code-wheel of the embodiment of the invention and mounting structure vertical view and the front elevation of photoelectric sensor;
Fig. 3 is the electric impulse signal oscillogram example of photoelectric sensor output of the present invention;
Fig. 4 is the electric impulse signal process waveform transformation of photoelectric sensor output of the present invention and the oscillogram example after the amplification;
Fig. 5 is engine crankshaft corner measuring method flow chart of steps of the present invention; With
Fig. 6 is the flow chart of steps in conjunction with pulsewidth timing acquisition crank angle of the embodiment of the invention.
Embodiment
The below describes embodiments of the invention in detail, and the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or the element with identical or similar functions from start to finish.Be exemplary below by the embodiment that is described with reference to the drawings, only be used for explaining the present invention, and can not be interpreted as limitation of the present invention.
At first, please refer to Fig. 1, this figure is the block diagram of the engine crankshaft corner measurement mechanism of the embodiment of the invention.
As shown in the figure, measurement mechanism of the present invention comprises code-wheel 12, photoelectric sensor 14, signal picker 16 and signal processor 18.Code-wheel 12 rotates with engine crankshaft, and by receiving the light by the light emitters (not shown) emission of photoelectric sensor 14, produces light pulse signal.Photoelectric sensor 14 also comprises the light receiver (not shown), is used for the light pulse signal that received code dish 12 produces.Photoelectric sensor 14 is according to the receiving optical signals of light receiver, the light pulse signal that induction code dish 12 produces in the engine crankshaft rotary course, and light pulse signal is converted to electric impulse signal.
Signal picker 16 is connected with the output terminal of photoelectric sensor 14, thereby the electric impulse signal of photoelectric sensor 14 conversion is gathered, and carries out the high and/or low level pulse number count of electric impulse signal.Signal picker 16 is input to timing result in the signal processor 18,18 angles that obtain the engine crankshaft rotation according to height and/or low level pulse quantity of signal processor.
In addition, signal picker 16 gathers the umber of pulse that engine crankshaft rotates a circle, and namely measuring accuracy is relevant with the resolution of photoelectric sensor 14.For example, when the resolution of photoelectric sensor 14 is 20KHz, the photoelectric sensor 14 that namely adopts is when maximum manageable umber of pulses are 20K in 1 second, if engine crankshaft rotates 100 circles within 1 second, in the process of crankshaft rotating one circle, the corner pulse that photoelectric sensor 14 can be processed at most bent axle output is 200 so.That is to say, and in the process that rotates a circle together of engine crankshaft, the optical signal pulses that code-wheel 12 produces can reach at most 200.Therefore, in the situation that engine peak speed is certain, the resolution of photoelectric sensor 14 is higher, and crank angle corresponding to each optical signal pulses is less, so just can greatly improve the measuring accuracy of crank angle.But, because the data-handling capacity of signal picker 16 is limited, thus measuring accuracy can not arrange too high.In actual applications, the resolution of photoelectric sensor 14 can be processed based on signal picker 16 the suitable size of quantity setting of electric impulse signal.
The mounting structure figure of code-wheel 12 and photoelectric sensor 14 as shown in Figure 2, Fig. 2 is from overlooking and positive angle is showing a kind of installation configuration relation embodiment of code-wheel 12 and photoelectric sensor 14.As shown in the figure, on the code-wheel 12 evenly annular be provided with alternate each other bright line coding scale g1 and dark line coding scale g2, bright line coding scale g1 and dark line coding scale g2 are used for respectively stopping or emitting beam by light emitters.The optical axis center of photoelectric sensor 14 (h represents the center line of optical axis among Fig. 2) is corresponding with the center pit of coding scale g1, g2, thereby code-wheel 12 can receive more delicately light and produce accurate light pulse signal.
The embodiment that it is pointed out that Fig. 2 only is used for the example purpose, does not lie in restriction the present invention.For example, code-wheel 12 is the coding fluted disc, and its outer rim evenly is provided with teeth and tooth lacks, with the light that is respectively applied to stop or pass through to launch from the light emitters of photoelectric sensor 14.
Now, return with reference to figure 1, be elaborated in connection with the different structure of the code-wheel engine crankshaft corner measurement mechanism to the embodiment of the invention.
To having the code-wheel 12 of bright line shown in Figure 2 and dark line coding scale g1 and g2, in the process of code-wheel 12 and engine crankshaft rotation, the light that the light emitters of photoelectric sensor 14 is transmitted on the code-wheel 12 bright line coding scale g1 can pass therethrough, the light that is transmitted on the dark line coding scale g2 can reflect, and is transferred on the light receiver of photoelectric sensor 14.Therefore, photoelectric sensor 14 is sensed the corresponding light pulse signal that produces of this code-wheel, and converts the crankshaft rotating angular displacement to electric impulse signal by opto-electronic conversion.Here, photoelectric sensor 14 is converted to low level electric impulse signal with the corresponding light pulse signal that produces of dark line coding scale g2, the corresponding light pulse signal that produces of bright line coding scale g1 is converted to the electric impulse signal of high level.
Similarly, the code-wheel 12 that lacks having teeth and tooth, photoelectric sensor 14 is converted to low level electric impulse signal with the light pulse signal of the teeth generation of code-wheel 12, and tooth is lacked the electric impulse signal that the optical signal pulses that produces is converted to high level.
For example shown in the embodiment of Fig. 3, this output electric pulse is approximately rect.p. to the electric impulse signal waveform of photoelectric sensor 14 output.In addition because photo-sensor signal will output waveform voltage is not subjected to the impact of engine crankshaft rotating speed, so its at a high speed and during low speed the voltage magnitude of waveform can remain unchanged.
Signal picker 16 can be according to the electric impulse signal of photoelectric sensor 14 outputs, take single high/low level pulse as unit, respectively successively to high level and low level pulse counting; Perhaps take high level and low level pulse summation as unit, only high level or low level are counted.16 pairs of single high or low level pulse countings of setting signal collector can reduce signal picker 16 and carry out complexity and the processing time that counting is processed.Certainly, the level pulse unit of counting is less, and the anglec of rotation that each count pulse is corresponding is less, and the precision of corresponding outer corner measurement is higher.So the step-by-step counting unit of signal picker 16 can suitably set according to actual needs.
In addition, in one embodiment, crank angle measurement mechanism of the present invention may further include waver 20 and amplifier 22.Shown in Fig. 2 dotted line counterpart, waver 20 is converted to the electric impulse signal of photoelectric sensor 14 outputs the square wave of standard, for example waver 20 is a not circuit, by electric impulse signal being carried out the simple process of not gate, can obtain square wave.Certainly, waver 20 of the present invention is not limited to this specific embodiment, and any equipment that can be used for the square wave conversion all is applicable to the present invention in the prior art.The square-wave voltage that 22 in amplifier is used for further waver 20 being exported amplifies, and for example the electric impulse signal waveform of gained as shown in Figure 4.Square wave by waver 20 outputs, can make things convenient for the accurate metering of 16 pairs of electric impulse signals of signal picker, and the amplification by 20 pairs of square-wave voltage values of amplifier, the intensity voltage value of electric impulse signal is reached in the identification range of the corresponding signal picker 16 that adopts, for example high level is enlarged into 5V, low level is enlarged into 1V, thereby can further improve the signals collecting precision of signal picker 16.
In one embodiment, signal picker 16 can also comprise pulse width timing unit (not shown), and the pulse width timing unit is used for carrying out timing according to the high/low level pulse widths of described electric impulse signal.And, signal processor 18 also comprises pulse width processing unit (not shown), with according to the pulse width timing unit during to the width gauge of high/low level pulse, determine the anglec of rotation of the engine crankshaft that the certain width of single high/low level pulse is corresponding.It is in order further to improve the accuracy of detection of crank angle that pulse width timing unit and pulse width processing unit are set, and satisfy crank angle corresponding to ignition location and be positioned at needs in the middle of two pulses, be to solve when the angle that needs igniting just drops on and can't have realized the accurately problem of igniting between two pulses.
Below, in connection with Fig. 3 and Fig. 4 embodiment, the principle of work of pulse-width timing unit and pulse width processing unit is described as follows respectively.
The width that the pulse width timing unit is used for paired pulses in the pulse number counting of 16 pairs of electric impulse signals of signal picker carries out timing, and the pulse width timing unit is that the width starting point from each high/low level pulse of electric impulse signal begins timing.In one embodiment, for high level pulse, its width starting point is corresponding with the first predetermined threshold voltage on each high level pulse; For low level pulse, its width starting point is corresponding with the second predetermined threshold voltage on each low level pulse.Specifically, the width starting point of high level pulse and terminal point are corresponding respectively with the first predetermined threshold magnitude of voltage of this rising edge of a pulse and negative edge, and the width starting point of low level pulse and terminal point are corresponding respectively with the second predetermined threshold voltage of this pulse negative edge and rising edge.That is to say, the pulse width timing unit can according to the magnitude of voltage point of dividing the high and low level of electric impulse signal, be determined the starting point when it begins width gauge.Because code-wheel evenly is provided with teeth and tooth is scarce or bright, the scale of secretly encoding, in the situation that crankshaft speed variation, the width of their corresponding adjacent high level pulses that produces and low level pulse is still approximately uniform.
The pulse width timing unit continuously timing or with predetermined time the interval carry out timing, and corresponding output timing numerical value is in the pulse width processing unit of signal picker 16.Certainly, the time interval of timing is less, and the pulse width timing unit is higher to the accuracy of timekeeping of current pulse width.Correspondingly.The angle that this timing of pulse width processing unit processes obtains is more accurate.
Electric impulse signal shown in Figure 3 for example, when the pulse width timing unit can begin to carry out a high level pulse width gauge as the width starting point from the corresponding point of the first predetermined threshold voltage 2.4V of rising edge, and when beginning the width gauge of a low level pulse from the corresponding point of the second predetermined threshold voltage 0.4V of negative edge as the width starting point.Like this, by to the pulse width timing between the 2.4V voltage of rising edge and negative edge, can obtain the timing time of certain width and whole width on the corresponding high level pulse.In like manner, can obtain the timing time of certain width and whole width on the corresponding low level pulse.Certainly, the first predetermined threshold voltage of the present invention and the second predetermined threshold voltage are not limited to specific embodiment, when the pulse width timing unit can carry out from the corresponding voltage value point of the high and low level of any division the width gauge of corresponding high level, low level pulse.For electric impulse signal shown in Figure 4, the width starting point of each high and low level pulse is respectively the corresponding point of its rising edge and negative edge.Here, the pulse width timing unit only carries out timing for the width of each current high/low level pulse, if complete to whole pulse width timing, then the width starting point from next level pulse re-starts timing.
Shown in Fig. 3 embodiment, the pulse width timing unit can obtain timing time t1 corresponding to the whole width of single high/low level pulse and adjacent time t2 corresponding to current single high/low level pulse certain width thereof by the pulsewidth timing.The pulse width processing unit is then according to the ratio of the timing time t2 of the current high/low level pulse widths timing time t1 corresponding with the whole width of previous high/low level pulse, calculate their ratio, thereby determine crank angle corresponding to level pulse widths of t2 time according to crank angle corresponding to single high/low level pulse of this ratio and t1 time.Because speed can constantly change during the bent axle actual motion, therefore in order to obtain more accurately crank angle corresponding to current level pulse widths, in embodiments of the present invention, carrying out corresponding corner as the basis take the whole width timing time of the adjacent previous pulse of this current level pulse calculates.
Below, make in conjunction with specific embodiments detailed description.Suppose evenly to be provided with on the code-wheel 12 120 teeth, be that corner corresponding to each teeth is 3 °, and by the code-wheel 12 that this structure arranges, photoelectric sensor 14 outputs and through the electric impulse signal oscillogram of waver 20 and amplifier 22 as shown in Figure 4.0 position is as reference point in Fig. 4, in the process that code-wheel 12 rotates with engine crankshaft, current demand signal collector 16 is for example only counted the high/low level of electric impulse signal, and step-by-step counting is 3, namely have 3 high level pulses or low level pulse, high/low level pulse of every counting represents that the angle that crankshaft rotating is crossed is 3 °.And the width timing time that the pulse width timing unit is worked as prepulse is
T0, the timing time that the whole width of its previous pulse is corresponding is t0.Therefore, the pulse width processing unit ratio that obtains them according to this two width times is
Signal processor 18 is according to 3 current step-by-step countings, crank angle corresponding to single high/low level pulse
, the timing ratio determined of pulse width processing unit
, can determine that the angle that current crankshaft rotating is crossed is
When the angle of measuring is used for engine ignition, if the ignition advance angle of the engine of setting is 10 °, then when bent axle turns over this angular dimension, by signal processor 18 value of taking measurement of an angle of correspondence is sent to control unit of engine (ECU), thereby can begin igniting by control engine at this position ECU.
Certainly, be not limited to this specific embodiment when step-by-step counting of the present invention and width gauge, for example the counting of signal processor can single high and low level pulse be unit, and the pulse width timing unit carries out timing with the width of single level pulse equally, perhaps, count take a high level and low level pulse as unit and the pulse width timing of corresponding unit etc. similar fashion when all being applicable to step-by-step counting of the present invention and width gauge.
In addition, measuring system of the present invention can also comprise display unit, is used for the angle-data that the engine crankshaft that signal processor 18 is exported rotates is shown.
By the measurement mechanism of engine crankshaft corner of the present invention, can accurately measure the angle that current crankshaft rotating is crossed, thereby can provide accurate corner signal for control unit of engine (ECU), to be used for the duration of ignition of control engine.In addition, the present invention by to the electric signal step-by-step counting time also the width to individual pulse carry out timing, thereby can further improve the precision of outer corner measurement.When the anglec of rotation corresponding to engine ignition position is between two pulses of counting, the step-by-step counting of measuring corner further can be segmented by the pulse width timing, thereby obtain more high-precision measurement corner, and also can obtain accurately measurement data when adopting this mode very large for engine speed fluctuation.
Below, please refer to Fig. 5, this figure is engine crankshaft corner measuring method flow chart of steps of the present invention.
As shown in the figure, the method may further comprise the steps: at first, the code-wheel (step 102) that rotates with engine crankshaft is set.In one embodiment, on the code-wheel evenly annular be provided with alternate each other bright line and dark line coding scale, bright line coding scale and dark line coding scale are used for respectively stopping or passing through light.Perhaps, code-wheel is the coding fluted disc, and its outer rim evenly is provided with teeth and tooth lacks, to be respectively applied to equally stop or pass through light.But it is pointed out that code-wheel of the present invention is not limited to these embodiment, the photoelectric coded disk of any prior art is applicable the present invention all.
Then, at code-wheel in the engine crankshaft rotary course, to the code-wheel emission of light to produce light pulse signal (step 104).For example, to having above-mentioned code-wheel with bright line and dark line coding scale, in the process of code-wheel and engine crankshaft rotation, the light that is transmitted on the bright line coding scale of code-wheel can pass therethrough, and the light that is transmitted on the dark line coding scale can reflect.Similarly, the code-wheel that lacks having teeth and tooth, light lacks transmission from tooth, and is reflected at the teeth place.
Then, the light pulse signal that produces according to code-wheel gathers, and is converted to electric impulse signal (step 106).To the corresponding light pulse signal that produces of code-wheel, thereby convert the crankshaft rotating angular displacement to electric impulse signal by opto-electronic conversion.In one embodiment, the corresponding light pulse signal that produces of the dark line coding of code-wheel scale can be converted to low level electric impulse signal, the corresponding light pulse signal that produces of bright line coding scale be converted to the electric impulse signal of high level.Perhaps, the code-wheel that lacks having teeth and tooth, the light pulse signal that teeth are produced is converted to low level electric impulse signal, and tooth is lacked the electric impulse signal that the optical signal pulses that produces is converted to high level.
Be approximately rect.p. by the opto-electronic conversion output electric pulse, the below then needs according to the electric impulse signal of conversion its level pulse quantity to be counted (step 108).Here, the level pulse number count of electric impulse signal can single high/low level pulse be unit, respectively successively to high level and low level pulse counting; Perhaps take high level and low level summation as unit, only high level or low level are counted.
Then, carry out angular transition according to height and/or low level pulse counting, thereby obtain the anglec of rotation (step 110) of engine crankshaft.Counting and code-wheel corner corresponding to individual pulse counting according to level pulse quantity, for example, when only high/low level pulse being counted, if evenly be provided with the teeth of 120 formed objects on the code-wheel, then to lack corresponding corner be 3 degree for adjacent teeth and tooth, and a corresponding angle corresponding to high/low level pulse counting is 3 degree.Therefore, by number of pulses is changed, thereby can obtain the angle that bent axle has rotated through.
In addition, in one embodiment, can also may further comprise the steps before the electric impulse signal level pulse number count of step 108 carrying out: the electric impulse signal of step 106 output is converted to the square wave of standard, and this square wave is amplified.For example, by electric impulse signal being carried out the simple process of not gate, namely electric impulse signal can be converted to the square wave of standard.Be converted to the electric impulse signal that square wave can be easy to step 108 pair this waveform and carry out accurate metering.Certainly, waveform transformation step of the present invention is not limited to this specific embodiment, and any method that can be used for the square wave conversion all is applicable to the present invention in the prior art.
It is in order to gather discernible scope so that magnitude of voltage corresponding to its high and low level is positioned at level pulse, with the precision of further raising number of pulses counting that square wave is amplified.
In addition, the measuring method of engine crankshaft corner of the present invention can also comprise the step of each pulse width being carried out timing.Carrying out the pulse width timing is in order further to improve the accuracy of detection of crank angle, and satisfy crank angle corresponding to ignition location and be positioned at needs in the middle of two pulses, be to solve when the angle that needs igniting just drops on and can't have realized the accurately problem of igniting between two pulses.
Specific embodiment about this step please refer to Fig. 6, and Fig. 6 is the flow chart of steps in conjunction with pulsewidth timing acquisition crank angle of the embodiment of the invention.
In the high/low level pulse number count to electric impulse signal, begin timing (step 202) from the width starting point of each high/low level pulse of electric impulse signal.But the present invention is not limited to this specific embodiment, and for example the pulsewidth timing also can be an adjacent high level pulse and low level pulse is unit when carrying out width gauge, and certainly, the precision of timing can decrease in this case.
In one embodiment, for high level pulse, its width starting point can be corresponding with the first predetermined threshold voltage on each high level pulse; For low level pulse, its width starting point can be corresponding with the second predetermined threshold voltage on each low level pulse.The width starting point of high level pulse and terminal point are corresponding respectively with the first predetermined threshold magnitude of voltage of this rising edge of a pulse and negative edge, and the width starting point of low level pulse and terminal point are corresponding respectively with the second predetermined threshold voltage of this pulse negative edge and rising edge.That is the starting point in the time of, can determining beginning individual pulse width gauge according to the magnitude of voltage point of dividing the high and low level of electric impulse signal.Because code-wheel evenly is provided with the teeth of formed objects and tooth is scarce or bright, the scale of secretly encoding, in the situation that crankshaft speed variation, their corresponding adjacent high level pulses that produces and the width approximately equal of low level pulse.
Here, for example can be in conjunction with the embodiment of Fig. 3, exemplary illustration is made in the first predetermined threshold voltage and the setting of the second predetermined threshold voltage to electric impulse signal, as shown in Figure 3, the 2.4V that rising edge can be set is the first predetermined threshold voltage, width starting point during with a high level pulse width gauge is corresponding, and the 0.4V that negative edge is set is the second predetermined threshold voltage, and the width starting point during with the width gauge of a low level pulse is corresponding.Like this, by to the pulse width timing between the 2.4V voltage of rising edge and negative edge, can obtain the timing time of certain width and whole width on the corresponding high level pulse.In like manner, can obtain the timing time of certain width and whole width on the corresponding low level pulse.But, it is pointed out that the threshold voltage setting corresponding to width starting point of high and low level pulse of the present invention is not limited to this specific embodiment.For example for Fig. 3, according to the magnitude of voltage that the high and low level of electric impulse signal is divided, the first predetermined threshold voltage and the second predetermined threshold voltage can be arranged on any appropriate voltage location place between 0.4V and the 2.4V.
Therefore, when the first predetermined threshold voltage of the present invention and the second predetermined threshold voltage can carry out the width gauge of corresponding high and low level pulse from the magnitude of voltage point of the high and low level of any division, certainly, when bent axle at the uniform velocity rotated, the pulsewidth of corresponding each high and low level of dividing was identical.For the electric impulse signal through square wave conversion and voltage amplification, the width starting point of each high and low level pulse is respectively the corresponding point of its rising edge and negative edge.
In addition, the pulse width timing can be carried out timing by a width for each current high/low level pulse, if complete to whole pulse width timing, then the width starting point from next level pulse re-starts timing.
Therefore, by the pulsewidth timing, can obtain time t2 (step 204) corresponding to current single high/low level pulse certain width.Timing time t2 can according to current level pulse widths change continuously or with predetermined time the interval carry out timing and output.The time interval of timing is less, and the accuracy of timekeeping of current pulse width is higher.Then, the timing time t1 corresponding with the whole width of previous high/low level pulse according to the timing time t2 of current high/low level pulse widths calculates their ratio t2/t1 (step 206).Timing time t1 is the timing between this previous high/low level pulse widths origin-to-destination.Thereby, according to crank angle corresponding to single high/low level pulse of this ratio and t1 time, can determine crank angle (step 208) corresponding to current level pulse widths of t2 time.
In embodiments of the present invention, carrying out corresponding corner as the basis take the whole width timing time of the adjacent previous pulse of this current level pulse calculates, because speed can constantly change during the bent axle actual motion, but the velocity variations that adjacent two level pulses are corresponding is less, and the width that adjacent two level pulses are corresponding is approximate identical.Therefore in order to obtain more accurately crank angle corresponding to current level pulse widths, the embodiment of the invention utilizes the whole width timing time of previous pulse to calculate the corner of current level pulse widths.
At last, according to corresponding crank angle and crank angle corresponding to current width of high/low level pulse counting, carry out addition and can obtain the current angle (step 210) that rotates through of bent axle.Therefore, when the anglec of rotation corresponding to engine ignition position is between two pulses of counting, the step-by-step counting of measuring corner further can be segmented by the pulse width timing, thereby obtain to measure more accurately corner, and also can obtain accurately measurement data when adopting this mode very large for the engine speed fluctuation.By the measuring method of engine crankshaft corner of the present invention, can accurately measure the angle that current crankshaft rotating is crossed, thereby can provide accurate corner signal for control unit of engine (ECU), to be used for the duration of ignition of control engine.
In addition, measuring method of the present invention can also comprise the step that the angle-data with engine crankshaft rotation shows, with offer the related personnel with in real time, direct measurement data.
Although illustrated and described embodiments of the invention, for the ordinary skill in the art, be appreciated that without departing from the principles and spirit of the present invention and can carry out multiple variation, modification, replacement and modification to these embodiment, scope of the present invention is by claims and be equal to and limit.
Claims (11)
1. the measurement mechanism of an engine crankshaft corner comprises:
Code-wheel rotates and produces light pulse signal with engine crankshaft;
Photoelectric sensor is used for responding to the light pulse signal that described code-wheel produces with the engine crankshaft rotary course, and described light pulse signal is converted to electric impulse signal;
Signal picker is for the height and/or the low level pulse quantity that gather described electric impulse signal; And
Signal processor obtains the angle that engine crankshaft rotates according to described height and/or low level pulse quantity, wherein,
Described signal picker also comprises the pulse width timing unit, described pulse width timing unit is used at signal picker to described electric impulse signal in the high/low level pulse number count, begins timing from the width starting point of described each high/low level pulse of electric impulse signal; And obtain current single time corresponding to high/low level pulse widths; And
Described signal processor also comprises the pulse width processing unit, and described pulse width processing unit is for the ratio of the timing time that the calculates described current high/low level pulse widths timing time corresponding with the whole width of previous high/low level pulse; With determine crank angle corresponding to described current single high/low level pulse widths according to this ratio and crank angle corresponding to single high/low level pulse.
2. measurement mechanism as claimed in claim 1 is characterized in that, described photoelectric sensor comprises:
Light emitters is used for to described code-wheel emission of light to produce described light pulse signal; And
Light receiver is used for receiving described light pulse signal.
3. measurement mechanism as claimed in claim 2, it is characterized in that, the outer rim of described code-wheel evenly is provided with teeth and tooth lacks to be used for stopping or passing through described light, described photoelectric sensor is converted to low level electric impulse signal with the light pulse signal that described teeth produce, and described tooth is lacked the electric impulse signal that the optical signal pulses that produces is converted to high level.
4. measurement mechanism as claimed in claim 2, it is characterized in that, evenly be provided with alternate each other bright line and dark line coding scale on the described code-wheel to be used for stopping or passing through described light, described photoelectric sensor is converted to low level electric impulse signal with the light pulse signal that described dark line coding scale produces, and the light pulse signal of stating clearly line coding scale generation is converted to the electric impulse signal of high level.
5. measurement mechanism as claimed in claim 1, it is characterized in that, also comprise waver and amplifier, described waver is converted to the described electric impulse signal of described photoelectric sensor output the electric impulse signal of square wave, and described amplifier carries out voltage amplification with the described electric impulse signal of square wave.
6. measurement mechanism as claimed in claim 1 is characterized in that, the quantity that the resolution of described photoelectric sensor is processed described electric impulse signal based on described signal picker is set.
7. the measuring method of an engine crankshaft corner is characterized in that, may further comprise the steps:
The code-wheel that setting is rotated with engine crankshaft;
At described code-wheel in the engine crankshaft rotary course, to described code-wheel emission of light to produce light pulse signal;
Gather described light pulse signal and be converted to electric impulse signal;
Height and/or the low level pulse quantity of described electric impulse signal are counted;
In the high/low level pulse number count to described electric impulse signal, begin timing from the width starting point of described each high/low level pulse of electric impulse signal;
Obtain current single time corresponding to high/low level pulse widths;
Calculate the ratio of the timing time of the described current high/low level pulse widths timing time corresponding with the whole width of previous high/low level pulse; With
Determine crank angle corresponding to described current single high/low level pulse widths according to this ratio and crank angle corresponding to single high/low level pulse.
8. measuring method as claimed in claim 7, it is characterized in that, the outer rim of described code-wheel evenly is provided with teeth and tooth lacks to be used for stopping or passing through described light, the light pulse signal that in described electric impulse signal switch process described teeth is produced is converted to low level electric impulse signal, and described tooth is lacked the electric impulse signal that the light pulse signal that produces is converted to high level.
9. measuring method as claimed in claim 7, it is characterized in that, evenly be provided with alternate each other bright line and dark line coding scale on the described code-wheel to be used for stopping or passing through described light, the light pulse signal that in described electric impulse signal switch process described dark line coding scale is produced is converted to low level electric impulse signal, the light pulse signal of stating clearly line coding scale generation is converted to the electric impulse signal of high level.
10. measuring method as claimed in claim 7 is characterized in that, and is further comprising the steps of before the height that carries out described electric impulse signal and/or low level pulse number count:
Described electric impulse signal is converted to square wave; With
Amplify the voltage of the described electric impulse signal of square wave.
11. measuring method as claimed in claim 7, it is characterized in that, the width starting point of described high level pulse is corresponding with the first predetermined threshold voltage on each high level pulse, and the width starting point of described low level pulse is corresponding with the second predetermined threshold voltage on each low level pulse.
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| CN 200810227084 CN101738211B (en) | 2008-11-21 | 2008-11-21 | Device and method for measuring rotation angle of engine crankshaft |
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| CN 200810227084 CN101738211B (en) | 2008-11-21 | 2008-11-21 | Device and method for measuring rotation angle of engine crankshaft |
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| CN101738211B true CN101738211B (en) | 2013-01-02 |
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Cited By (1)
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| CN103174532A (en) * | 2013-04-12 | 2013-06-26 | 南岳电控(衡阳)工业技术有限公司 | Method and device for processing crankshaft signals of electronically controlled fuel system of diesel engine |
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