CN101738211B - Device and method for measuring rotation angle of engine crankshaft - Google Patents

Abstract

The invention discloses a measuring device for the rotation angle of the engine crankshaft, which comprises: an encoding disk, which rotates together with the engine crankshaft and generates an optical pulse signal; signal, and convert the optical pulse signal into an electric pulse signal; the signal collector is used to collect the high and/or low level pulse quantity of the electric pulse signal; and the signal processor, according to the high and/or The number of low level pulses obtains the angle of rotation of the engine crankshaft. The invention can provide high-precision measurement of the crank angle of the engine. The invention also discloses a method for measuring the crank angle of the engine.

Description

Measuring device and method for engine crankshaft angle

technical field

The invention relates to measurement technology, in particular to a measurement device and method for engine crank angle.

Background technique

With the development of automobile technology and the improvement of national emission standards, the requirements for engine control are getting higher and higher. To achieve precise control of the engine, it is first necessary to achieve accurate measurement and collection of various engine data. Among the many data of the engine, its crankshaft angle is an important data.

The crankshaft angle of the engine is determined by the angles corresponding to the different positions passed by the crankshaft during one revolution, and the corresponding piston position is obtained through the crankshaft angle, thereby determining the ignition time of the engine. Whether the ignition time of the engine is correct is directly related to the power output of the engine and the combustion of fuel (whether the emission is up to standard). The main hazards brought when the ignition time of the engine is incorrect are: 1. Too early ignition time of the engine will cause knocking, thereby damaging the engine or reducing its life. 2. If the ignition time of the engine is too late, the fuel will be discharged due to insufficient combustion, causing air pollution, so that the emission is seriously not up to standard. 3. Whether the ignition time of the engine is advanced or too late, the power output of the engine will be insufficient.

At present, the commonly used crank angle detection device is an electromagnetic sensor, that is, a gear plate with a certain number of teeth is installed on one end of the crankshaft of the engine, and then an electromagnetic induction element (such as a Hall element) is fixedly installed at a certain position relative to the gear plate. In this way, when the engine rotates, the teeth installed on the chainring at one end of the crankshaft will approach the electromagnetic induction element successively, thereby generating a waveform similar to a sine wave corresponding to the number of teeth at the signal output end of the electromagnetic induction element. The output waveform of the electromagnetic sensor is a differential signal, which is transformed into a square wave with the same frequency through conversion processing, so the specific position of the crankshaft one revolution is determined according to these square waves.

However, the existing electromagnetic sensors have the following disadvantages: (1) the number of teeth of the tooth plate is small, and the accuracy of the sensor is low; The peak value of the voltage signal varies greatly, and the approximate waveform comparison is shown in Figure 3. As shown in the figure, the voltage at low speed is very small (generally only a few volts), and at high speed the voltage is very large (can reach tens of volts), so the voltage impact on the chip processing the signal is very large, causing damage to the chip (3) In the process of square wave conversion, the pulse width of the square wave will be different due to the difference in the amplitude of the sensor with the speed of the speed, resulting in errors, resulting in a large test error generated by this type of sensor ; (4) The installation requirements of this type of sensor are relatively high, mainly referring to that the relative position of the gear plate and the electromagnetic induction element must be the same, otherwise the error of the generated waveform will be greater.

Therefore, the engine crank angle measurement device in the prior art cannot provide accurate rotation angle measurement.

Contents of the invention

The object of the present invention is to solve at least one of the above-mentioned problems in the prior art.

Therefore, the present invention proposes a method and device for measuring the crank angle of an engine, thereby providing accurate measurement of the crank angle.

According to one aspect of the present invention, the device for measuring the crank angle of the engine crankshaft provided by the embodiment of the present invention includes: an encoder disc, which rotates together with the engine crankshaft and generates an optical pulse signal; a photoelectric sensor, which is used to sense the rotation process of the encoder disc and the engine crankshaft The optical pulse signal generated in the optical pulse signal, and convert the optical pulse signal into an electrical pulse signal; the signal collector is used to collect the high and/or low level pulse quantity of the electrical pulse signal; and the signal processor, according to the The number of high and/or low level pulses to obtain the angle of rotation of the engine crankshaft.

According to another aspect of the present invention, an embodiment of the present invention proposes a method for measuring the crankshaft angle of an engine, comprising the following steps: setting an encoder disc that rotates together with the crankshaft of the engine; during the process that the encoder disc rotates with the crankshaft of the engine, Emitting light to the code disc to generate an optical pulse signal; collecting the optical pulse signal and converting it into an electrical pulse signal; counting the number of high and/or low level pulses of the electrical pulse signal; and according to the high and/or low-level pulse counts to obtain the rotation angle of the engine crankshaft.

The invention applies the photoelectric sensor and the photoelectric encoder disk to the measurement of the rotation angle of the engine crankshaft, which can greatly improve the measurement accuracy of the rotation angle, thereby providing a basis for accurately controlling the ignition time of the engine, and improving the overall performance of the engine as a whole, reducing the emissions of pollutants. Moreover, not only the electrical pulse signal waveform output by the photoelectric sensor is not affected by the engine speed, but also the voltage amplitude of the waveform remains unchanged at high and low engine speeds. In this way, the voltage impact on the chip processing the photoelectric sensor signal can be avoided, and the reliability of the entire measuring device can be improved.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, wherein:

Fig. 1 is the structural block diagram of the engine crank angle measuring device of the embodiment of the present invention;

Fig. 2 is a top view and a front view of the installation structure of the code disc and the photoelectric sensor of the embodiment of the present invention;

Fig. 3 is the example of the electrical pulse signal waveform figure that photoelectric sensor of the present invention outputs;

Fig. 4 is the electric pulse signal that the photoelectric sensor of the present invention outputs after waveform conversion and amplified waveform diagram example;

Fig. 5 is a flow chart of the steps of the method for measuring engine crankshaft angle of the present invention; and

Fig. 6 is a flow chart of the steps of obtaining the crank angle by combining the pulse width timing according to the embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

First, please refer to FIG. 1 , which is a structural block diagram of an engine crank angle measuring device according to an embodiment of the present invention.

As shown in the figure, the measuring device of the present invention includes a code disc 12 , a photoelectric sensor 14 , a signal collector 16 and a signal processor 18 . The encoder disc 12 rotates together with the crankshaft of the engine, and generates light pulse signals by receiving the light emitted by the light emitter (not shown in the figure) of the photoelectric sensor 14 . The photoelectric sensor 14 also includes a light receiver (not shown in the figure) for receiving the light pulse signal generated by the encoder disc 12 . The photoelectric sensor 14 senses the light pulse signal generated during the rotation of the encoder disk 12 and the crankshaft of the engine according to the received light signal of the light receiver, and converts the light pulse signal into an electric pulse signal.

The signal collector 16 is connected to the output end of the photoelectric sensor 14, so as to collect the electric pulse signal converted by the photoelectric sensor 14, and count the number of high and/or low level pulses of the electric pulse signal. The signal collector 16 inputs the timing result into the signal processor 18, and the signal processor 18 obtains the rotation angle of the engine crankshaft according to the number of high and/or low level pulses.

In addition, the signal collector 16 collects the number of pulses for one rotation of the engine crankshaft, that is, the measurement accuracy is related to the resolution of the photoelectric sensor 14 . For example, when the resolution of the photoelectric sensor 14 is 20KHz, that is, the maximum number of pulses that the photoelectric sensor 14 can handle in 1 second is 20K, if the crankshaft of the engine rotates 100 circles in 1 second, then the crankshaft rotates once During the process, the photoelectric sensor 14 can handle up to 200 rotation angle pulses output by the crankshaft. That is to say, during one rotation with the crankshaft of the engine, the encoder disk 12 generates up to 200 optical signal pulses. Therefore, when the maximum engine speed is constant, the higher the resolution of the photoelectric sensor 14, the smaller the crank angle corresponding to each optical signal pulse, which can greatly improve the measurement accuracy of the crank angle. However, since the data processing capability of the signal collector 16 is limited, the measurement accuracy cannot be set too high. In practical applications, the resolution of the photoelectric sensor 14 can be set to an appropriate size based on the number of electrical pulse signals processed by the signal collector 16 .

The installation structure diagram of the code disk 12 and the photoelectric sensor 14 is shown in FIG. 2 , and FIG. 2 shows an embodiment of an installation configuration relationship of the code disk 12 and the photoelectric sensor 14 from the top view and the front view. As shown in the figure, the coding disc 12 is uniformly provided with alternate bright pattern coding scales g1 and dark pattern coding scales g2, which are respectively used to block or emit light through the light emitter . The center of the optical axis of the photoelectric sensor 14 (h represents the centerline of the optical axis in FIG. 2 ) corresponds to the central holes of the encoding scales g1 and g2, so that the encoding disc 12 can receive light more sensitively and generate accurate optical pulse signals.

It should be pointed out that the embodiment in FIG. 2 is only for the purpose of illustration, and is not intended to limit the present invention. For example, the code disk 12 is a code tooth disk, and its outer edge is uniformly provided with teeth and tooth gaps, which are respectively used to block or pass the light emitted from the light emitter of the photoelectric sensor 14 .

Now, referring back to FIG. 1 , the engine crank angle measuring device according to the embodiment of the present invention will be described in detail in combination with different structures of the code disc.

For the code disc 12 with bright pattern and dark pattern coding scales g1 and g2 shown in Fig. 2, during the rotation process of the code disc 12 and the crankshaft of the engine, the light emitter of the photoelectric sensor 14 emits to the code disc 12 bright pattern coding scale g1 The light on the top will pass through it, and the light emitted to the dark pattern coding scale g2 will be reflected and transmitted to the light receiver of the photoelectric sensor 14. Therefore, the photoelectric sensor 14 senses the corresponding optical pulse signal generated by the encoder disc, and converts the rotational angular displacement of the crankshaft into an electrical pulse signal through photoelectric conversion. Here, the photoelectric sensor 14 converts the light pulse signal generated corresponding to the dark pattern coding scale g2 into a low-level electric pulse signal, and converts the light pulse signal generated corresponding to the bright pattern coding scale g1 into a high-level electric pulse signal.

Similarly, for the encoder disc 12 with teeth and tooth gaps, the photoelectric sensor 14 converts the optical pulse signal generated by the teeth of the encoder disc 12 into a low-level electrical pulse signal, and converts the optical signal pulse generated by the tooth gap into High level electric pulse signal.

The waveform of the electrical pulse signal output by the photoelectric sensor 14 is shown in the embodiment of FIG. 3 , and the output electrical pulse is approximately a rectangular pulse. In addition, since the output waveform voltage of the photoelectric sensor signal is not affected by the crankshaft speed of the engine, the voltage amplitude of the waveform can remain unchanged at high speed and low speed.

The signal collector 16 can count the high-level and low-level pulses in sequence according to the electrical pulse signal output by the photoelectric sensor 14 in units of a single high-level/low-level pulse; or the sum of high-level and low-level pulses as a unit , count only high or low levels. Setting the signal collector 16 to count a single high-level or low-level pulse can reduce the complexity and processing time of the counting process performed by the signal collector 16 . Of course, the smaller the level pulse unit counted, the smaller the rotation angle corresponding to each count pulse, and the higher the precision of the corresponding rotation angle measurement. Therefore, the pulse counting unit of the signal collector 16 can be appropriately set according to actual needs.

The signal processor 18 counts the corresponding encoding disc rotation angle according to the level pulse quantity output by the signal collector 16 and a single pulse, for example, when only high/low level pulses are counted, if there are 120 identical If the teeth are large or small, the corresponding rotation angle between an adjacent tooth and the missing tooth is 3 degrees, and the corresponding angle corresponding to a high/low level pulse count is 3 degrees. Therefore, the signal processor 18 can obtain the angle by which the crankshaft has rotated by converting the number of pulses.

In addition, in one embodiment, the crank angle measuring device of the present invention may further include a waveform converter 20 and an amplifier 22 . As shown in the corresponding part of the dotted line in Figure 2, the waveform converter 20 converts the electrical pulse signal output by the photoelectric sensor 14 into a standard rectangular wave. For example, the waveform converter 20 is a NOT gate circuit. After processing, a rectangular wave can be obtained. Of course, the waveform converter 20 of the present invention is not limited to this specific embodiment, and any device that can be used for rectangular wave conversion in the prior art is applicable to the present invention. The amplifier 22 is used to further amplify the rectangular wave voltage output by the waveform converter 20 , for example, the obtained electric pulse signal waveform is shown in FIG. 4 . The rectangular wave output by the waveform converter 20 can facilitate the accurate counting of the electric pulse signal by the signal collector 16, and through the amplification of the voltage value of the rectangular wave by the amplifier 20, the intensity voltage value of the electric pulse signal can reach the corresponding signal acquisition. Within the identification range of the signal collector 16, for example, the high level is amplified to 5V, and the low level is amplified to 1V, so that the signal collection accuracy of the signal collector 16 can be further improved.

In one embodiment, the signal collector 16 may further include a pulse width timing unit (not shown in the figure), and the pulse width timing unit is used for timing according to the high/low level pulse width of the electric pulse signal. And, the signal processor 18 also includes a pulse width processing unit (not shown in the figure), to determine the motor corresponding to a certain width of a single high/low level pulse according to the timing of the width of the high/low level pulse by the pulse width timing unit. The angle of rotation of the crankshaft. The purpose of setting the pulse width timing unit and pulse width processing unit is to further improve the detection accuracy of the crank angle, and to meet the requirement that the crank angle corresponding to the ignition position is located in the middle of the two pulses, that is, to solve the problem when the required ignition angle just falls between the two pulses. The problem of precise ignition cannot be achieved.

In the following, the working principles of the pulse width timing unit and the pulse width processing unit will be described respectively with reference to the embodiments of FIG. 3 and FIG. 4 .

The pulse width timing unit is used to time the width of the pulse while the signal collector 16 counts the number of pulses of the electrical pulse signal, and the pulse width timing unit starts from the starting point of each high/low level pulse width of the electrical pulse signal timing. In one embodiment, for a high-level pulse, the starting point of its width corresponds to the first predetermined threshold voltage on each high-level pulse; for a low-level pulse, its width starting point corresponds to the second predetermined threshold voltage on each low-level pulse. threshold voltage corresponds to. In detail, the starting point and ending point of the width of the high-level pulse correspond to the first predetermined threshold voltage value of the rising edge and the falling edge of the pulse, respectively, and the starting point and ending point of the width of the low-level pulse correspond to the first predetermined threshold voltage value of the falling edge and the rising edge of the pulse. The two predetermined threshold voltages correspond respectively. That is to say, the pulse width timing unit can determine the starting point for starting width timing according to the voltage value points that divide the high and low levels of the electric pulse signal. Since the code disc is evenly provided with teeth and tooth gaps or bright and dark coding scales, the widths of the corresponding adjacent high-level pulses and low-level pulses generated by them are still approximately the same when the crankshaft speed changes.

The pulse width timing unit can perform timing continuously or at predetermined time intervals, and correspondingly output the timing value to the pulse width processing unit of the signal collector 16 . Of course, the shorter the timing interval, the higher the timing accuracy of the current pulse width by the pulse width timing unit. Correspondingly. The angle obtained by the pulse width processing unit processing the timing is more accurate.

For example, for the electrical pulse signal shown in Figure 3, the pulse width timing unit can start a high-level pulse width timing from the corresponding point of the first predetermined threshold voltage 2.4V on the rising edge as the width starting point, and start from the second predetermined threshold voltage on the falling edge The corresponding point of the voltage 0.4V is used as the starting point of the width to start timing the width of a low-level pulse. In this way, by timing the pulse width between the rising edge and the falling edge of the 2.4V voltage, the timing time corresponding to a certain width and the entire width of the high-level pulse can be obtained. In the same way, the timing time corresponding to a certain width and the entire width of the low-level pulse can be obtained. Certainly, the first predetermined threshold voltage and the second predetermined threshold voltage of the present invention are not limited to the specific embodiment, and the pulse width timing unit can perform corresponding high level and low level voltage points from the corresponding voltage value point of arbitrarily dividing high level and low level. The width of the flat pulse is timed. For the electrical pulse signal shown in FIG. 4 , the starting point of the width of each high and low level pulse is the corresponding point of its rising edge and falling edge respectively. Here, the pulse width timing unit only counts the width of each current high/low level pulse, and restarts timing from the starting point of the width of the next level pulse if the entire pulse width is timed.

As shown in the embodiment of Figure 3, the pulse width timing unit can obtain the timing time t1 corresponding to the entire width of a single high/low level pulse and the timing time t1 corresponding to a certain width of the adjacent current single high/low level pulse through pulse width timing. time t2. The pulse width processing unit calculates their ratio according to the ratio of the timing time t2 of the current high/low level pulse width to the timing time t1 corresponding to the entire width of the previous high/low level pulse, and then calculates their ratio according to the ratio and t1 time The crank angle corresponding to the single high/low level pulse determines the crank angle corresponding to the level pulse width at time t2. Since the speed of the crankshaft will constantly change during actual operation, in order to obtain the crank angle corresponding to the current level pulse width more accurately, in the embodiment of the present invention, the timing time of the entire width of the previous pulse adjacent to the current level pulse is Based on the corresponding calculation of the rotation angle.

。信号处理器18根据当前的3个脉冲计数、单个高/低电平脉冲对应的曲轴转角

、脉冲宽度处理单元确定的计时比值

，可以确定当前曲轴旋转过的角度为

。Below, a detailed description will be made in conjunction with specific embodiments. Assuming that 120 teeth are evenly arranged on the code disc 12, that is, the corresponding rotation angle of each tooth is 3°, and the code disc 12 provided with this structure, the output of the photoelectric sensor 14 and the electric current of the waveform converter 20 and the amplifier 22 The waveform diagram of the pulse signal is shown in Figure 4. Taking the 0 o'clock position in Fig. 4 as the reference point, in the process of the encoder disc 12 rotating with the crankshaft of the engine, the current signal collector 16 only counts the high/low level of the electric pulse signal, and the pulse count is 3, That is, there are 3 high-level pulses or low-level pulses, and each count of a high/low-level pulse indicates that the crankshaft has rotated an angle of 3°. And, the timing time of the current pulse width of the pulse width timing unit is t0, the timing time corresponding to the entire width of the previous pulse is t0. Therefore, the pulse width processing unit obtains their ratio according to these two width times as

. The signal processor 18 counts according to the current 3 pulses, and the crank angle corresponding to a single high/low level pulse

, the timing ratio determined by the pulse width processing unit

, it can be determined that the current rotation angle of the crankshaft is

.

When the measured angle is used for engine ignition, if the ignition advance angle of the set engine is 10°, then when the crankshaft rotates through the angle size, the corresponding measured angle value is sent to the engine control unit (ECU) by the signal processor 18 ECU), so that in this position the ECU can control the engine to start ignition.

Of course, the pulse counting and width timing of the present invention are not limited to this specific embodiment, for example, the counting of the signal processor can be a single high and low level pulse as a unit, and the pulse width timing unit is also clocked with the width of a single level pulse , or, counting in units of a high-level pulse and a low-level pulse, and pulse width timing in corresponding units, etc., are all applicable to the pulse counting and width timing of the present invention.

In addition, the measurement system of the present invention may further include a display unit, which is used to display the rotation angle data of the engine crankshaft output by the signal processor 18 .

Through the engine crank angle measuring device of the present invention, the current crank angle can be accurately measured, thereby providing an accurate crank angle signal for an engine control unit (ECU) for controlling the ignition time of the engine. In addition, the present invention can further improve the precision of the rotation angle measurement by counting the pulse width of a single pulse while counting the electrical signal pulses. When the rotation angle corresponding to the ignition position of the engine is between the two counted pulses, the pulse count of the measured rotation angle can be further subdivided by the pulse width timer, so as to obtain a higher precision measurement of the rotation angle, and this method is used for Accurate measurement data can be obtained even when the engine speed fluctuates widely.

Next, please refer to FIG. 5 , which is a flow chart of the steps of the method for measuring the crankshaft angle of the engine according to the present invention.

As shown, the method includes the following steps: First, an encoder disc is set to rotate with the crankshaft of the engine (step 102). In one embodiment, the encoding disc can be uniformly provided with alternate bright pattern coding scales and dark pattern coding scales in a ring shape, and the bright pattern coding scales and the dark pattern coding scales are used to block or pass light respectively. Alternatively, the code disc is a code tooth disc, and its outer edge is evenly provided with teeth and tooth gaps, which are also used to block or pass light respectively. However, it should be pointed out that the encoder disk of the present invention is not limited to these embodiments, and any photoelectric encoder disk in the prior art is applicable to the present invention.

Then, during the process of the encoder disc rotating together with the crankshaft of the engine, light is emitted to the encoder disc to generate a light pulse signal (step 104 ). For example, for the code disc with the above-mentioned coded scale with bright and dark patterns, during the rotation of the code disc and the engine crankshaft, the light emitted to the coded scale of the code disc will pass through it and be emitted to the dark pattern. The light on the coded scale is reflected. Likewise, for a disc with teeth and gaps, light is transmitted through the gaps and reflected at the teeth.

Next, collect according to the optical pulse signal generated by the encoder disc, and convert it into an electrical pulse signal (step 106). The optical pulse signal corresponding to the encoder disc is converted into an electrical pulse signal through photoelectric conversion. In one embodiment, the light pulse signal generated corresponding to the coded scale of the dark pattern of the code disk can be converted into a low-level electric pulse signal, and the light pulse signal generated corresponding to the coded scale of the bright pattern can be converted into a high-level electric pulse signal . Alternatively, for an encoder disc with teeth and tooth gaps, the optical pulse signal generated by the teeth is converted into a low-level electrical pulse signal, and the optical signal pulse generated by the tooth gap is converted into a high-level electrical pulse signal.

The electrical pulses output by the photoelectric conversion are approximately rectangular pulses, and the number of level pulses needs to be counted according to the converted electrical pulse signal (step 108 ). Here, the number of level pulses of the electrical pulse signal can be counted in units of a single high/low level pulse, respectively counting high level and low level pulses in turn; or taking the sum of high level and low level as a unit, only counting high level pulses Level or low level to count.

Next, an angle conversion is performed according to the high and/or low level pulse counts to obtain the rotation angle of the engine crankshaft (step 110). According to the counting of the number of level pulses and the encoder disc rotation angle corresponding to a single pulse count, for example, when only high/low level pulses are counted, if 120 teeth of the same size are uniformly arranged on the encoder disc, the adjacent The rotation angle corresponding to a tooth and tooth gap is 3 degrees, and the corresponding angle corresponding to a high/low level pulse count is 3 degrees. Therefore, by converting the number of pulses, the angle by which the crankshaft has rotated can be obtained.

In addition, in one embodiment, the following steps may be included before counting the number of electrical pulse signal levels in step 108: converting the electrical pulse signal output in step 106 into a standard rectangular wave, and amplifying the rectangular wave . For example, the electrical pulse signal can be converted into a standard rectangular wave by simply processing the electrical pulse signal with a NOT gate. Converting to a rectangular wave can facilitate accurate counting of electrical pulse signals of the waveform in step 108 . Certainly, the waveform conversion step of the present invention is not limited to this specific embodiment, and any method in the prior art that can be used for rectangular wave conversion is applicable to the present invention.

The purpose of amplifying the rectangular wave is to make the voltage values corresponding to its high and low levels within the recognizable range of level pulse acquisition, so as to further improve the accuracy of counting the number of pulses.

In addition, the method for measuring the crank angle of the engine according to the present invention may further include the step of timing each pulse width. The purpose of pulse width timing is to further improve the detection accuracy of the crank angle, and to meet the requirement that the crank angle corresponding to the ignition position is located in the middle of the two pulses, that is, to solve the problem that the required ignition angle just falls between the two pulses and cannot achieve accurate Ignition problem.

Please refer to FIG. 6 for a specific embodiment of this step. FIG. 6 is a flow chart of steps for obtaining the crankshaft angle in combination with pulse width timing according to an embodiment of the present invention.

While counting the number of high/low level pulses of the electric pulse signal, counting is started from the width starting point of each high/low level pulse of the electric pulse signal (step 202). However, the present invention is not limited to this specific embodiment. For example, pulse width timing can also be performed in units of adjacent high-level pulses and low-level pulses. Of course, in this case, the accuracy of timing will be reduced. .

In one embodiment, for a high-level pulse, the starting point of its width may correspond to the first predetermined threshold voltage on each high-level pulse; for a low-level pulse, its width starting point may correspond to the first predetermined threshold voltage on each low-level pulse. The two predetermined threshold voltages correspond. The starting point and end point of the width of the high-level pulse correspond to the first predetermined threshold voltage value of the rising edge and the falling edge of the pulse respectively, and the starting point and end point of the width of the low-level pulse correspond to the second predetermined threshold voltage value of the falling edge and the rising edge of the pulse. correspond respectively. That is, the starting point for starting single pulse width timing can be determined according to the voltage value points that divide the high and low levels of the electric pulse signal. Since the code disc is uniformly provided with the same size teeth and tooth gaps or bright and dark coding scales, when the crankshaft speed changes, the widths of the corresponding adjacent high-level pulses and low-level pulses generated by them are approximately equal.

Here, for example, in combination with the embodiment of FIG. 3 , an exemplary description can be made on the setting of the first predetermined threshold voltage and the second predetermined threshold voltage of the electric pulse signal. As shown in FIG. 3 , the 2.4V of the rising edge can be set as the first The predetermined threshold voltage corresponds to the width starting point of a high-level pulse width timing, and 0.4V of the falling edge is set as the second predetermined threshold voltage, corresponding to the width starting point of a low-level pulse width timing. In this way, by timing the pulse width between the rising edge and the falling edge of the 2.4V voltage, the timing time corresponding to a certain width and the entire width of the high-level pulse can be obtained. In the same way, the timing time corresponding to a certain width and the entire width of the low-level pulse can be obtained. However, it should be pointed out that the setting of the threshold voltage corresponding to the starting point of the width of the high and low level pulses of the present invention is not limited to this specific embodiment. For example, as shown in FIG. 3 , according to the voltage value divided by the high and low levels of the electric pulse signal, the first predetermined threshold voltage and the second predetermined threshold voltage can be set at any suitable voltage position between 0.4V and 2.4V.

Therefore, the first predetermined threshold voltage and the second predetermined threshold voltage of the present invention can carry out timing corresponding to the width of the high and low level pulses from the voltage point of arbitrarily dividing the high and low levels. Of course, when the crankshaft rotates at a constant speed, the corresponding The divided high and low pulse widths are the same. For the electrical pulse signal that has undergone rectangular wave conversion and voltage amplification, the starting point of the width of each high-level and low-level pulse is the corresponding point of its rising edge and falling edge, respectively.

In addition, the pulse width timing can only be timed for the width of each current high/low level pulse. If the entire pulse width is timed, the timing will be restarted from the starting point of the width of the next level pulse.

Therefore, through pulse width timing, the time t2 corresponding to a certain width of the current single high/low level pulse can be obtained (step 204 ). The counting time t2 can be counted and output continuously or at predetermined time intervals according to the change of the pulse width of the current level. The smaller the timing interval, the higher the timing accuracy of the current pulse width. Next, according to the timing time t2 of the current high/low level pulse width and the timing time t1 corresponding to the entire width of the previous high/low level pulse, their ratio t2/t1 is calculated (step 206). Timing time t1 is the timing between the start point and the end point of the previous high/low level pulse width. Therefore, according to the ratio and the crank angle corresponding to the single high/low level pulse at time t1, the crank angle corresponding to the current level pulse width at time t2 can be determined (step 208).

In the embodiment of the present invention, the calculation of the corresponding rotation angle is performed on the basis of the timing time of the entire width of the previous pulse adjacent to the current level pulse, because the speed of the crankshaft will continue to change during actual operation, but two adjacent level pulses The corresponding speed change is small, and the corresponding widths of two adjacent level pulses are approximately the same. Therefore, in order to obtain the crank angle corresponding to the pulse width of the current level more accurately, the embodiment of the present invention uses the timing time of the entire width of the previous pulse to calculate the rotation angle of the pulse width of the current level.

Finally, add the crank angle corresponding to the high/low level pulse count and the crank angle corresponding to the current width to obtain the current rotated angle of the crank shaft (step 210 ). Therefore, when the rotation angle corresponding to the ignition position of the engine is between the two counted pulses, the pulse count of the measured rotation angle can be further subdivided by the pulse width timer, so as to obtain a more accurate measurement of the rotation angle, and this The method can also obtain accurate measurement data when the engine speed fluctuates greatly. Through the method for measuring the engine crank angle of the present invention, the angle that the current crankshaft has rotated can be accurately measured, thereby providing an accurate crank angle signal for an engine control unit (ECU) for controlling the ignition time of the engine.

In addition, the measurement method of the present invention may also include a step of displaying the rotation angle data of the engine crankshaft, so as to provide relevant personnel with real-time and direct measurement data.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

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.

Images