CN105737750B - A kind of marine diesel horn based on photoelectric encoder and laser range sensor is away from value measurement method and device - Google Patents

Abstract

The invention discloses a method and device for measuring the arm distance value of a marine diesel engine based on a photoelectric encoder and a laser ranging sensor. The photoelectric encoder is used to collect the engine speed synchronization signal and top dead center signal in real time and output to the system control and data acquisition processing unit; the receiving unit receives the reference signal and echo signal of the transmitting unit and converts it into an electrical signal; it is processed by the peripheral data circuit Finally, the time interval is calculated by the time identification and time interval measurement unit, and the system control and data acquisition processing unit completes the conversion between the time interval and the arm distance value according to the algorithm, and realizes the corresponding relationship between the arm distance value and the crankshaft angle value. In the present invention, the transmitting unit and the receiving unit are arranged on the same side, and there is no hardware connection between the crank arms of the cylinder to be measured, and there is no possibility of the connecting rod hitting the meter when the connecting rod is installed during mechanical instrument measurement. The laser measuring arm The distance value has good reliability and high measurement accuracy, and is especially suitable for measuring the arm distance value of large-bore marine diesel engines.

Description

An Arm Distance Value of Marine Diesel Engine Based on Photoelectric Encoder and Laser Ranging Sensor Measurement method and device

technical field

The invention relates to the field of internal combustion engine measurement and control technology and fault diagnosis and maintenance.

Background technique

As the most important part of a marine diesel engine, the crankshaft accounts for about 40% of the total cost. The crankshaft structure is complex, the stress concentration is serious, and the additional stress is large. Especially when the structural strength of the crankshaft is low and the wear of the main bearing is uneven, it will cause the axis to bend, accelerate the bending fatigue damage, and in extreme cases, a broken shaft accident will occur. Therefore, regular detection of the crankshaft arm distance has become an important parameter to judge the state of the crankshaft axis, and it is also an important means to prevent the bending fatigue damage of the crankshaft.

At present, the measurement of crankshaft arm distance of marine diesel engine still adopts the traditional manual measurement method of mechanical crank table. When measuring, the crank gauge should be installed at a fixed position between the crank arms, and should be parallel to the crank pin neck. For a running diesel engine, since the piston connecting rod group has been installed on the crankshaft, when the crank is measured to be below the arm distance L at the bottom dead center position, the connecting rod is just in the middle of the crank arms on both sides, and the shift gauge cannot be installed. , in actual operation, under the arm distance value L of the crank pin at the bottom dead center, the crank pin will be located 15° before the bottom dead center and 15° behind the bottom dead center (the degree is not strictly regulated, only the symmetry and no contact with the connecting rod shall prevail) The average value of the arm distance value of the two positions 15° before L and 15° behind L is used instead, that is, under L=(15° before L+15° after L)/2. Therefore, when the connecting rod is installed, it is necessary to measure the arm distance values at five crank positions of 0°, 90°, 165°, 195°, and 270°, of which 0° is the top dead center position. The arm distance measurement of 5 crank positions can be completed at one time. Since there are measurement errors in both the reading of the crankshaft angle and the value of the shift table, and the measurement is performed with a connecting rod, it is easy for the connecting rod to collide with the shift table, causing the problem that the shift table falls off and is damaged. In order to overcome this problem, Liu Boyun, Zhu Baocheng and others from Naval Engineering University used laser and linear array displacement measurement system to try to measure the arm distance difference of diesel engine. , the above measurement method can only be applied to one deformation situation, and there are measurement limitations. Lin Jinbiao and Wang Yong from Jimei University designed a sensor that uses the Hall effect to measure the arm distance difference, and calculated the spatial distribution of the magnetic field around the cylindrical permanent magnet through the finite element analysis method, and studied the symmetrical arrangement of the two permanent magnets with the same pole. And the influence of the relative installation position of the Hall element and the permanent magnet on the measurement accuracy of the micro-displacement of the sensor, but the measurement range of this method is limited, only in the range of 0-2mm, the output of the measurement system has a linear relationship with the displacement, beyond this If the range is large, the measurement accuracy will have a large deviation.

Contents of the invention

In view of this, the content of the present invention is to provide a method and device for measuring the arm distance value of a marine diesel engine based on a crankshaft position sensor and a laser ranging sensor. It can not only avoid the problem of the connecting rod colliding with the meter that is easy to occur when the mechanical instrument is used for manual measurement, but also improve the reliability; and the measurement accuracy is high, which can minimize the measurement error. It is especially suitable for the arm distance measurement of large-bore marine diesel engines, and has great application prospects and market space.

The method for measuring the arm distance value of a marine diesel engine based on a photoelectric encoder and a laser ranging sensor provided by the present invention comprises the following steps:

1) The step of obtaining the engine speed synchronization signal and top dead center signal, install the photoelectric encoder on the free end of the crankshaft of the diesel engine, collect the engine speed synchronization signal and top dead center signal in real time, and output it to the system control and data acquisition processing unit ;

2) The step of obtaining the laser reference signal and the echo signal is to install the laser pulse emitting unit of the laser ranging sensor on the crank arm of the cylinder to be tested in the diesel engine, and arrange it on the same side as the receiving unit for real-time sending of the laser pulse signal and the reference signal. Signal; the receiving unit is used to receive laser reference signals and echo signals and convert them into electrical signals;

3) The step of calculating the time interval between the laser reference signal and the echo signal, amplifying, filtering and shaping the reference signal and the echo signal electrical signal through the peripheral data circuit, and outputting it to the time identification and time interval measurement unit, the time identification and time interval The measurement unit takes the reference signal as the timing start time and the laser echo signal as the timing end time, and calculates the time interval between the two signals accordingly;

4) The step of obtaining the arm distance value. After the counter in the system control and data acquisition processing unit collects the top dead center signal collected by the photoelectric encoder in step 1), the top dead center signal is used as the system control and data acquisition processing The counting trigger signal of the unit counter counts the square wave of the speed synchronization signal. Every time a square wave of the speed synchronization signal is collected, the counter generates an overflow interrupt and starts to execute the interrupt task. The time interval value obtained in step 3) is sent to the system control and The data acquisition and processing unit is converted into the arm distance value according to the relationship formula between the time interval and the arm distance value.

The ship diesel engine arm distance measuring device based on the photoelectric encoder and the laser ranging sensor provided by the present invention comprises:

The laser distance measuring sensor includes a laser pulse transmitting unit and a receiving unit, and the laser pulse signal transmitting unit is installed at the standard position of the crank to be measured. Its function is to transmit an optical signal of a specific wavelength, and a part of it passes through the beam splitter as a reference pulse signal. The PIN tube is converted into an electrical signal, sent to the peripheral data circuit for filtering, amplification and shaping, as the starting point of timing, the timer of the time identification and time interval measurement unit is started to start timing; the other part is reflected by the refracting prism, and shoots to the target; receiving The unit is installed on the crank and on the same side as the transmitting unit. Its function is to receive the echo signal from the laser pulse and convert the received optical signal into a DC signal of a certain voltage value. After conditioning by the peripheral data circuit, it will be used as the time Discrimination and time interval measurement unit timer timing end point;

The peripheral data circuit is connected with the echo signal and the reference pulse signal, and is used to amplify, filter and shape the input signal in real time, output to the time identification and time interval measurement unit, and calculate the time interval between the reference pulse and the echo pulse, Send it to the system control and data acquisition and processing unit, and convert the time interval into the arm distance value.

The photoelectric encoder is installed at the free end of the crankshaft of the engine, and is used to collect the engine speed synchronization signal and top dead center signal in real time and output them to the system control and data acquisition and processing unit;

Wherein, the photoelectric encoder outputs three channel signals of A, B, and C simultaneously during the rotation process, and the C channel signal is a top dead center signal. When installing the photoelectric encoder, the C channel signal should be in line with the The top dead center position of the crankshaft of the cylinder is consistent. The A-channel or B-channel signal can be used as a speed synchronization signal of the diesel engine.

The system control and data acquisition processing unit is composed of a single-chip microcomputer as the core, and is connected with the photoelectric encoder and the time identification and time interval measurement unit. After the counter in the system control and data acquisition processing unit collects the top dead center signal, it uses The top dead center signal of the photoelectric encoder is used as the counting trigger signal of the counter to count the square wave of the speed synchronization signal. By presetting the initial value of the counter, it can be realized that every time a square wave of the speed synchronization signal is collected, the counter will generate an overflow interrupt , and execute the interrupt task: use the reference pulse as the timing start trigger signal of the timer in the time identification and time interval measurement unit, use the laser echo signal as the timer timing end signal, calculate the time interval between the reference pulse and the echo pulse, and Send this value to the system control and data acquisition and processing unit, and convert it into the arm distance value according to the formula algorithm. At the same time, after the photoelectric encoder outputs the C signal, the number of A or B signals output per revolution is counted, and the crankshaft angle position corresponding to the measured arm distance value is converted, and the crankshaft angle and arm distance value are calculated in the form of a two-dimensional array. save.

It can be seen from the measurement scheme provided by the present invention above that, compared with the existing measurement methods, the method for measuring the arm distance of the marine diesel engine based on the laser ranging sensor and the photoelectric encoder of the present invention can not only avoid the safety hazards during manual measurement, Avoiding the phenomenon of the connecting rod hitting the meter during the measurement process; and can also improve the measurement accuracy and reduce the measurement error. It is especially suitable for measuring the arm distance value of large-bore marine diesel engines, and has great application prospects and market space.

Description of drawings

Figure 1 is an overall flow chart of measuring the arm distance value of a marine diesel engine based on a photoelectric encoder and a laser ranging sensor;

Fig. 2 is the principle structural diagram of photoelectric encoder;

Fig. 3 is the waveform diagram of the channel A and channel B signals output by the photoelectric encoder;

Fig. 4 is the schematic diagram of laser pulse ranging;

Fig. 5 is the composition of embodiment arm distance measuring device;

Figure 6 shows the installation position of the laser pulse ranging sensor and the position of the sampling data points.

FIG. 7 is a schematic side view of FIG. 6 .

Detailed ways

In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be described below in conjunction with the accompanying drawings and embodiments.

1. The marine diesel engine model SMIT Bolnes SB-L300 is a two-stroke DC scavenging supercharged marine diesel engine, and the theoretical value of the crankshaft arm distance is 167mm.

2. In the present invention, it should be noted that during the cranking process, the included angle between the engine crankshaft and the top dead center is called the crankshaft angle. For the engine, when the piston moves back and forth in a straight line in the cylinder, when the piston moves upward to the highest position, that is, the extreme position where the top of the piston is farthest from the crankshaft rotation center is called the top dead center.

In the present invention, it should be noted that the photoelectric encoder is a sensor that converts the mechanical geometric displacement on the output shaft into pulses or digital quantities through photoelectric conversion, and is currently the most widely used sensor. The photoelectric encoder is mainly composed of a grating disk and a photoelectric detection device. In the servo system, since the grating disc is coaxial with the motor, when the motor rotates, the grating disc and the motor rotate at the same speed. Several pulse signals are detected and output by the photoelectric detection device composed of electronic components such as light-emitting diodes. The principle structure is shown in Figure 2. Therefore, in the present invention, the angle between the crankshaft of the cylinder to be tested and the top dead center can be judged by calculating the number of output pulses of the photoelectric encoder per second.

The photoelectric encoder includes three channels A, B, and C. The rotating shaft in FIG. 2 rotates one circle. Referring to FIG. A fixed number of pulse signals will be output correspondingly. If 360 are output, it means that a square wave pulse will be output for every degree of rotation of the rotating shaft. In addition, channel C, which is not shown in Figure 3, will only output a square wave pulse when the rotating shaft rotates one revolution, and in view of the fact that the engine has only one top dead center for one revolution, the two correspond to each other, so in the present invention, define this C The channel signal is the top dead center signal, and the A channel or B channel signal is called the engine speed synchronization signal.

It should be noted that the photoelectric encoder is installed on the engine crankshaft, and every time the engine crankshaft rotates one degree, the corresponding photoelectric encoder also rotates one degree, and outputs two 0-5V pulse square wave signals, which are speed synchronization signals.

The photoelectric encoder will simultaneously output three channel signals of A, B, and C during the rotation process, and each photoelectric encoder has external output leads of the above three channels, which can facilitate external signal acquisition. In the present invention, the speed synchronization signal and the top dead center signal collected by the photoelectric encoder are connected to the interface of the single-chip microcomputer (that is, the system control and data acquisition processing unit), so as to facilitate the single-chip microcomputer to generate control signals and carry out signal acquisition processing .

It should be noted that in addition to being used for engines, photoelectric encoders can also be used in other occasions, such as motor speed measurement, etc., and can be used in engines because of the fixed correspondence between the signal characteristics of the A and C channels and the working process of the engine. Relationship, in one working cycle of the engine, the crankshaft will rotate one revolution, and the corresponding encoder will also rotate one revolution. There is only one top dead center in one working cycle of the engine. When the photoelectric encoder is installed on the crankshaft of the engine, the C channel signal of the photoelectric encoder can be artificially aligned with the top dead center, so that the engine and the encoder can be synchronized and in phase The rotation of the engine crankshaft is equivalent to outputting the rotation of the engine crankshaft to the outside in real time, which is convenient for grasping the rotation phase of the engine.

In the present invention, in terms of specific implementation, the system control and data acquisition processing unit is a single-chip microcomputer AT89C52. The counter in the single-chip microcomputer starts counting according to the speed synchronous signal square wave after collecting the top dead center signal (that is, the counting trigger signal of the counter is the top dead center signal of the photoelectric encoder), and when the counter overflows, according to the counter overflow The number of square waves of the rotational speed synchronization signal output by the time photoelectric encoder is calculated to obtain the crank angle of the engine cylinder starting from the top dead center (that is, the angle between the crank and the top dead center).

Figure 4 is a schematic diagram of the working principle of the laser pulse ranging sensor. Referring to Fig. 4 and accompanying drawing 1 at the same time, it can be seen that the trigger laser is installed at the position of the crank to be measured, and sends out laser pulses, a part of the energy passes through the beam splitter, and is directly sent to the pulse acquisition system of the peripheral data circuit as a reference pulse, as a timing starting point, The timer in the start-up moment discrimination and time interval measurement unit starts counting; the other part is reflected by the refracting prism and shoots to the target. The beam is reflected by the target surface, and the echo signal is generated and returned to the receiving unit. The receiving unit is connected with the peripheral data circuit. After amplification, filtering and shaping, the echo signal is converted into an electrical signal, and sent to the time identification and time interval measurement unit to end the timing. , the obtained time interval signal is output to the system control and data acquisition and processing unit, and the relationship formula between the time interval △t and the arm distance value △L is:

△L=c*△t/2, where c is the speed of light

The system control and data acquisition processing unit saves the arm distance value and the corresponding crankshaft angle in a two-dimensional array for subsequent calculation and analysis of the arm distance difference.

Fig. 5 is an assembly of an arm distance measuring device based on a crankshaft position sensor and a distance measuring sensor provided by the present invention.

Choose CP35MHT80 as the laser ranging sensor and fix it on the crank arm to be tested.

Time identification and time interval measurement unit selection integrated chip TDC-GP2,

In order to meet the measurement accuracy of the arm distance value, the specification of the photoelectric encoder requires outputting 24 or more speed synchronization signals per revolution. The example selects the Omron photoelectric encoder model: E6C2-CWZ6C), installs it on the free end of the crankshaft of the diesel engine, and outputs 360 square waves of speed synchronization signals per revolution.

According to the top dead center signal and speed synchronization signal of the diesel engine output by the photoelectric encoder installed at the free end of the crankshaft, the laser ranging sensor is installed on the crank arm to be tested, corresponding to each rising edge of the speed synchronization signal output by the photoelectric encoder, and the transmission The unit sends out a laser signal with a specific wavelength, and a part of it is converted into an electrical signal by a PIN tube as a reference signal, sent to the peripheral data circuit for signal amplification, filtering, and shaping, and sent to the time identification and time interval measurement unit as its internal timer. Timing trigger signal, the other part of the laser beam of the transmitting unit shoots to the opposite crank arm through the prism and generates an echo signal, the receiving unit receives the echo signal, converts it into an electrical signal through the APD tube, and sends it to the peripheral data circuit for processing as The timing end signal of the internal timer of the time identification and time interval measurement unit is used to calculate the time interval, and the analog-to-digital conversion is sent to the system control and data acquisition processing unit, which is converted into the arm distance value and converted according to the square wave number of the speed synchronization signal is the crankshaft angle position, and finally save the arm distance value and the angle position as a two-dimensional array.

System control and data acquisition and processing unit, see Figure 5, the core is the AT89C52 single-chip microcomputer, collect the top dead center signal (Z signal) of the photoelectric encoder through the P2.3 port of the AT89C52 single-chip microcomputer, use the rising edge of this signal to generate an overflow interrupt, enter Interrupt program: Use P2.4 port to collect the speed synchronization signal (A signal) of the photoelectric encoder. Every time a speed synchronization signal is collected, the built-in timer 1 of the microcontroller will generate a count overflow interrupt to trigger the laser pulse emitting unit to emit a light Signal. At the same time, the single-chip microcomputer collects a time interval value.

Figures 6 and 7 show the placement of the laser pulse trigger and the location of the sampled data points. In general, the sensor is installed on the crank, at (S+D)/2 from the center line of the crank pin, where S is the stroke of the diesel engine, and D is the cylinder diameter.

Implementation process: See attached drawing 1. After fixing the laser pulse transmitting unit and receiving unit on the same side of the crank to be tested, turn on the cranking device, and the diesel engine rotates slowly at a lower speed. When the top dead center position is reached, the photoelectric encoder Send the C signal, which is the top dead center signal, and trigger the counter in the system control and data acquisition and processing unit, that is, the 89C52 single-chip microcomputer. The counter starts to count the A signal of the photoelectric encoder, that is, the speed synchronization signal. An interrupt is generated, and the driving signal starts to be output so that the laser pulse emitting unit generates an optical signal. This optical signal is converted into an electrical signal by a PIN tube as a reference signal and then directly enters the peripheral data circuit for filtering, amplification, shaping, and identification of driving time and time. The timer in the interval measurement unit starts timing, and the optical signal of the transmitting unit reaches the target on the other side to generate an echo signal. After the signal is converted into an electrical signal by the APD tube, it is filtered, amplified, shaped, and driven by the peripheral data circuit. The timer in the identification and time interval measurement unit finishes timing, and calculates the time interval, and sends it to the system control and data acquisition processing unit. According to △L=c*△t/2, where c is the speed of light, the arm distance value is obtained, At the same time, combined with the square wave technology of the speed synchronization signal, the crankshaft angle corresponding to each arm distance value can be obtained. The system control and data acquisition and processing unit will save it in the form of a two-dimensional array, and output it to the upper computer for storage if necessary.

Through the data arrangement of the 360 points that have been measured, under the condition that the diesel engine is not equipped with connecting rods, the measurement position of the arm distance value of the diesel engine is usually taken from four points, that is, the position of the top dead center, the 90° crankshaft angle, Bottom dead center position, 270° crankshaft angle. The arm distance values corresponding to the four points are 167.515mm, 166.325mm, 166.177mm, and 167.431mm respectively.

From this, it can be obtained that the arm distance difference at the upper and lower dead centers is 167.215-166.177=1.038mm, indicating that the axis has collapsed deformation but within the specified range, which is normal.

Under the condition that the connecting rod has been installed, the measurement position of the arm distance value of the diesel engine is usually taken from five points, that is, the top dead center position, the 90° crankshaft angle, the 15° position before the bottom dead center, and the 15° position after the bottom dead center , At 270° crank angle, the corresponding arm distance values are 168.125mm, 166.452mm, 166.124mm, 165.452mm, 167.637mm respectively.

Due to the interference of the connecting rod, the arm distance value at the bottom dead center is the average value of 15° before and after it.

(166.124+165.452)/2＝165.788mm

From this, it can be obtained that the arm distance difference at the upper and lower dead centers is 168.125-165.788=2.337mm, indicating that the axis has collapsed deformation, and due to the weight of the connecting rod group, the collapsed deformation has become larger, but it is still within the specified range, which belongs to normal.

The developed arm distance value measurement device can carry out multi-turn turning, and carry out arm distance measurement and collection. Compared with the mechanical instrument measurement, it can only measure one turn of the turn, and the collected data has random errors and poor representativeness. This invention can Multi-turn cranking measurement is beneficial for multi-turn acquisition of average values, eliminating measurement errors and improving measurement accuracy.

Claims (8)

1. Away from value measurement method, 1. feature exists a kind of marine diesel horn based on photoelectric encoder and laser range sensor In comprising the following steps：

   1) photoelectric encoder is mounted on the song of diesel engine by the step of obtaining the rotation speed synchronizing signal of engine and top dead centre signal Axis free end is exported after gathering the rotation speed synchronizing signal of engine and top dead centre signal in real time at system Control ＆ data acquisition Manage unit；

   2) the step of obtaining reference laser light signal and echo-signal, the laser pulse emission unit of laser range sensor is installed It on the crank arm of diesel engine cylinder to be measured, is arranged with receiving unit homonymy, for sending measurement pulse signal and reference in real time Signal；Receiving unit is used to receive reference laser light signal and echo-signal and is converted to electric signal；

   3) the step of calculating reference laser light signal and echo-signal time interval to reference signal and is returned by peripheral data circuit Ripple signal electric signal is amplified, filters and shaping, is output to and differentiates constantly and time-interval-unit, the moment differentiate and when Between interval measurement unit using reference signal as timing start time, using laser echo signal as timing finish time, and according to This calculates the time interval of two signals；

   4) the step of arm is away from value is obtained, the light in step 1) is collected of the counter in system Control ＆ data acquisition processing unit After the top dead centre signal of photoelectric coder acquisition, using the top dead centre signal as system Control ＆ data acquisition processing unit counter Counting trigger signal, rotation speed synchronizing signal square wave is counted, often gathers a rotation speed synchronizing signal square wave, counter is It generates to overflow and interrupt, start to perform interrupt task, by gained time interval numerical value is sent into system control in step 3) and data are adopted Collect processing unit, according to time interval and relation formula of the arm away from value, be converted into arm away from value.
2. 2. arm as described in claim 1 is away from value measurement method, it is characterised in that：Basis is installed to crankshaft free-end in step 4) Photoelectric encoder output diesel engine top dead centre signal and rotation speed synchronizing signal, be installed to and treated using laser range sensor It surveys on crank arm, each rotation speed synchronizing signal rising edge of corresponding photoelectric encoder output, transmitter unit is sent with specific The laser signal of wavelength, a part are sent to peripheral data circuit and carry out signal as electric signal is converted to through PIN pipes with reference to signal Amplification, filtering, shaping are sent into moment discriminating and time-interval-unit, start the triggering of timing as its internal timer Signal, another part laser beam of transmitter unit through prism directive offside crank arm and generate echo-signal, and receiving unit receives Echo-signal after APD pipes are converted to electric signal, is sent into peripheral data processing of circuit, is surveyed as differentiating constantly with time interval The timing end signal of unit internal timer is measured, calculates time interval, system control is sent into after analog-to-digital conversion and data are adopted Collect processing unit, according to time interval and relation formula of the arm away from value, be converted into arm away from value.
3. 3. arm as claimed in claim 1 or 2 is away from value measurement method, it is characterised in that：Time interval △ t are with arm away from value △ L's Relation formula is：

   △ L=c* △ t/2, wherein c are the light velocity.
4. 4. arm as described in claim 1 is away from value measurement method, it is characterised in that：The photoelectric encoder is same in rotation process When externally exported tri- channel signals of A, B, C, the C-channel signal is top dead centre signal, i.e., at the time of C-channel signal occurs At the time of should being that tested cylinder crank is in top dead center position, the A channel signal or channel B signal be same for the rotating speed of engine Walk signal.
5. 5. arm as described in claim 1 is away from value measurement method, it is characterised in that：System Control ＆ data acquisition processing unit with Microcontroller forms for core, and the output signal of photoelectric encoder is counted using microcontroller internal counter, a counting Device gathers C-channel signal, counts and interruption is generated when overflowing, and starts another counter and A channel signal square wave is counted, A Each square wave of channel signal can be generated once to count to overflow and interrupted, and effect is to make system control and data acquisition process unit A square-wave signal, control signal of this signal as laser pulse emission unit are exported, while also serves as system control sum number According to acquisition process unit to differentiating the sampling control signal with time-interval-unit output signal constantly.
6. 6. arm as described in claim 1 is away from value measurement method, it is characterised in that：Laser pulse emission unit and receiving unit Normal mounting position is crank arm homonymy, and at crank pin center (S+D)/2, wherein S is the stroke of diesel engine, and D is cylinder diameter.
7. Away from value measurement mechanism, 7. feature exists a kind of marine diesel horn based on photoelectric encoder and laser range sensor In, including：

   Photoelectric encoder, mounted on the crankshaft free-end of diesel engine, for gather in real time the rotation speed synchronizing signal of engine and Endstop signal simultaneously exports and gives system Control ＆ data acquisition unit；

   Laser range sensor, including laser pulse emission unit and receiving unit, laser pulse emission unit is mounted on to be measured Measure the normal place of crank, receiving unit is mounted on crank, and with transmitter unit homonymy, laser pulse emission unit is for real When send measurement pulse signal and reference signal；Receiving unit is used to receive reference laser light signal and echo-signal and is converted to electricity Signal；

   Peripheral data circuit, is connected with echo-signal and reference burst signal, for reference signal and echo-signal telecommunications It number is amplified, filters and shaping, be output to and differentiate constantly and time-interval-unit；

   System Control ＆ data acquisition processing unit differentiates with photoelectric encoder and moment and is connected with time-interval-unit It connects, for receiving top dead centre signal, rotation speed synchronizing signal and the time interval time signal of photoelectric encoder output.
8. 8. arm as claimed in claim 7 is away from value measurement mechanism, it is characterised in that：The system Control ＆ data acquisition processing is single First core is AT89C52 microcontrollers, passes through the top dead centre signal of the P2.3 mouth acquisition photoelectric encoders of AT89C52 microcontrollers；Profit With the rotation speed synchronizing signal of P2.4 mouthfuls of acquisition photoelectric encoders.