SU900188A1 - Device for checking rotation speed - Google Patents

Description

I

The invention relates to a technique of measurement and control and can be used to measure the frequency of rotation of the shafts of internal combustion engines.

Known contactless electronic devices containing an angular velocity sensor and a measuring circuit with a reading device at the output. An inductive angular velocity sensor is installed against the orifice (lip) on the engine flywheel. At the time of the passage of the hole of the flywheel against the sensor, the latter generates a pulse. The frequency of the pulses, proportional to the frequency of rotation of the motor shaft, is converted by the measuring circuit into a voltage, which is then measured by the reading device C 11.

However, these devices are used only in engines that have access to rotating parts.

and the ability to install an angular velocity sensor.

The closest to the technical essence of the invention is a device comprising a vibration sensor connected in series, an amplifier, a frequency selection, a threshold device, a pulse shaper, a source of reference voltage connected between the output of the frequency selector and another input of the threshold device measuring unit. In this case, the vibration sensor is installed on the engine block

15 or any other outdoor part. During operation, the moving parts of the engine periodically hit each other, for example, the piston strikes the liner when it is repacked, the valve distribution mechanism strikes the housing, the injector moving parts hit its housing, and the pipeline to the injector is deformed at the moment of fuel injection .

The vibration sensor captures all these shock processes in the form of a sequence of vibroacoustic signals of different amplitudes, durations and frequencies. The frequency selector selects a signal with the most intense frequency components of the signal spectrum. The threshold device transmits to its output only those signals that exceed the level of the reference voltage in amplitude. The latter is produced by the source of the reference voltage and is proportional to the average or amplitude value of the entire sequence of signals.

At the output of the pulse former, a sequence of pulses is formed, the frequency of which is proportional to the frequency of rotation of the engine crankshaft. The measuring unit converts this pulse sequence into a convenient I2l signal,

A disadvantage of the known device is the relatively low accuracy of control of the rotational frequency, since the amplitudes of the vibroacoustic coils due to the random intensity of the shock processes have a considerable variation even at a constant frequency of rotation of the motor shaft. If any particular signal exceeds the reference level in amplitude within one revolution, it passes to the output of the threshold device and then to the measuring unit. If the same signal during the next revolution due to a decrease in amplitude does not exceed the reference level, it will pass to the output of the threshold device and then to the measuring unit. As a result, even at a constant rotational frequency, the number of pulses goes through the measuring unit, which reduces rotational speed control accuracy.

The purpose of the invention is to improve the accuracy of control,

The goal is achieved by the fact that a device containing a series-connected vibration sensor, an amplifier, often a selector, a threshold device, a pulse shaper, and a HV source connected between the output of the frequency selector and another input of the threshold device, additionally introduced a time ratio block and the tolerance control unit, while the input of the relationship block and the first input of the tolerance control unit are connected to the output of the pulse shaper, the second input of the unit is tolerated go control is connected to the output of the ratio block, and the output of the tolerance control block is connected to the input of the measuring block,

The drawing shows a structural electrical circuit of the device.

The device contains a vibration sensor 1, the output of which is connected through an amplifier 2 and a frequency selector 3 to one of the inputs of the threshold device 4, the source 5 of the reference voltage, the input of which is connected to the output of the frequency selector 3, and the output to the other input of the threshold device, the output of which the pulse driver 6 is connected to the input of the time interval unit 7, the tolerance control unit 8, the signal input of which is connected to the output of the unit 7, and the control input to the output of the pulse shaper b and the measuring unit 9 at the output of block B tolerance control. Control inputs are supplied to inputs 10 and 11,

In the proposed device, the frequency selector 3 can be made, for example, in the form of a bandpass filter with a passband corresponding to the most intense component of the spectrum of vibroacoustic signals from certain percussion processes.

The reference voltage source 5 produces a reference voltage proportional to the average or amplitude value of the signal sequence, and can be performed, for example, in the form of serially connected detectors, an integrator and a filter or an amplitude detector and a voltage divider.

Block 7 of the time interval relationship divides each current time interval T between the remotes by two adjacent pulses by the previous T time interval.

Claims (2)

The tolerance control unit 8 compares the result of a ratio of 5 time intervals with a given value and can be performed, for example, on the basis of a reversible counter with a preset or on the basis of a counter, a memory register and a comparison circuit. The device works as follows. All systems in the engine operate in the order determined by the angle of rotation of the roller shaft. As a result, the shock processes occurring in the kinematic pairs of the engine are also ordered and, therefore, the position of the zibrsacoustic signals in their sequence at the output of the vibration sensor is ordered. The position of each signal in this sequence relative to each other is fairly stable to within several degrees of the angle of rotation. If we find the ratio of each time interval T (between two adjacent signals to the previous T time interval, for example, by dividing the intervals by each other, we obtain a sequence of division results:, - Tt / V, ... T "/ V,; TI / Tf; Lf, etc. Since the vibroacoustic signals from a certain percussion process are repeated at a frequency of a multiple of a rotational frequency, the sequence of the Ti / Tt ratios repeats with the same frequency. If these ratios are compared as they occur with a predetermined and equal to one of them, equality repeats only once per period. As a result, only one signal arrives at the measuring unit for a period that is a multiple of the rotation period, which corresponds to its specified relative position in the sequence of other signals. The vibration sensor 1, installed on the engine, produces at its output a sequence of vibro-acoustic signals. Signals of various amplitudes, durations and frequencies following in accordance with shock processes occur in the engine during its operation. A high input impedance amplifier 2 amplifies these signals and feeds them to the input of frequency selector 3. The latter filters and transmits to the output those signals whose frequency spectrum most fully corresponds to the bandwidth of frequency selector 3. Next, the vibroacoustic signals go simultaneously to one of the inputs the threshold device 4 and to the input of the source 5 of the reference voltage, from the output of which the reference voltage is fed to another input of the threshold device, which performs the amplitude selection of the vibroac -terrorist signals from the signals generated by the motor structural noise. If the signals in their amplitude exceed the level of the reference voltage, they are passed on. the output of the threshold device C and then to the forma tion of pulses 6, if they do not exceed, the output of the threshold device is not passed. The pulse former 6 of vibroacoustic signals forms rectangular pulses whose duration is shorter than the interval between signals in the sequence. These pulses simultaneously arrive at the input of block 7 of the ratio of time intervals and to the control input of the block B of the tolerance control, preparing the latter for operation. In the millisement of the arrival of the next pulse, block 7 generates at its output the result of executing the completed time interval to the previous interval i-4, while the result of dividing K. is equal to,. This result is fed to the input of block 8, in which it is compared with Two permissible values: lower K and upper Kg, which are entered into block 8 via inputs 10 and P. Block 8 produces a pulse at its output only if K " Ki Sq. If Ki is Kn or Kj, block 8 does not produce a pulse. at the moment when the next pulse arrives at the input of block 7, where the next result of relation K is produced, which also goes to the comparison in block 8. Thus, the sequence of signals at the output of the threshold device i corresponds to the output of block 7 the sequence of results of the relative intervals between these signals: К 1, / Т „-, / Ti, ... К Ti / T; i, -,, KV, TV, / T, K, Ti / Т„ .. 79 If in the sequence of the results of the relations one of results, for example, K will be within K K Kg, unit 8 will generate a pulse, The second is the measuring unit 9. Since the result of the ratio appears once in a period that is a multiple of the rotation percussion, the frequency of the pulses at the output of the unit 8 is proportional to the frequency of rotation of the motor shaft. Measuring unit 9 converts the frequency (period) of these pulses into a shock waveform. Due to the spread of one of the vibroacoustic signals, its amplitude increased and this signal exceeded the level of the reference voltage. As a result, for a period that is a multiple of the rotational speed period, the pulse shaper 6 generates a larger number of pulses per unit. An additional impulse changes the ratio of time intervals in the area of its appearance. If the additional result of the ratio does not turn out to be equal to the specified allowable value in block 8, the latter does not work and the additional pulse to measuring unit 9 does not pass and does not distort the measurement result. The device works in the same way if the amplitude of one of the vibroacoustic signals is lower than the level of the reference voltage due to throwing times. The necessity of setting the zone bounded by the lower and upper values in block 8 is due to the fact that during engine operation the time intervals T | between vibroacoustic signals may vary somewhat, for example, due to misalignment and wear of assemblies and parts. As a result, the value of K takes the form. With this in mind, at the inputs of control 10 and 11 of block 8, there is a triggering zone between the values of KH. and K 1. The K values are determined from the engine timing diagram. At the same time, of all the ratios of time intervals in block 8 of the tolerance control over inputs 10 and 11, it is best to set a value K that differs sharply in size from all other values. The application of the invention makes it possible to increase the accuracy of controlling the rotational speed by additional selection of signals according to their position relative to each other. Apparatus of the Invention A device for controlling the rotational speed, comprising a vibration sensor connected in series, an amplifier, a frequency selector, a threshold device and a pulse shaper connected between the output of the frequency selector and the second input of the threshold device, a reference voltage source and a measuring unit different from in order to improve the measurement accuracy, a time interval ratio block and a tolerance control block are entered into the device, with the input of the ratio block and the first input of the additional block Skov control connected to the output of the pulse, a second input block tolerance control unit connected to an output relations and yield tolerance control unit connected to the input of the measuring unit. Sources of information taken into account in the examination 1. NS Zhdanovsky and others. Diagnostics of autotractor engines using electronic devices. L., 1973, p. 66 2. The patent of Germany No. 1673919, - ° 1975 (prototype).