RU2291411C2 - Method of measuring nonuniformity of rotation of crankshaft of internal combustion engine - Google Patents

Abstract

FIELD: measuring technique.

SUBSTANCE: method comprises determining rotation parameter within a specified angular interval of rotation of the shaft and comparing the value of the parameter with its value in the other angular interval. The parameter represents the time of rotation, and it is compared with the time of rotation of the shaft in the subsequent angular interval. The range of the angular interval is chosen within one degree.

EFFECT: enhanced accuracy of measurements and reduced labor consumption for measuring.

1 cl, 3 dwg

Description

The invention relates to measuring equipment and, in particular, to testing, research and operation of vehicles equipped with internal combustion engines (ICE), and can also be used to diagnose the technical condition of ICE by changing the uneven angular speed of rotation of its crankshaft.

There is a method in which the measurement of the unevenness of rotation for two turns of the crankshaft of the engine at a certain value of the angular velocity recorded in advance in the storage device. In this way, from the moment the reference starts, the average angular velocity of rotation of the shaft at sixteen angular intervals of 45 ° each is determined, they are compared with the constant angular velocity recorded earlier and the comparison results are output to the recording device. Knowing the order of operation of the engine cylinders, using the recording device determine the parameters of the uneven rotation in the measurement sections for two shaft rotations [RF patent No. 2029306, m. G 01 P 3/36, 1995].

There is also known a method of measuring the unevenness of rotation, implemented using the device [and.with. USSR No. 1035521, metro class G 01 P 3/36, 1983]. This method is based on the principles identical to the method discussed above, namely, the average angular frequency of rotation of the shaft is measured and then compared with the maximum and minimum values recorded previously in the storage device.

In this way, the non-uniformity of the rotation of the shaft is measured on the angular interval reduced to 15 ° in several measurement cycles.

Common disadvantages of the known methods of measuring unevenness of shaft rotation in the considered analogues are: insufficient measurement accuracy and low sensitivity of the meters, which do not allow to determine the change in the angular velocity of rotation of the shaft or its instantaneous value within the angle of rotation of the shaft to 1 °, the great complexity of measurements and the complexity of the associated calculations , which reduces reliability and increases the likelihood of errors.

The closest analogue to the problem being solved and the technical result achieved is the method implemented using the device for controlling the uneven rotation of the internal combustion engine shaft [a.s. USSR No. 1348696, m. Cl. G 01 M 15/00, 1987].

When measuring by this method, information is accumulated on the current values of the average angular velocity of rotation of the shaft within a fixed angular interval and then the obtained value is compared with the maximum ω _max and minimum ω _min values recorded in the registers in previous measurement cycles. The unevenness of the rotation of the shaft δ is determined by calculating the parameters in the computing device according to the formula

The main disadvantages of this method of measurement can be considered a large angular interval for determining and recording the average angular velocity, which corresponds, tentatively, to ten degrees, which reduces the accuracy of the measurements; the need to use a computing device, as well as a complex algorithm for recording the current value of the average angular velocity in a particular register by the criterion for comparing the value of its code with the codes ω _max and ω _min previously measured and stored in the registers, which leads to malfunctions and errors of the calculator, moreover, the digital information storage registers proportional to the total value of the values of the angular velocity of rotation of the shaft over a relatively large angular interval must have a sufficient number of digits, the pain neck than the device should possess greater sensitivity to changes in angular velocity.

The technical result of the invention is to increase the accuracy of measuring changes in the angular velocity of rotation of the shaft, reducing the angular interval for measuring the instantaneous angular velocity to 1 °, reducing the complexity and volume of calculations when determining the parameters of uneven rotation by directly measuring them.

The solution of this problem is achieved by the fact that the primary processing of information on measuring the unevenness of rotation is carried out by comparing information for one time interval of passage of adjacent marking elements with information for the subsequent time interval by subtracting the second value from the first. Since the information is presented in the form of digital codes, the result of such subtraction is a code proportional to the increment of the instantaneous angular velocity Δω during the rotation of the engine crankshaft by one interval equal to the angle Δφ between adjacent marking elements, for example, teeth of the flywheel ring gear. Since the value of Δφ is relatively small (in modern engines it is 3-4 ° around the circumference and, in principle, it is desirable to bring it to 1 °), the increment of the angular velocity in this angular interval will also be small. This means that it is represented with great accuracy in binary code using a small number of bits (from 3 to 8). Decreasing the digit capacity of the digital information code will reduce the number of radioelements used, and therefore, increase the reliability of the equipment, improve its energy and ergonomic characteristics while reducing the overall dimensions of the control device.

Figure 1 shows the arrangement of the ring gear B of the engine flywheel with teeth 1, 2, 3, etc. and signal sensor A. Figure 2 shows a block diagram of a device for implementing the proposed method for measuring the unevenness of rotation of the shaft, and figure 3 is a plot of signals in areas of this circuit.

The invention is illustrated by the following description of the method of its implementation. First, the measurement time interval is set for a certain angle of rotation of the shaft and the increment of the instantaneous angular velocity Δω is determined for this period of time or at the end of the rotation angle of the crankshaft compared to the initial value. To do this, the entire circumference of one revolution of the shaft (φ = 360 °) is divided into separate equal angular sections Δφ, within which it is necessary to measure the increment of the angular velocity. On the ICE shaft, the rotation non-uniformity of which is measured, a measuring disk is installed, for which, for example, the ring gear of the ICE flywheel can be used. On the outer perimeter of the disk (the flywheel of the flywheel) are located control markers (teeth) at a fixed distance Δl from each other. The distance Δl is related to the value Δφ by

where R is the outer radius of the circle (flywheel crown).

Given that Δφ = const, also Δl = const.

The transit time of each next section Δl during rotation of the shaft, and hence the disk with markers, depends on the value of the angular velocity ω of rotation of the shaft over this period of time. By comparing the values of the angular velocity in the adjacent sections Δl ₁ and Δl _{2 with} each other, determine the increment of the instantaneous angular velocity (+ Δω or -Δω) in the subsequent section compared to the previous one.

The angular velocity of rotation of the shaft ω _i in each section of the circumference Δl _{i is} proportional to the travel time Δt _{i of} adjacent markers relative to a fixed fixed point (in which, for example, an inductive sensor is installed):

From this expression it follows that the value of the angular velocity in each section of the circumference Δl _i can be determined by measuring the time Δt _{i of the} passage of neighboring markers relative to one fixed fixed point. If we subtract from the transit time of the previous section the transit time of the next section, we can determine the increment of the angular velocity in the next section compared to the previous one:

From this formula it follows that to determine the increment of the angular velocity in the next section compared to the previous section, it suffices to measure the increment of the travel time τ of the adjacent fixed sections Δl ₁ and Δl ₂ taking into account the sign (+ or -).

τ = Δt _i -Δt _{i + 1}

In the case of equal transit times of two adjacent sections, i.e. Δt _i = Δt _{i + 1,} we obtain τ = 0 and the increment Δω = 0, i.e. rotation unevenness is absent.

To implement the proposed method for measuring the unevenness of rotation using the following equipment (figure 2):

- angular velocity sensor - speed (inductive sensor);

- two channels for measuring the transit time of neighboring sections Δl _i ;

- synchronization unit for the operation of time measurement channels (switch);

- information storage registers;

- computing device, the basis of which is an adder;

- an output device showing directly the uneven rotation of the shaft.

Of the known devices for measuring time and processing information, the most rational use of digital and pulse devices.

From the sensor of the angular velocity of rotation of the shaft when a marking element (marker) passes past it, a signal is supplied to the switch (synchronizing device), which directs it to the first time measurement channel. This channel measures the time in a digital code until the next pulse arrives from the sensor. The digital code is copied to the comparison node. When the shaft rotates after receiving a signal from the second marker, the switch directs it to the second time measurement channel, and in the first channel the counting is stopped. The digital code of the measured transit time of the second section is copied to the comparison node and subtracted from the recorded code of the transit time of the first section. At the same time, the same code is recorded in the register of short-term storage of information of the comparison node. With the arrival of the next marker signal, the switch redirects it to the first time measurement channel, which is previously reset. The code from this channel is subtracted in the comparison node from the code stored in the short-term storage register. The codes are written and the next one is subtracted from the previous one in turn, while from the comparison node in each angular interval of rotation of the shaft Δφ _{i, the} comparison result (value τ) carrying information about the increment of the angular velocity Δω (or rotation nonuniformity δ) is copied to the results storage register interval taking into account the sign. From the results storage register, information directly in digital code is transferred to the output device as necessary. A smaller digital code indicates less uneven rotation.

Thus, the main advantages of the proposed method for measuring the non-uniformity of rotation of the shaft are greater automation and acceleration of the process of determining the magnitude and sign of the increment of the instantaneous angular velocity in the subsequent interval of the angle of rotation of the shaft compared to the previous angular interval and the presentation of this information without complex computational operations directly in binary digital low bit code. This method can be used in modern systems for the diagnosis and control of internal combustion engines, requiring high efficiency measurement of increments of the instantaneous angular velocity of rotation of the crankshaft at a small angular interval of its rotation.

Claims (2)

1. The method of measuring the uneven rotation of the crankshaft of an internal combustion engine by determining the rotation parameter within a fixed angular interval of rotation of the shaft and comparing it with this parameter on another angular interval, characterized in that the rotation time is used as a rotation parameter and compared with the rotation time the shaft at a subsequent angular interval, and the range of the angular interval is selected within one degree. 2. The method according to claim 1, characterized in that the results of comparing time intervals are taken into account in a binary digital code.

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