RU2210068C1 - Device for measuring linear and angular displacements when diagnosing condition of vehicles - Google Patents

Abstract

FIELD: transport engineering; checking facilities. SUBSTANCE: proposed device contains measuring raster, two data readout channels consisting of lighting devices, photodetectors, signal shapers coupled with change-over switch on their multiplication by 1, 2 or 4. Forward and inverted signals of signal shapers get to inputs of signal differentiation and multiplication units at output of which they are divided to two channels of discrete displacements providing information on value and direction of displacements. Measuring raster is connected with object to be investigated by gear train with step-up gear ratio and adapted for tasking up its own by constant one-side meshing of gears regardless of direction of their rotation. EFFECT: simplified design, reduced overall dimensions and cost, improved reliability in operation. 5 dwg

Description

 The invention relates to devices for measuring linear and angular displacements in the diagnosis of vehicles and can be used in the operation of automobiles.

 A device for measuring displacements is known (ed. Certificate. USSR 1250847, class C 01 B 11/00, 1986). This device allows you to measure with high accuracy the values of angular or linear displacements (as well as the speed and acceleration of the object), using the output information of the sensor about the coordinate. But it makes high demands on the alignment of its optical components, the stability of the elements of the processing circuitry for information received from photodetectors, a complex and fragile design and unacceptably large dimensions for the purpose of diagnosing vehicles.

с пространственным сдвигом фаз на π/2. Для формирования импульсов сложения служат четыре схемы совпадения И1-И4, с выхода которых импульсы поступают на схему ИЛИ1. Для формирования импульсов вычитания служат схемы совпадения И5-И8, с выходов которых импульсы поступают на входы схемы ИЛИ2. На первые входы схем совпадения И1-И8 подаются импульсы

полученные дифференцированием положительных фронтов прямоугольных напряжений

дифференцирующими цепочками Д1-Д8, на вторые входы этих схем подаются сами прямоугольные напряжения

При движении измерительной растровой решетки в направлении (+х) на реверсивный счетчик PC поступают сигналы сложения

а при движении в обратном направлении (-х) на реверсивный счетчик PC поступают сигналы вычитания

При перемещении измерительной решетки на один шаг растра на счетчик подаются четыре импульса. Их количество уменьшится до двух при блокировании на нулевом уровне одного из инверсных сигналов

или до одного при таком блокировании обоих сигналов

Однако и такое устройство имеет ряд существенных недостатков, ограничивающих возможность его применения при диагностике автотранспортных средств: измерительный и индикаторный растры выполнены на подложках из оптического стекла и не допускают динамических перегрузок (падений), а также сложны в изготовлении. Так, например, при дискретности угловых измерений 0,1 градуса/импульс требуется нанесение на измерительный растр 900 штрихов, для чего необходимо применение специальной технологии; преобразование пространственной фазы муаровой картины в пропорциональный временной сдвиг периодического электрического сигнала требует наличия фокусирующих линз, индикаторного растра и четырех включенных по балансной схеме фотоприемников, что ведет к увеличению габаритов устройства, усложняет его эксплуатацию.The closest in technical essence to the proposed device and taken as a prototype is an accumulating reading device (Photoelectric information converters. / Under the editorship of LN Presnukhin. - M .: Mashinostroenie, 1974, p. 178-182), containing a illuminator, measuring and indicator rasters, balanced pairs of photodetectors, at the outputs of which sinusoidal signals V1 and V2 are formed, shifted in spatial phase by π / 2 and fed to the inputs of the formers F1 and F2. Each of the formers has two outputs. A rectangular voltage with the same phase as the input sinusoidal signal is removed from one shaper output, and a rectangular voltage with a phase shifted by π relative to the first is removed from the other output. Thus, four rectangular voltages are formed at the outputs of the formers F1 and F2

with spatial phase shift by π / 2. To form the addition pulses, there are four coincidence circuits I1-I4, from the output of which the pulses go to the circuit OR1. To generate the subtraction pulses, I5-I8 coincidence schemes are used, from the outputs of which the pulses go to the inputs of the OR2 circuit. The first inputs of the matching circuits I1-I8 are pulses

obtained by differentiation of positive fronts of rectangular stresses

differentiating chains D1-D8, the rectangular inputs themselves are fed to the second inputs of these circuits

When the measuring raster grid moves in the (+ x) direction, addition signals are sent to the reversible counter PC

and when moving in the opposite direction (s), the subtraction signals receive the subtraction signals PC

When the measuring grid is moved one step of the raster, four pulses are transmitted to the counter. Their number will decrease to two when one of the inverse signals is blocked at zero level

or up to one when blocking both signals

However, such a device also has a number of significant drawbacks that limit the possibility of its use in vehicle diagnostics: the measuring and indicator rasters are made on optical glass substrates and do not allow dynamic overloads (drops), and are also difficult to manufacture. So, for example, when the discreteness of angular measurements is 0.1 degrees / pulse, it is necessary to apply 900 strokes to the measuring raster, which requires the use of special technology; the transformation of the spatial phase of the moire pattern into a proportional time shift of a periodic electrical signal requires the presence of focusing lenses, an indicator raster and four photodetectors included in a balanced circuit, which leads to an increase in the dimensions of the device and complicates its operation.

 The technical result of the proposed device is to preserve the basic functionality of the prototype while simplifying the design of the device, increasing reliability, reducing the size and cost. This is achieved by the fact that the device for measuring linear and angular displacements, comprising a measuring raster, a first reading channel made in the form of sequentially installed and optically coupled illuminators, a measuring raster and a photodetector, the output of which is connected to the input of a signal conditioner, the direct and inverse outputs of which in turn, they are connected to direct and inverse inputs of a signal differentiation and multiplication unit, output 1 of which is information about a discrete positive value and output 2 is about the same negative, equipped with a second illuminator and a second photodetector in series, optically coupled to the measuring raster, and forming a second readout channel with its signal shaper, the direct and inverse signals of which are fed to the third and fourth input of the differentiation unit and multiplication of signals, and the measuring raster is connected to the measuring object by a gear train with an increasing reduction coefficient and with a tension device of one-sided forced sampling ftov meshing gear pairs, regardless of the direction of movement. The second readout channel introduced into the device instead of the second balanced pair of photodetectors, including a illuminator and a photodetector with a signal shaper, the optical axis of which is offset along the circumference of the raster divisions by (n + 1/4) of the raster grid step from the optical axis of the first channel, serves to obtain unipolar rectangular duty cycle signals 2, shifted in spatial phase by π / 2 relative to the signals of the first channel and forming together with them a signal system for the unit for differentiation and multiplication of signals.

 The introduction of a gear train for connecting the measuring raster with the measurement object allows you to significantly increase (roughen) the pitch of the raster grid while reducing the diameter of the raster disk, abandon the indicator raster, focusing lenses (capacitors) and balanced pairs of photodetectors, reduce the dimensions of the device, and make the raster disk itself metal. In this case, the linear movement of the measured object is converted by gearing into the rotational movement of the measuring raster. The prototype does not have such a need, because the device is placed at the end of the lead screw (backlash-free connection) with a known step, which is converted during rotation into a certain number of discrete pulses of linear movement. A tensioning device that creates preliminary unilateral gearing of gear pairs, regardless of the direction of their rotation, is designed to eliminate the main part of the gear play when the measured value is reversed.

 The measurement error from the remaining part of the backlash, which is long constant for a particular device, is compensated by the electronic correction input circuit (see the technical description of the application reg. 2002100029 of January 4, 2002, pages 13, 14, 18-21).

 Figure 1 presents a functional diagram of a device for measuring linear and angular displacements; figure 2 - device gear with a measuring raster; figure 3 - arrangement of illuminators and photodetectors of photodetectors on the grid of the measuring raster; figure 4 - circuit diagram of the device; figure 5 - graphs of stresses at various points of the device.

со вторым и четвертым входами блока 10 дифференцирования и умножения сигналов.The device comprises (Fig. 1) a measuring raster 1, gear 2, two reading channels, consisting of illuminators 3 and 6, photodetectors 4 and 7, the outputs of which are connected to the first inputs of the shapers 5 and 8, the second inputs of which are connected to the switch 9 coefficient multiplying pulses by 1, 2 or 4. Direct outputs of the signals 1T and 2T of the shapers are connected to the first and third, and the inverse

with the second and fourth inputs of block 10 differentiation and multiplication of signals.

 The gear 2 (figure 2) for measuring linear displacements contains a gear measuring rack 11 with sliding bearings 12 and 13, which engages with the first stage of the double gear 14, the second stage of which is meshed with the gear 17 of the drive of the measuring raster 1. Engaged the same gear consists of the gear of the tensioner 18 with a drum 19 for winding the cable and a spring 20. The gear transmission for measuring angular displacements is characterized by the absence of a measuring gear rack 11 and bearings 12 and 13, and the measured value is fed directly to the shaft 16 of the first gear 14 of the gearbox.

 The optical axis (Fig. 3) of the optocouplers 3-4 and 6-7 (illuminators and photodetectors) are mutually offset along the center line of the circle of the raster lattice by (n + 1/4) of its steps, where n is an integer number of steps.

Далее эти сигналы поступают на входы соответственно 1, 3 и 2, 4 блока 10 дифференцирования и умножения сигналов, состоящего из микросборок А7 и А8 (фиг.4), на которых происходят выделение их передних фронтов и формирование на их основе двух новых, учетверенных по отношению к исходной частоте, серий импульсов Т1 и Т2, разделенных по направлениям перемещений. Их формирование происходит по функциям

Здесь приставка И означает дифференцирование сигнала на емкостно-резисторной цепочке при подаче на вход микросхемы (фиг.4). При этом величина резисторов R7-R14 должна быть такой, чтобы при отсутствии сигнала или окончания заряда емкости на входе микросхемы был уровень логического нуля. Для микросхем серии К555, использованных в устройстве, они приняты равными 560 Ом. Коэффициент умножения 4 (положение П1/3 переключателя 9 фиг.4) снижается до 2 при блокировании одного из инверсных сигналов

на нулевом уровне (положение П1/2 переключателя на 9 на фиг.4) или до 1 при положении переключателя П1/1 и блокировании обоих инверсных сигналов

Сигналы Т1 и Т2 строго разделены по направлениям перемещения соответственно +Х или -X (фиг.4). При наличии Т1 обязательно отсутствие Т2 и наоборот.For design reasons, the number n should be the smallest possible to reduce the influence of inaccuracies in the fabrication of the measuring raster on the mutual offset of the readout channel signals by π / 2.
The device operates as follows. The gear transmission turns the rotational or translational displacement of the measured object into the rotational movement of the measuring raster, modulating the light flux incident on the photodetectors. At the outputs of the photodetectors 4 and 7 (Figs. 4 and 5), unipolar pulses 1T and 2T of duty cycle 2 are formed, shifted in space phase by π / 2. Signal conditioners 5 and 8 give these signals with steep fronts, and also generate their inversions

Further, these signals are fed to the inputs 1, 3 and 2, 4 of the block 10 for differentiation and multiplication of signals, consisting of microassemblies A7 and A8 (Fig. 4), on which their leading edges are selected and two new quadruples are formed on their basis relative to the initial frequency, the series of pulses T1 and T2, divided by the directions of movement. Their formation occurs by function

Here, the prefix And means the differentiation of the signal on the capacitor-resistor circuit when applying to the input of the chip (figure 4). In this case, the value of the resistors R7-R14 should be such that in the absence of a signal or the end of the charge of the capacitance at the input of the microcircuit there should be a logic zero level. For the K555 series chips used in the device, they are taken equal to 560 Ohms. The multiplication factor 4 (position P1 / 3 of the switch 9 of figure 4) is reduced to 2 when one of the inverse signals is blocked

at zero level (position P1 / 2 of the switch at 9 in Fig. 4) or up to 1 at the position of the switch P1 / 1 and blocking both inverse signals

The signals T1 and T2 are strictly separated in the directions of movement, respectively, + X or -X (figure 4). In the presence of T1, the absence of T2 is necessary and vice versa.

 Using the proposed technical solution allows the manufacture of devices (sensors) for discrete angular and linear movements for the diagnosis of vehicles of acceptable dimensions, resolution and measurement range.

 Thus, a device for measuring linear displacements, made in a artisanal way, has a rectangular case with dimensions of 25x30x86 mm with a measuring raster diameter of 25 mm, a resolution of 0.05 mm / pulse and a measuring range of 0-20 mm. A similar device for measuring angular displacements, made in a round case with a diameter of 64 mm, a height of 32 mm and a diameter of a measuring raster of 27 mm, has a resolution of 0.1 angular degrees / pulse and a measurement range of ≈720 angular degrees, and a control device made in the same case microdisplacement has a resolution of 0.0025 mm / pulse with a range of 0-10 mm. In this case, the own residual backlash of the devices does not exceed 2 discrete movements. If necessary, the discreteness of devices, for example, 0.0025 to 0.0050 or up to 0.01 mm / discrete, can be changed by changing the multiplication factor.

 When diagnosing vehicles, these devices can be used to determine the steering wheel play, determine the total play of the steering gear and pivots, the convergence of the front wheels, the angle of the closed state of the contacts of the mechanical breaker of the ignition system, to measure clearances when adjusting engine valves, etc.

 The use of devices for measurements at other objects is significantly limited both by their range and by the inertia (speed) due to the presence of a step-up reducer, adaptation of a selection of backlash and a measuring rail.

Claims (1)

 A device for measuring linear and angular displacements in vehicle diagnostics, comprising a measuring raster connected to an object, a first reading channel made in the form of optically coupled illuminator, a measuring raster and a photodetector, the output of which is connected to the first input of the signal conditioner, the second input of which is connected to the first output of the signal multiplier coefficient switch, while the direct output 1 of the signal shaper is connected to the first input, and its inverse output 2 is connected to the second input m unit of differentiation and multiplication of signals, outputs 1 and 2 of which are information on the magnitude and directions of movements, characterized in that it is equipped with a sequentially mounted and optically coupled second readout channel, including a illuminator and a photodetector connected to the first input of the second signal conditioner, the second input which is connected to the second output of the signal multiplier coefficient switch, while direct output 1 of the second signal conditioner is connected to the third, and its inverse output 2 s it is single with the fourth inputs of the signal differentiation and multiplication unit, and the optical axes of the first and second reading channels are spaced along the axial circumference of the raster divisions with a mutual spatial shift of their output signals by π / 2, / while the measuring raster is connected to the object by a gear transmission with an increasing reduction coefficient and permanent unilateral gearing of the gear pairs under the action of the tensioner of the backlash selection.

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