DE1673386A1 - Measuring device for measuring speed, in particular of vehicles - Google Patents

Description

1/21397 October 7, 1968 Χΐ / Dl

P 16 73 336.1

Franz Valentin Gebart, Lyttelton, Pretoria, 198 Monument Ave

South Africa

Measuring device for speed measurement, in particular of Vehicles

The invention relates to a measuring device for measuring the speed, in particular of vehicles, on a measuring section of known length by means of a time measuring device activated by a start pulse generator at the beginning of the measuring section and stopped by a stop pulse generator at the end of the measuring section, the start and stop pulse generators responding to the wheel pressure respond, if necessary with pulse amplifier devices and electronic main gate. In a known measuring device of this type, the start or. Stop pulse generated by pulse generators arranged one behind the other in the direction of travel at a distance from the measuring section. This known device is mainly used to eliminate the human inadequacy in operating a timing device such as a stopwatch. Attempts have also been made to operate a timing device by the impulses of photocells which are arranged at the beginning and at the end of a measuring strip of known length. The impulses of the photocells are generated by the fact that at the beginning and at the end of the measuring section a light beam directed across the roadway onto the respective photocell is interrupted by the passing vehicle. Although this known method is theoretically very accurate, <*>, however, occur in practice significant inaccuracies that exclude ^ an exact measurement of the world as possible. The main reason for the inadequacy of this known method is that the vehicle does not have the same location as the one existing there when entering the test section

Light beam interrupts, even if the vehicle is located, Urrt «rl * S * ⁿ <*«. / § 1 Abi. 2 Kr. 1 sentence 3 of the amendment v, 4.1.1W7)

aia Lnde dor Mosbahn dia interruption dos there existing light beam caused. This is before everyone on the often significant unevenness of the road surface, dio causes the vehicle to go up and down vlppt, εο that beisi entering the tfesstrccka of there existing light beam, for example, through much protruding Ltofstangenhtfrnor of the vehicle underbrochon while the light beam is due to the end of the measurement path a rocking movement of the vehicle only through v / oiter zurtielictohcnde body part of the vehicle interrupted vird. This is also the l'all when the rays of light fail arranged at exactly the same height above the road surface are. A precise adjustment of the light beams to the However, the surface of the wagon is relatively difficult because the Beams of light, especially when the barrel is bright, is multiple can only be seen very indistinctly, i.inngoniüis that the same also applies to the arrangement of the light beams at a precisely defined distance in the direction of travel. Besides that there is a risk that the measurement will be falsified by reflective surfaces such as chrome parts of the vehicle vird. These may reflect a lonnon beam ^ in such a way that he meets one of the photo lines and thereby temporarily replaced the assigned light beam so that it is registered as not being interrupted by the measuring device vird. As a result, it corsets with this well-known In practice, this often leads to fine measurements, the results of which differ to a considerable extent from the actual, the driven speed differ.

With a measuring device operated by wheel pressure The above-mentioned sources of error do not occur. In a known device of this type is the x ^ tart- birw. the itoppiapuls for the timing device of two air gauges ~ hlä * uchon generated, dio at the beginning and at the south end Mos section across above the lane are laid. The impulse With this device, the door is rolled over caused by the Effdorn dos Fahrzeuges. Here,

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inside each; chlauchos there is a pressure wave that is used to trigger a pressure switch »This method is also imprecise, one reason being that the pressure switches are mechanically operated devices that require a relatively long period of time to respond, which also depends on the Hiring and the status of the liembranen assigned to them is permissible. On the other hand, the propagation of the pressure wave needed within each hoses s verhä'ltnisna'ssig a long period of time, which also is still dependent on which temperature has the air in dom respective ι chlauch, said leg Ltartinpulsgober uecontlich due to different temperature of the Fahrbahnoberflä'cuo This can be different than when the top-pulse transmission is outside, because when entering the route the vehicle rolls over the hose at a point nearer to the assigned pressure switch than when it is exiting the route. As a result, the distances which the pressure wave has to traverse in the individual i chla'uchon in order to reach the pressure class are of different lengths, which also has a detrimental effect on the accuracy of the results, especially since the speed of propagation of the pressure wave is relatively slow and only at about 330 m per second. In addition, it is practical (due to leap temperature fluctuations) to keep the response times of the two mechanical pressure switches for the start and / or top pulse completely uniform with the required high level of accuracy, so that an exact solution with this known method is not possible. This does not work even then, venn's "Electronic Engineering", Jebr. 1958> ^ eito 77 use is made of electronic switching and switching circuits, as this does not eliminate the risk of malfunctions and imprecise mechanical switching elements. Air hoses cannot easily be provided with the required accuracy and

ür.tu, ί jguiI (AiJ.Q 9 $ 32 $ lyi0 ^ g ^ s changes from A: 7.1967)

BATH ORIGINAL

roll u \ x £ the wtrassenoborflii'che. With Lurtsehi &'ucJron · it is only swore or not possible to switch off with certainty the Ctörlcipulse generated by I <' U £ sg3ta- '\ yarn, Fjhrra'dern or dorgl. Out of order, the sudden pressure waves that occur during air travel can also result in repeated actuation of the switch.

The invention has set itself the task of creating a device which does not adhere to the disadvantages dealt with above and which enables largely exact measurements independently of the ever-wavy Xeraperatur of the road surface and other influences and provides a legally unimpeachable overall result, According to the invention, the object is achieved in that the start and stop pulse generators each consist of a pair of loops with a piezoelectrically sensitive insulating layer in between and any devices for amplifying piezoelectric impulses are set up. be accurately generated and itoppimpulse completely independent of all eonstigen V influences in the moment in which "the Ka'der of the vehicle at the beginning or at the roadway angeordnetenlmpulsgeber Knde of Mo c ii tr corner transversely, in particular screened cables, roll over. Since the instantaneous or stopping impulses include electrical impulses, which are known to propagate at an extraordinarily high speed within the cables and within the boiler, there is practically no time delay and, in particular, no time delay for the litart * and itoppimpuls Transmission of the impulses from the cables to the measuring device on * Ausordom is the extraordinarily high amount of gas with which these impulses are propagated, regardless of all; external flows, such as, for example, the temporal door,, always the same. As a result, foalities which can be traced back to a different transmission speed of the impulses to the measuring device are completely

WHEEL-

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locked out. In addition, in the device proposed according to the invention, the impulses are always generated at the moment "when the vehicle assumes a very specific position in relation to the cables delimiting the measurement path" namely at the moment "at which the wheels of the vehicle set the pulse generators, eg cables , roll over. The first start or stop pulse in each cable is thus always triggered by the front wheels of the vehicle, which ensures that the same point of the vehicle always triggers the first pulse and incorrect measurements, as in the known device with photoelectric cells, are excluded. Further sources of error are eliminated by the fact that, according to a further development of the device and due to the extraordinary accuracy, it is possible and suggested to keep the pulse generators always at a precisely defined distance, which is certainly smaller than the center distance of the vehicles to be measured. A failure of the start triggering due to a front wheel jump cannot lead to incorrect measurements. The electronic main gate, which works independently of mechanical switching elements and which has the task of applying standard frequency signals to an electronic counter from the moment of the start pulse and of preventing the application from being applied from the moment of the stop pulse, works much more precisely and faster than the best mechanical ones As a result, when an electronic main gate is used, the counter is activated practically at the same instant that the front wheels of the vehicle roll over the cable located at the beginning of the measuring section the start pulse propagates and completely ruled out due to the instantaneous response of the electronic main gate. By analogy, the same applies also for the stop pulse and for stopping the counting mechanism, which gesc also without Any delay As a result, there is between

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Lciien ά · 2ζι C.-Tnea and ..closed the main author a very precise period of time which, independent of all external influences, is very accurately equal to the time the vehicle actually took to drive through the Distance required and which can be precisely determined or read off immediately on the basis of the number of standard frequency signals on the counter

Possible legal objections to the results are preferably eliminated by that the two pulse generators with their respective associated -troalcreisen exactly the same, i.e. as identical Are pair-trained.

In the device proposed in accordance with the invention, after the first pulse, further ItartispulGO are generally kept away from the electronic main gate by an electronic security gate until a new measurement is initiated. This has the advantage that the influence of the following Eä'der of the vehicle to be measured, which are not arranged on the front axle, and the influence of the following vehicles can therefore only reach the electronic main gate with only one pulse, namely the first pulse and influence this in such a way that the standard frequency signals can get to the counter If the front wheels of the vehicle to be measured fail the cable which is located at the end of the road and which gives the pulse, so that the main gate is closed and no standard frequency signals are left to the counter It is completely impossible that the main gate will be reopened again when the cable that gives the impulse is driven over by the baths of the vehicle to be measured further behind or by following vehicles, thereby falsifying the heating . Since this safety gate is also an electronic gate, no time delay occurs here either, so that the invention.

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g "device hiorduroL in. its high accuracy is not bcaiiroriivihiEt.

after another Kerkaal dor invention will be after However, a reset pulse lasts as a zoom mechanism serving counter on liull and the electronic one ilauptgattcr covie dus electronic ^ .ickerheiusgatter switched back to wes & readiness for the next mossung. Switching back or triggering the Ettckstclli; upulses for the purpose of this is done from overland by means of üinos iirucküchaltors, the oü when the door smells er-6'jIicUt, the GcccUv ^ ndiskoit any arbitrary, even in einaii / ahrüGugstroa driving i-'ahrseugos exactly i.u nesccn.

! • 'erner itt ea ciapfehlcn ^ worth because £ i. only those. · tartb *: w. wtoppiir.pul £ .Q, dlo a pre-busimnite minimum tension own, forwarded to an electronic main gate wordon. It is also beneficial if everyone who passes by is atQ i-iinde st ttart-bi- ¥ with tension. ... top pulse before doia Lincritt in the electronic liauptgotter respectively to a pulse with an angular, preferably about right-angled voltage curve is reshaped, according to another Improvement of the finding t / is every angular ^ tart resp. itop ^ inpuls before entering the electronic liauptgatuer cu an impulse of the same, predetermined Period of e.g. 100 milliseconds, transformed »Hereby one achieves that the impulses with which the electronic Hauptgattor is acted upon, stead.s largely are designed in the same way, so that disturbances 'in the' Function of the main gate are not to be feared. Besides these measures create utter impulses as they * for example by crossing the inpulsgebendon Cables from squad drivers or by stepping on the cables generated by! - 'ussgSLger are switched off.

In general, it is recommended that the electronic security gates and dos electronic Uauptgatterfi as well as the crystal oscillator ^ and the als Timing device serving counters' Xestimpulse alt

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known period via a mechanical oichurity scatter on d: .i. electronic .. safety control b ^ w. electronic main gate too. give. The to testiapulses are more expedient; they are also resolved manually by means of a pressure switch. ..they own in a similar way as the. tuniL.rdfrcquenzsignule a precisely measured period, known in its size. When the pressure switch is actuated, the counter must display a certain known number of pulses; if this is the case, the device works properly, while otherwise any ..itb * run- ^> i'en of the electronic security goods, the electronic main gate, dos Crystal oscillator or the counter are present. In this way, a precise test of the boiler and its measuring accuracy is possible at any time without any special measuring devices.

As a rule, it is advisable to amplify the start or top impulses resulting from the piezoelectric effect of their transmission and transformation by means of an amplifier. Above all, this ensures that the Ltart or *, top _r impulses, which lose energy when they are forwarded to the main gate and during the transformation carried out on this V.ege, are not too weak when they reach the electronic main gate. In addition, it is advantageous to use a similarly designed electrical circuit for amplifying, shaping and conducting the wart and toppira pulses up to and including the electronic main gate. This ensures that the start and top pulse need absolutely the same - albeit extremely short - time to get from the cable to / to the electronic main gate. In addition, in this ^ aIIe the intensity of both the ^ tart and the i> t op ^. impulse it is exactly the same at the main gate.

In this boiler system, in contrast to the known measuring systems, the start and top pulses are electronically generated, transmitted, transformed and evaluated. Since the speed at which electrical impulses are passed on is about 3 χ 10 m / sec. amounts, these impulses become extraordinary after they are generated.

) 3 * 6? 0 * 2

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! cursor ~ eit (fbortiittolt, reshaped and upgraded. The time required for this is so short that the measuring device according to the invention is suitable for all purposes which can be practically applicable. The preferred crystal oscillator is the heating device, which is the standard "Froquonzsignale from z, 3. I) ^ H ₂ generated, which are counted directly by the counter, has a maximum error rate of O, GG? In the worst case, the main electronic gate may have an error which may result in up to half an amount per license. The chlorine of the other parts of the measuring device are also extremely messy and practically completely irrelevant. If one can add up all possible errors of the individual parts of the measuring device, then if one has one length of 1.? M and one The speed to be measured is ΙυΟ kn / wtd. based on a maximum i'chlerrnöglichkoit of otva 0.1G;> ^, which with the mentioned values of 0.18 ^ loa / hour. was met. If the speed of the vehicle to be measured is lower, the maximum possible error is also lower. 'The reason for this is that the measured time required by the vehicle to pass the measuring route is longer, while the possible error in the measuring device remains constant. A further advantage of the inventive device is that it is completely independent of the prevailing temperatures and all other identifying factors.The measuring device allows itself to be particularly difficult in such a way that it can itself works flawlessly under extreme temperature conditions of about -35 ° C to about + 75 ° C - apart from the aforementioned, extremely low and in practice completely insignificant throat possibilities "

In v / pus. Embodiment of the invention is between dom itartimpulsgebor and the electronic Hauptgattor a trained also as bistabilor multivibrator, depending LIQS & ung only a single i tar timpuls-passing elec-

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Tronisohes security gate provided. This security gate thus - as already mentioned - keep the influence of others Vehicles or wheels other than the front wheels of the same vehicle to be measured by only a single impulse, namely the first, to the electronic main gate, regardless of how much further impulses after the first nooh be received. A bistable multivibrator is best suited for this, which is constructed in such a way that that it only allows an impulse to switch from one stable state to another stable state * Es However, it is also possible to use an electronic safety toggle switch instead of a bistable multivibrator to use so-called "flip flop".

It is also advantageous between the start pulse generator and the stop pulse generator on the one hand and the electronic security or main gate on the other hand one To arrange pulse amplifier * It has proven to be useful if the pulse amplifier is used as an anti-interfering pulse largely insensitive pulse amplifiers that only amplify pulses of a certain polarity are formed is * A pulse amplifier designed in this way amplifies Im essentially only the measurement pulses generated by the wheels of the vehicle to be measured, while weaker interference pulses, for example, when pedestrians step on the pulse generator or caused by being run over by cyclists are not amplified from the outset, but rather suppressed * It is also advisable to switch between each pulse amplifier and the electronic safety or main gate switching off a glitch. Start and stop impulses to form a Reohteo wave and to a predetermined one Voltage (of 3 volts, for example) limiting, as a Sohmitt trip circuit trained pulse shaper * The voltage of each start or stop pulse is increased limits a standard value in order to switch off social influences on the electronic sloherity or main gate.

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In addition, those mentioned above are advantageously used Interference pulses that have passed the upstream pulse amplifier are switched off, so that an impairment the measurement is therefore not to be feared.

In general, it is advantageous to be between each pulse shaper and the electronic security or main gate giving each start or stop pulse a constant, predetermined period of e.g. 100 milliseconds, to be arranged as a monostable multivibrator second pulse shaper. Such a second pulse shaper is not absolutely necessary, but advantageous in that - if provided - the electronic security gate and the main electronic gate always with pulses not only the same voltage, but also more constant Perlode will be acted upon, which relates to the »function of this Gatter and also has a favorable effect with regard to their calculation and design. Although one preferably has a period of about 100 milliseconds, it is, however, easily possible to work with a different period. A while this period of for example 100 milliseconds penetrated, accidentally caught or in the circuit interspersed interference would have no effect. '

In an expedient embodiment of the invention is a monostable multivibrator both via and bypassing the electronic security gate trained, preferably manually switchable, generating constant pulses of known period Test pulse generator connected to the main electronic gate. This test pulse generator generates pulses with a period of for example 55.5 milliseconds, the period being observed with a very high degree of accuracy. However, it can of course also with impulses from another, relatively short one

Plank ues period to be worked. During the first / test pulse of the test pulse generator through the electronic security gate on

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the electronic main gate is managed and this opens, so that the standard frequency signals of the crystal oscillator can act on the counter, the second edge already acts of the test pulse, bypassing the electronic security gate, directly to the main electronic gate and closes this again, so that the standard frequency signals of the crystal oscillator the main gate can no longer pass and the counter stops as a result. Because the distance between The first and second edge of the test pulse is the same and is known due to the design and test attempts, it must The counter always shows a specific constant number of standard frequency signals. If this is not the case, so there is a fault in either the electrical safety gate, the main electrical gate, the crystal oscillator or the counter. However, such a disturbance is unlikely to occur fear that these are facilities, which are practically not subject to wear and tear and which are against mechanical and other influences protected within a housing are arranged.

It is also useful if both the test pulse generator and the start and stop pulse generator are included their downstream amplifiers and pulse formers via one preferably manually operated, mechanical safety gate to the electronic safety gate or electronic Main gates are connected. This mechanical security gate has the task of measuring and testing exactly to separate from each other. This means that it

.einerceits
What is more, it is not possible to falsify the measurement during the measuring process by unintentional touching of the test pressure switch, and that on the other hand it is also impractical to persevere in the test process by starting or stopping impulses from the pulse generators.

In a further embodiment of the invention, the counter serving as a time measuring device is connected to the electronic counter Main gate and to the electronic security gate

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a reset pulse generator designed as a monostable multivibrator, preferably one that can be held by hand, is connected. This reset pulse generator sends out pulses with a period of, for example, 2.9 milliseconds, but this period can also be selected as desired within a wide range. The HUokstellimpulse are necessary in order to be able to unblock the electronic safety gate against the start impulses at any time and to bring the closed electronic main gate back into a state that allows it to be reopened with the help of a new start impulse will. In addition, it is necessary to reset the counter serving as a time measuring device to zero after a measurement has been made and read. This reset circuit is expediently switched on or off by a push button switch or a similar contact, where- _: > by the readiness of the measuring unit according to the invention to measure. preparation for a further measurement. Before this has happened, the counter cannot be activated again by a new start pulse because the electronic security gate does not let this start pulse through. The stop impulses, on the other hand, are generally not sent to the main electronic gate via an electronic safety gate. This is not necessary because only the first of the incoming stop impulses can sohlessen the electronic main gate, while further incoming stop impulses already find a closed electronic main gate and are not able to change the existing state. It is therefore by no means disruptive if stop pulses generated by the rear baths of the vehicle being measured and / or the following traffic are applied to the electronic main gate after the measurement has taken place. In this state of the electronic main gate, they cannot produce an effect influencing the measurement.

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Bel an advantageous embodiment of the invention is the counter serving as a time measuring device from several designed as bistable multivibrators, preferably Formed decadic counting units that are sequentially in the manner of a cascade counter. This ensures that the displayed measured values are displayed in decimal places and the reading is easier Way possible 1st. Other than decadic counting unit ei! However, they would also be possible, but as a rule they are not very useful for reading because they require a cumbersome conversion require. If one uses a crystal oscillator, the standard frequency signals with rectangular characteristics and generated at a frequency of, for example, 10 kHz, so the counting units of the cascade counter count the directly Ten thousand el. Thousandths, dog rushes el, tenth, one, ten, Hundreds, etc. of an S & unde. So that means that the With such a crystal oscillator, counting units count and display seconds or fractions of a second directly and thus precisely indicate the time that the vehicle to be measured takes required to pass the measuring section having a known length. Usually you need four such, counting units consisting of bistable MuIt! vibrators that through controlled feedback circuits, the number of Divide the number of impulses by 10. The counting units are connected in such a way that each counted pulse is assigned one measuring current increased by a step of e.g. 20 microamps. The maximum limit of a counting unit is 9 levels, while the 10th pulse causes the current to be measured to go back to zero and also the downstream Counting unit a pulse is transmitted.

According to a further feature of the invention is an ammeter as a display device for each counting unit, Preferably a milliammeter with a mechanical zero point is provided. These ammeters show at the end of the measuring process indicates the final state reached or the final stage reached of each counting unit, [since the

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The current flowing through the ammeter is a measure of the process is the pulses counted by the counting units. In the case of a crystal oscillator, for example, the standard frequency signals generated with a frequency of 10 kHz, and a decadic counter, it is possible to adjust the scale of the To calibrate ammeter directly in garbage, hundredths, tenths of a second, full seconds, etc. This is also possible if the crystal oscillator instead of oscillations of 10 kHz, for example square waves of 1 kHz or of 100 kHz would generate. Is the time the vehicle to be measured to the Has to pass the measuring section, so can - since the measuring section is also known and always expedient the same size is chosen - calculate its speed in a simple way or what more expedient and faster is to be read from the prepared tables.

As a rule, it is advantageous to have a second counter next to the start or stop pulse generator for counting to connect the start or stop impulses. In this way regardless of whether the speed of one or more vehicles is measured, the number of passing vehicles Detect vehicles. Thus, the measuring device proposed according to the invention is not only suitable for measuring the speed of a vehicle, but also to measure the traffic density.

In an expedient embodiment of the invention, they exist as a start or stop pulse generator Serving cable from a surrounded by an insulating layer made of a polymer, for example a polyvinyl chloride Center conductor, which, together with the insulating layer, is covered by a coaxially arranged metallic shield and is enclosed by an outer insulating and protective layer. The shield serves as the second Conductor strand on top of which is made of a polymer

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Isolation layer rests. This insulating layer or its molecular structure causes the piezoelectric effect, namely through the mechanical pressure * that then arises, when the wheel of a vehicle rolls over the cable. The electrical impulse created in this way is carried through the cable fed to the measuring device. The voltage of this electrical pulse is around 20 to 200 millivolts, depending on the speed and weight of the vehicle to be measured.

It is advisable to run the cables used as start and stop pulse generators at their end sections Fasteners, such as steel nails, on the roadway to be attached and by spring means in tautly To keep state. This achieves that the start or. Stop pulse generator from the wheels of the vehicles can be shifted or even carried away. In addition, it is only possible with the help of a tightly tensioned start resp. Stop pulse generator maintain a measuring section which has an exactly predetermined length. It is advantageous to if the cables used as start and stop pulse generators are always kept at a fixed distance from the spacer Keep a distance that is smaller than the center distance of the vehicles to be measured. To do this, one chooses, for example a distance of 1.5 m, which must be maintained with an accuracy of about 0.1 #. This is required in order to to utilize the high measuring accuracy of the actual measuring device and not to falsify the measuring result by an imprecise dimensioning of the measuring section. One serves such spacers, it is relatively easy to use the cables as start and stop pulse generators in this way to be interpreted that the measuring section actually has a length of, for example, to an accuracy of about 1 to 1.5 mm 1.5 m. Of course, other measuring path lengths can also be used, but it is advisable to use the In any case, the measuring distance should be shorter than the center distance of the vehicles to be measured. The latter has the advantage »

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that the front wheels after they drive over the start pulse generator have already run over the stop pulse generator before the following wheels touch the start pulse generator. In normal cases, it would not do any harm if the rear wheels of the vehicle to be measured once again Give the start impulse before the front wheels have passed the stop impulse, as only the first start impulse reaches the electronic main gate and no further start impulses from the electronic security gate are allowed through will. It is better, however, to have such annoying irar pulse off from the start if possible. A particular advantage of this short distance between starting and stop pulse generator is to be seen in the fact that even if the front wheels of a vehicle to be measured skip the start pulse generator due to high speed and large unevenness of the roadway and thus no ' Giving a start impulse, the measurement is in no way falsified when - which is to be expected with certainty - the wheels trigger the start pulse of the following axis. In this case the front wheels are already over the stop pulse generator driven out before the wheels of the following axle have reached the start pulse generator. The one from the front wheels The generated stop impulse is ineffective because the main gate is still closed because no start impulse has yet been issued. The counter only starts running at the moment when the rear wheels trigger the start impulse. This will only be done again switched off by the stop impulse triggered by the wheels of the rear axle, since the wheels of the front axle are already drove past the stop pulse generator before the start pulse of the rear wheels. If, on the other hand, the distance between the pulse generators were greater than the distance between the axes of the vehicle to be measured, in this case the start impulse would come from the wheels the rear axle and the stop pulse are given by the wheels of the front axle, which completely eliminates the measurement would be unusable. / Although the measuring device after the Invention with an extraordinarily large one, all previous

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comparable measuring devices by far superior measuring accuracy works, it is extremely small and also has a relatively low weight. The measuring device according to the invention can therefore be accommodated in a housing of relatively small dimensions that easily fits in a briefcase and is therefore light and easy to use. This means an extraordinary one Improvement compared to the previously used for measuring the speed of vehicles. Measuring devices, which have many times larger dimensions and mostly only in larger vehicles, such as in Minibuses, could be installed.

The invention is illustrated in the drawing using an exemplary embodiment »It show;

Fig. 1 shows a road section with the inventive Measuring device for a roadway;

Fig. 2 shows a sonity along the line II-II of Fig. Ij

3 shows a cross section through a start or stop pulse generator;

4 is a circuit diagram of the measuring device according to FIG the invention.

The road section 1 shown in FIG. 1 is divided into two lanes 1 a and 1 b by a center line 2 consisting of broken line sections. In addition, a passenger car 5 is shown driving on the right-hand lane Ib in the direction of travel. A start pulse generator 4 and a stop pulse generator 5, which is arranged exactly parallel to it, are designed at a distance from one another that is smaller than the distance between the strikes, perpendicular to the direction of travel of the passenger car passenger car 3 and fled m belauft in the illustrated exemplary embodiment in exactly 1.50. the distance between the pulsers h and 5 over the entire length thereof by spacers 6

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kept the same size, consisting essentially of flat strips au3 consist of wood, metal or plastic and are functional the lane Ib are arranged so that they are from the vehicle wheels not be run over. The pulse generators 4 and 5 are at the end section facing the road with help of clamps 7 and nails 8 firmly connected to the track Ib. The end sections of the pulse generators 4 and 5 facing the roadside are on the roadside via spring means 9 attached. The spring means 9 hold the pulse generators 4 and 4 in a tightly tensioned state, while the spacers 6 the pulse generators 4 and 5 with an accuracy of about 0.1 # keep at a predetermined distance. The pulse generator 4 and 5 are connected to a measuring device 10, which in all Usually designed as a portable measuring device arranged in a stable housing of relatively small dimensions.

The arrangement described above is shown in section in Fig. 2, where clearly the mounting clamps 7 and the nails S can be seen. However, it is quite possible to use the pulse generator 4 and 5 in other ways to secure the road surface or to keep it at a predetermined distance.

In Fig. 3 a cross section through one of the pulse generator 4 or 5 is shown. Each of these initiators 4 or 5 has a central conductor 11, which is of a Insulating layer 12 is enclosed. This consists of a polymer, for example a polyvinyl chloride, during the Center conductor 11 is preferably made of copper or some other material that conducts electricity well. The center conductor 11 and the insulating layer 12 is encased by a metallic shield 15, which is made in a general manner from a metal mesh. The shield 15 is of an outer insulating and protective layer 14 enclosed, although elastic. But against mechanical and chemical Stress is largely sensitive.

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The circuit diagram shown in FIG. 4 shows the circuit of the measuring device 10. In this circuit diagram, 4 again denotes the start pulse generator and 5 denotes the stop pulse generator. The impulse that arises in the start impulse generator 4 when it is driven over as a result of the piezoelectric effect is first passed to an amplifier 15, which '_; for example, has a gain factor of 400. This amplifier 15 is designed so that only pulses of a certain polarity and a certain minimum strength are amplified by it. These amplified pulses pass from the amplifier 15 into a pulse shaper 16 designed as a Schmitt triggering circuit, which forms the pulse into a square wave and limits it to a predetermined voltage of, for example, approximately J> volts. This is necessary because the start pulses coming from the start pulse generator 4 are very different and have a voltage of around 20 to 200 millivolts. These very different pulses are amplified by the amplifier 15 with a gain factor of 400, for example, so that it is necessary to provide a uniform voltage limitation. In addition, the pulse shaper 16 has the task of holding out interference pulses.

In the exemplary embodiment shown in FIG. 4, the first pulse shaper 16 has a second pulse shaper 17, which is a monostable multivibrator and each start or stop pulse has a constant, predetermined period of e.g. 100 milliseconds gives. However, this second pulse shaper is not absolutely necessary. It is therefore also possible without get by with this second pulse shaper 17. ·

From the second pulse shaper 17, the start pulse is sent to a mechanical safety unit via a line IQ. gate 19 supplied. This mechanical security gate the stop pulse of the pulse generator »5 is also sent via a · Ltituni

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20, which is amplified by an amplifier 15 in the same way as the start pulse and shaped by pulse formers 16 and 17. The mechanical security gate 19 has 6 connection points 21 to 26, of which either the connection points 22 and 23 and the connection points 24 and / or the connection points 21 and 22 and 25 and 26 can be connected to one another. In Pig. The position of the mechanical security gate 19 shown in FIG. 4, the connection points 22 and 23 and the connection points 24 and 25 are each connected to one another. The position of the mechanical main gate 19 shown corresponds to the position required for the measuring process. The start pulse is supplied from the line 18 via the connection point 24 and 25 and a line 27 to an electronic slope 28 gate. The electronic security gate consists either of a bistable multivibrator or of. an electronic safety toggle switch, a so-called ^w Pl.ipp-Flopp ^rt . The electronic security gate allows only a single one, namely the first start pulse via a line 29 to an electronic main gate 30. The electronic main gate 30 connects a line 31 to a line 32, which leads to a counter 33. Standard frequency signals from a crystal oscillator 34 to the; Counter 33 passed, but this is only possible as long as the main gate 30 allows. As soon as a stop pulse is passed from the pulse generator 5 via the line 20 and the mechanical security gate 19 or its connection points 23 and 22 and via a line 35 ^{to the} main gate 30, the connection of the lines 31 and 32 is interrupted. Di · standard frequency signals of the crystal oscillator 34 can not then go to the counter 33 so that this ibt ATE \ h # nbl ". ·. ;

109836/0298

The counter 33 consists of the In Flg. 4 shown Embodiment of four, as bistable multivibrators trained counting units 36 to 39, which with each other stay in contact. Each counting unit has 36 to 39 an ammeter 40 to 43, which is preferably ale Milliammeter is designed and has a mechanical zero point. The ammeters 40 to 43 can in microseconds, milliseconds, hundredths, tenths, whole Seconds etc. must be calibrated depending on the size of the speeds to be measured and the length of the measuring section.

The counting units 36 to 39 of the counter 33 are via a line 44 and preferably by hand actuating pressure switch 45 normally to ground 46 connected. When the pressure switch 45 is actuated, it flows a direct current from a direct current source 47 through the line 44 to the counter 33 and resets it to zero. In addition, a RUokstellimpulsgeber 48 designed as a monostable multivibrator is supplied with power, which via Lei-. lines 49, 50 and 51 reset pulses to electronic security gate 28 and electronic main gate 30; conducts, so that these are reset to readiness for measurement. I.

At the connection points 21 and 26 of the mechanical safety gate 19 is connected via lines 52 and 53, a likewise i if as a monostable multivibrator formed test [encoder 54, which may preferably be set by a pressure switch 55, by hand, in activity. The test pulse generator 54 sends test pulses of known period via the lines 52 and 53 to the mechanical security gate 19, whose connection points 21 and 26 are connected to the connection points 22 and 25, while the connection points 22 and 23 and 25 and 24 are no longer connected to one another as shown are. The test pulses can consequently on the one hand via the line 27 to the electronic

109836/0298 ".. ..Λ; · *

Security gate 28 and the first of them to electronic! Reach main gate 50 and open this temporarily. If this happens, the electronic main gate 20; already by the next Tcatlinpulc, the. U'uer the line 52 * the connection points 21 and 22 and the line 25 reaches the electronic main gate, closed again. Since the period of the test pulses is known, only a certain number of standard frequency signals can reach the counter y ^ from the crystal oscillator 34 via the lines 21 and 22 during this short period of time. This number of standard frequency signals is always the same, so that the counter y ^ must display the same number of standard frequency signals or the same time for each test process. If this is not the case - which, however, rarely occurs in practice - there is a fault and the device must then be examined.

To the second pulse shaper 17 for the im- ■; A second counter 56 is connected via a line 57 to the pulse generator 5 coming stop pulses. This counter is only used to count the total number of stop pulses generated, which enables the number of vehicles driving by to be counted. However, there is also the possibility of connecting the counter 56 via the line 57 to the pulse shaper 17: which converts the start pulses of the start pulse generator k .

The method described above and the measuring device required for this is exemplified by one Speed measurement for vehicles has been described. However, it is also possible to use this method for other speed or also to use pure time measurements and also the measuring device described above for such Use for other purposes.

109836/0298 'bathroom original

Claims (10)

1/21297 October 7, 1968 Χϊ / Di Franz Valentin Oebert, Lyttelton patent claims; 1. Measuring device for measuring speed, in particular of vehicles, on a measuring section of known length with one of a start pulse generator at the beginning of the measuring section set in action and stopped by a stop pulse generator at the end of the measuring section, whereby the start and stop pulse generator respond to wheel pressure, if necessary with pulse amplifier devices and electronic main gates, characterized in that the start and stop pulse generators (4 or 5) Jg from a pair of conductors (11, 13) with interposed piezoelectrically sensitive insulating layer (IJ) and possible amplifier devices (15) for Amplification of piezoelectric pulses are set up. 2. Measuring device according to claim 1, characterized in that the start and stop pulse generator (4 and 5) from each a shielded cable (11 to 14) are formed, the piezoelectrically sensitive, preferably from a polymer, e.g. polyvinyl chloride, existing insulating layer (IJ) between the central conductor (11) and the second conductor serving shield (12) is located. 3. Measuring device naoh claim 1 or 2, characterized in that that the start pulse generator with its circuit up to the main gate (30) on the one hand and the stop pulse generator with its circuit up to the main gate (20) on the other hand are designed as an identical pair. 4. Measuring device according to one or more of claims 1 to 2 »characterized in that between each pulse amplifier (15) and the electronic Sicherheitsbzw. Main gate (28 or 20) suppresses interference pulses. ? Start and stop pulse shaping to a Ecchteokwelle and to a predetermined voltage (of (^ Gug Unt rl6gen (art / g 1 from "2 No, 1 set of three changes v: 4. 9. t:. / ) 10983 6/0298 for example about 3 volts) more limiting than Schmitt-Auslb'sestromkreis trained pulse shaper (16) is arranged. 5. Measuring device according to claim 4, characterized in that that between each pulse shaper (16) and the electronic security or main gate (28 or 30) each start or stop pulse giving a constant, predetermined period of e.g. 100 milliseconds, is arranged as a monostable multivibrator, second pulse shaper (17). 6. Measuring device according to one or more of claims 1 to 5 * characterized in that between the start pulse generator (4) and the electronic main gate (30) also designed as a bistable multivibrator, only one single start pulse permitting electronic security gate (28) is provided for each measurement is and that both via the electronic security gate (28) and bypassing it as a monostable Multivibrator trained, preferably manually switchable, constant pulses of known Period-generating test pulse generator (54) to the electronic Main gate (30) is connected. 7. Measuring device according to one or more of the Claims 1 to 6, characterized in that on the start or stop pulse generators (4 or 5) a second Counter (56) connected to count the start or stop pulses is. 8. Measuring device according to one or more of claims 1 to 7, characterized in that the start or stop pulse generator (4 or 5) serving cables (11 to 14) of spacers (6) always at a fixed distance 1Ö9836 / 0298 are held, which is smaller than the center distance of the vehicles to be measured (3). 9. Measuring device according to one or more of the claims 1 to 8, characterized in that that it is arranged to keep pulses below a predetermined minimum voltage away from the main gate (30). 10. Measuring device according to claim 8, characterized «that the distance between the as Start or stop pulse generator (4 or 5) serving cables (11 to 14) is not significantly larger than 1.5 m. 109836/0298 Blank page