DE3302236A1 - Test apparatus for detecting the response time in compressed-air systems - Google Patents

Abstract

A test apparatus for detecting the time response of pressure changes, preferably in multi-circuit vehicle brake systems, comprises, for each brake circuit to be tested, a measuring element (4, 5; 4', 5'), each of which is connected electrically to a common timer (1) in such a way that a separate time display (t1, t2 = 11, 11') for each brake circuit and at least one common time-difference display (tDiff=11D) for all the time displays (t1, t2 = 11, 11') are arranged in the timer (1). Each measuring element (4, 5; 4', 5') is formed by a pressure-measuring device (4, 4') with a signal transmitter (5, 5') connected in series, each pressure-measuring device (4, 4') having an amplifier (41, 41'), an analog-to-digital convertor (42, 42') and an actual pressure display (Pactual, P'actual = 43, 43'), and each signal transmitter (5, 5') having a comparator (51, 51') and a desired pressure value input (Pdesired, P'desired = 52, 52'). Each comparator (51, 51') is electrically connected on the input side to the corresponding convertor (42, 42') and to the actual pressure display (Pactual, P'actual = 43, 43') and, on the output side, to the timer (1). The measuring elements (4, 5; 4', 5') of the test apparatus are connected to the test connections (73, 73') of the individual brake circuits via measuring lines (3, 3') provided with pressure sensors (2, 2'). Each brake circuit is furthermore connected to the timer (1) by start contact lines (8, 8') by means of the brake-pedal actuating device (71). <IMAGE>

Description

Test device to determine the response

time in compressed air systems.

Test device for determining the response time in compressed air systems The present invention relates to a test device for determining the response time of pressure changes in compressed air systems, especially in multi-circuit brake systems on motor vehicles according to the preamble of claim 1 when testing the brake pressure build-up or the reduction in brake pressure, especially in the case of trucks and trucks Usually, the response time of the vehicle that is not braked independently, for example of the trailer, from the time the brakes are applied on the coupled towing vehicle to to activate the brake system to be tested or, in the case of a vehicle, with actuated Braking from the time the brakes are released until the pressure is reduced in the corresponding Brake using a stopwatch based on acoustic and visual perceptions to undertake.

However, this results in measurement errors that affect the ability to react of the examining persons.

It is also known for such time measurements with pressure test devices Use equipped measuring devices, with the time of the pressure rise automatically from zero to a predetermined pressure value or the pressure drop from that value is measured to zero.

Such measurements for functional testing can be used for both the towing vehicle carried out alone, as well as for the entire truck combination, even with several trailers will. Due to the length of the measuring lines and external influences, for example the values obtained can be falsified by temperature differences.

According to DE patent specification 21 38 975, a measuring arrangement is for determining the change in pressure over time has been proposed, at which a in the braking force system Connectable electrical pressure voltage converter with a downstream signal transmitter is provided, with a first step below the maximum Brake pressure, automatically calibrated pressure value entered into a memory and the actual measurement is only carried out in a second step.

Each measuring point to be tested can only be measured individually, what is particularly time-consuming in multi-circuit brake systems, with the following necessary manual recording and evaluation of the measured values made errors can. Timing of the braking behavior of the individual axes to one another is only possible in comparison and cannot depend on the braking response can be read from each other.

The object of the invention is to provide the measurements for all Carry out evaluation of the required measuring circuits at the same time and display them in this way, that good or incorrect time values depending on the same test process the pressure changes are displayed in the timing device without additional evaluation will.

The invention is defined by the characterizing part of claim 1 solved.

The test device according to the invention provides an overall evaluation of the Measurements of all existing measuring circuits, for example brake circuits, in one time running together Examination guaranteed. The changes in pressure over time can be displayed digitally in both absolute and differential pressure values. For a quick check of the functionality of the vehicle braking system can advantageously only evaluate the final differences in time Pressure changes are displayed. If, for example, due to the Checking a brake setting that needs to be corrected can be carried out immediately then an overall test of the entire braking system in one work process without additional ones AuswertLng are repeated, whereby such defects very quickly and 2 ureliably can be fixed.

Another advantage is the universal application of the test device, at which both the temporal pressure behavior of vehicle braking systems of all Type can be checked, but also individual compressed air elements, such as Compressed air valves, as well as the functionality of compressed air lines on one can be checked easily.

The invention is to be described in more detail below using an exemplary embodiment explained.

For the sake of clarity, only one of those in the For example, two measuring elements shown in the drawing are described, with these The same description applies to the second measuring element.

In the drawing, a multi-circuit brake system to be tested is one Truck with trailer shown, with a brake pedal with 71, a brake cylinder with 74.74 'with corresponding test connections 73.73' and connecting lines 72.72 ' are designated, and between test connections 73,73 'and a pressure measuring device each 4 intermediate pressure transducers 2.2 'with measuring lines 3.3' are connected. A measuring element 4, 5; 4 ', 5' is provided for each brake circuit to be measured, whereby, For example, as shown in the drawing, the test device has at least two measuring elements 4,5; 4 ', 5'.

The individual measuring elements 4, 5; 4 ', 5' share a common timing device 1 electrically connected so that for each brake circuit in the timing device 1 a separate time display tl, t2 = ll, ll 'and for all time displays tl, t2 = ll, ll' at least one common time difference display t Diff = 11D are arranged. Each Measuring element 4, 5; 4 ', 5' is made up of a pressure measuring device 4, 4 'and a downstream one Signal transmitter 5.5 'formed, the pressure measuring device 4.4' from an amplifier 41, 41 ', a converter 42, 42', preferably an analog / digital converter with a BCD code (BCD = binary coded decimal digit), as well as an ACTUAL pressure value display PIST, P'IST = 43.43 ' and the signal generator 5, 5 'from a comparator 51, 51' and a nominal pressure value input P50LL, P'50L = 52.52 'exist. Each comparator 51.51' is on the one hand on the input side with the corresponding converter 42.42 'and the ACTUAL pressure indicator PI5T, P'IST = 43.43' and on the other hand with the corresponding SET pressure input PSoLLP's0L = 5252 '= 52.52' connected and electrically connected on the output side to the timing device 1 ACTUAL pressure display PI5T, P IsT = 43.43 'is between the converter 42.42' and the comparator 51,51 'interposed. The input side of each pressure transducer 2, 2 'is across Test connections 73.73 'with the brake system that can be actuated by brake cylinder 74.74' and with its output side, as already mentioned, with the amplifier 41, 41 ' Pressure measuring device 4,4 'connected.

The time measuring device 1 has time displays tlt2StDiff = 11 ll ', llD on which both the temporal absolute values and the temporal difference values of the two brake circuits to be compared digitally. The provision the displayed time values t1, t2, tDiff = 11,11 ', 11D can be manually reset 12 take place. The time measuring device 1 has one for each measuring element 4, 5; 4 ', 5' Response control display 13.13 'on. The timing device is for each brake circuit 1 additionally connected to the brake pedal 7] by starting contact lines 8, 8 '. For quick functional checks of multi-circuit braking systems, in which the temporal Absolute values of each brake circuit do not have to be checked, but where the correct one Timed brake response sequence of the individual brake circuits must be guaranteed must, it is beneficial merely the time difference values determine, in this case between the timing device 1 and the brake pedal 71 for each brake circuit provided starting contact lines 8,8 ' can stay switched off. The test device is preferably connected to a 220V power supply connected. (not shown) The mode of operation of the test device according to the invention emerges from the following.

It is a test of the entire time behavior of a multi-circuit braking system a truck with a trailer, for example for two brake circuits, where the absolute as well as the difference time values of the response times of the to be compared Brake circuits can be measured via corresponding measuring elements 4, 5; 4 ', 5'. In the first The brake cylinders 74 of the rear axle of the tractor unit are, for example, measuring element 4, 5 and the brake cylinders 74 'of the trailer rear axle are checked in the second measuring element 4', 5 '. By actuating the brake pedal 71, the brake cylinders 74, 74 'are at a maximum applied, the brake pressure also being applied to the test connections 73,73 'connected Pressure transducer 2.2 'acts.

At the same time, the start contact lines are used for each brake circuit to be tested 8.8 'the timing device 1 is started and in the relevant time display tl, t2 = ll, ll' displayed.

The pressure transducers 2,2 'convert the max.braking pressures into electrical ones Voltage, preferably into a DC voltage, which is generated in the amplifier 41, 41 'of the pressure measuring device 4,4 'is amplified to a suitable value. There are two commercially available pressure transducers 2.2 'is sufficient, one for pressures up to about 10 bar and one for pressures over 10 bar.

The electrical voltage j amplified in the amplifier 41; 41 'becomes in the downstream converter 42, -42 'by means of one of the BCD codes (BCD = binary coded Decimal digit) converted to analog digital and in the pressure display PI5T. = 43.43 ' displayed and continuously forwarded to the comparator 51,51 'of the signal generator 5,5'. The corresponding SET pressure value, which is below the maximum pressure of the to be measured Brake cylinder 74.74 'is located before the start of the test in the nominal pressure value input PSOLL, TARGET = 52.52, set. The comparator 51 compares the entered cyclically by the pressure measuring device 4,4 'at equal time intervals ACTUAL pressure value with the stored target pressure value of the target pressure value input PSoLL, P'50LL = 52.52 ' and as soon as these are the same, a stop signal is sent to the time measuring device 1 and in the time display tl, t2 = of the corresponding measuring element 4,5; 4'5 ' the response time stopped. At the same time a response control indicator 13,13 'lights up of the corresponding measuring element 4, 5; 4 ', 5'. For example, the time display t2 = ll 'of the second measuring circuit 4', 5 '(brake circuit of the trailer rear axle) stopped, the response control indicator 13 'lights up at the same time and also starts at the same time the time difference display tDiff = llD, which runs until a stop signal of the signal generator 5 of the first measuring element 4, 5 (brake circuit of the rear axle of the towing vehicle) delivered to the time measuring device 1 and the time display tl = ll and the time difference display tDiff = llD must be stopped.

So in this example - as prescribed - it comes first to brake the trailer and later the towing vehicle. If the absolute tl, t2 = ll, ll ' and the differential response times are within the tolerance range, this test can be carried out as to be completed well rated.

In the case of short vehicle checks, which are only a review and, if necessary, to readjust the chronological order of responses braking in a multi-circuit braking system, i.e. first the Activation of the brake cylinder of the trailer rear axle and then activation the brake cylinder rear axle of the tractor unit can be carried out in an advantageous manner a simplified, very clear and easy to read, in one test procedure Any difference time measurement that takes place must be carried out as follows: The start contact lines 8.8 'between the brake pedal 71 and the timing device 1 remain switched off, so that by actuating the brake pedal in the timing device 1 for the to be measured Brake circuits the time displays t1, t2 = ll, lI 'are not started and only, let already described, about the pressure transducers 2.2 ', the pressure measuring devices 4.4' and the signal transmitter 5,5 'measured the pressure changes over time, compared and signals to the timing device 1 are given. It is believed, that for example again for the second measuring element 4''5 '(brake circuit of the trailer rear axle) the ACTUAL pressure value first reaches the SET pressure value and the comparator 51 'starts the timing device 1 does not emit a stop signal but a start signal and the Difference time display tDiff = llD starts, with the corresponding response control display 13 'lights up. As soon as the pulse of the signal generator 5 of the first measuring element 4,5 (Brake circuit of the rear axle of the towing vehicle) is sent to the timing device 1, this stops the difference time display tDiff = llD. Through this single difference time value the functionality of the braking force to be checked is checked.

The test device could be equipped for a large number of brake circuits to be tested so that it would be possible to simultaneously put all the brake circuits to be tested in to control an examination process and in absolute and / or difference time values to display.

The test device can be controlled in a known manner with a microprocessor and the test results via a suitable output device in data and, for example be recorded in graphical representations.

The design options are based on those shown in the drawing Examples are not limited. The delay times on hydraulic and pneumatic components, for example on valves, as well as delay times the pressure build-up in pipelines can be measured.

List of the reference symbols used 1 time measuring device tl = 11 Time display of the first measuring element t2 - 11 'Time display of the second measuring element t = llD difference time display 12 resetting of the time displays 13, 13 'response control displays 2, 2 'pressure transducers 3, 3' measuring lines 4, 5; 4 ', 5' measuring elements 4, 4 'pressure measuring devices 41.41 'amplifier 42.42' converter (analog to digital converter) with BCD codes (BCD = Binary coded decimal digit) IST 43 IST pressure display of the first measuring element RIST = 43 'ACTUAL pressure display of the second measuring element 5, 5' Signal transmitter 51, 51 'Comparator TARGET = 52 TARGET pressure value input of the first measuring element P'SOLL = 52, TARGET pressure value input of the second measuring element 6 ON / OFF switch, preferably -'an-- a 220V power supply connected

7 Connection part of the multi-circuit compressed air brake system 71 actuating device, e.g. brake pedal 72.72 'connecting lines 73.73' test connections 74.74 ' Brake cylinder 8, 8 'start contact lines

Claims (3)

Claims W) Tester for determining the response time of Changes in pressure in compressed air systems, especially in multi-circuit brake systems Motor vehicles, essentially consisting of a pressure transducer (2, 2 ') of a time measuring device (1), a pressure measuring device, a signal transmitter and connections to the to be measured Brake system, characterized in that a measuring element (4,5; 4 ', 5') is provided, and that the individual measuring elements (4,5; 4 ', 5') with a Timing device (1) are electrically connected so that for each brake circuit in the time measuring device (1) a separate time display (tl, t2 = 1 ') and for all Time displays (tl, t2 = ll, ll ') at least one common time difference display (tDiff = llD) are arranged. 2. Test device according to claim 1, characterized in that each measuring element (4,5; 4 ', 5') from the pressure measuring device (4,4 ') with the downstream signal transmitter (5,5 ') is formed, and each pressure measuring device (4,4') an amplifier (41,41 '), a converter (42,42 ') and an ACTUAL pressure value display (PIST, P'IsT = 43S43') and each signal transmitter (5,5 ') a comparator (51,51') and a nominal pressure value input (Pset, P'50LL = 52.52 '), with each comparator (51.51') on the input side on the one hand with the corresponding converter (42,42 ') and the ACTUAL pressure display (PIST, P'IsT = 43,43') and on the other hand connected to the corresponding SET pressure input (PSoLL, P'SoLL = 52.52 ') and is electrically connected on the output side to the timing device (1). 3. Test device according to claim 2, characterized in that the time measuring device (1) a response control indicator (13, 13 ') is provided for each measuring element (4, 5; 4'5') is.