GB2096327A

GB2096327A - Testing tachographs

Info

Publication number: GB2096327A
Application number: GB8210009A
Authority: GB
Original assignee: BETRIEB DES KOM VEB EAW BERLIN; WEINERT E MESSGERAETEWERK
Current assignee: BETRIEB DES KOM VEB EAW BERLIN; WEINERT E MESSGERAETEWERK
Priority date: 1981-04-06
Filing date: 1982-04-05
Publication date: 1982-10-13
Also published as: RO83193B; RO83193A; CS263454B1; DE3211353A1; FR2505066A1; DD160241A3; HU185704B

Abstract

All the functions of a tachograph (1), including the pulse leads (3) between the tachograph (1) and sensors, (6, 7) can be tested by means of a portable device (10) which simulates the main functions oft e tachograph. The main functions comprising the velocity and engine speed readings are tested statically and dynamically by inputting corresponding pulse trains, and the reading of the distance travelled is checked by pulse counting. The pulse trains fed in are simultaneously recorded on a test chart. The pulse leads (3) are tested for continuity and short circuit by applying a test voltage. For the purpose of performing the test, the portable device (10) is connected into the pulse leads (3) between the tachograph (1) and sensors (6, 7) by means of plug connectors and adaptors (8, 9, 11-16). <IMAGE>

Description

SPECIFICATION A method of, and a device for, testing tachographs The invention relates to a method of, and the device for, testing tachographs, particularly tachographs which operate with electronic processing of measured vehicle parameters.

Known means for the testing of mechanical tachographs include, inter alia, tachogenerators.

However, these cannot be used for testing electronic tachographs. Roller-type test stands for motor vehicles are known. These, however, cannot be used to test all the functions of a tachograph and in any even involve a very timeconsuming and energy-consuming technique.

Test stands for the maintanence of tachographs which have been removed from the vehicles are also known. These kinds of test stands also involve a labour-intensive method and are only suitable for testing tachographs which have been removed from the vehicles. It is also possible to drive along a test track and to compare the functions of a tachograph with predetermined desired values. However, not all the functions of the tachograph can be tested and such a test also involves considerable expense such as the consumption of fuel and the provision of a special test track.

An object of the present invention is to provide a method of testing tachographs and a device for performing this method, which method and device can be provided at low expense and enable rapid and logical testing of all functions of a tachograph.

In accordance with the invention, this object is achieved in that all major functions of a tachograph are tested in a complex manner, including the pulse leads between the tachographs and sensors, by means of a portable device which, inter alia, simulates the main functions of the tachograph. The complex testing of the main functions of the tachograph, such as readings of the velocity and engine speed and distance travelled, is performed in the following manner. The readings of velocity and engine speed are tested statically by inputting constant pulse trains and also dynamically by inputting a variable pulse train. The reading of the distance travelled is tested by counting pulses fed into the tachograph.The pulse trains which are fed in are at the same time recorded on a test chart from which the constants for the velocity and/or the engine speed, the recording of the distance travel, and the dynamic values of velocity and engine speed can be read as a delta function after the test has been completed.

The variable pulse train for the dynamic testing of the function of the velocity and engine speed readings passes through a range of values from zero to the maximum value and back to zero value of the velocity and engine speed readings within the corresponding cycling time of the test step.

The velocity and engine speed readings of the tachograph are jointly tested during the course of the dynamic testing of the function of the velocity and engine speed readings.

The pulse leads between the tachograph and the sensors are tested for continuity and shortcircuit by applying a test voltage to them, faults at the same time being indicated.

In order to perform the test, the device is connected into the pulse leads between the tachograph and the sensors by removing the pulse leads from the tachograph and connecting the tachograph and the pulse leads to the device by way of adaptors, and by removing the pulse leads from the sensors and terminating them by further adaptors. Thus, all the functions of a tachograph can be tested in a complex manner with the tachograph in its fitted state and the vehicle stationary, and also when the tachograph has been removed from the vehicle.

In a device, in accordance with the invention, for realising the method, a functional group is used for each main function of the tachograph to be simulated. The functional groups are connected, independently of one another, to a control unit which also includes operating and indicating devices. The functional groups disposed in the device for the purpose of simulating the main functions include a quartzcontrolled frequency transducer having a programmable frequency divider for producing a plurality of different velocity and engine speed values, a voltage-controlled frequency generator for producing variable values of the velocity and engine speed, and a pulse generator and counter with automatic cut-out for checking the distance travelled.A plurality of window discriminators is provided in the device for the purpose of testing the pulse leads between the tachograph and the sensors for continuity and short-circuit.

A power supply unit can be used which is fed by the voltage of the vehicle electrical system but whose output voltage is independent of the value of the applied voltage of the vehicle electrical system.

All the functional groups, the control unit and the power supply unit are accommodated in a portable case.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a diagram showing the complete assembly of a tachograph with sensors; Fig. 2 is a diagram showing the arrangement of a device for performing the method in accordance with the invention; and Fig. 3 is a block circuit diagram of a device in accordance with the invention.

Referring to Fig. 1, a tachograph (1) is connected to pulse leads (3) by way of a plug connecter (2), and the pulse leads are connected to sensors (6, 7) by way of further plug connectors (4, 5). As is shown in Fig. 2, the device (10) is first connected into the assembly comprising the tachograph (1), pulse leads (3) and sensors (6, 7) for the purpose of testing the tachograph (1) including the pulse leads (3). For this purpose, the pulse leads (3) are removed from the tachograph (1), that is to say, the plug connector (2) is disconnected, and the left hand and right hand halves (8, 9) of the plug connector (2) are each connected to the device (10).The plug connector (4) comprising left hand and right hand halves (11, 12), and the plug connector (5) comprising left hand and right hand halves (13, 14) are also separated, that is to say, the pulse leads (3) are separate from the sensors (6, 7) and the left hand halves (1 1, 13) of the plug connectors (4, 5) are connected to adaptors (15, 1 6) which incorporate resistance combinations.

Thus, the pulse leads (3) are terminated by the adaptors (15, 16). The device (10), shown as a block circuit diagram in Fig. 3, is of portable construction and includes a control unit (17) which at the same time incorporates operating and indicating devices, a power supply unit, and a functional group for each main function to be simulated. The functional groups, disposed independently of one another in the device (10), comprises a quartzcontrolled frequency transducer (20) having a programmable frequency divider, a voltagecontrolled frequency generator (21) and a pulse generator and counter (23) having automatic cutout.

The main functions of the tachograph (1) which are tested are the velocity and engine speed readings and the reading of the distance travelled, the velocity and engine speed readings being tested both statically and dynamically.

The function of the velocity and engine speed readings is tested statically by feeding the tachograph (1) with at least two constant pulse trains which are produced by the quartzcontrolled frequency transducer (20).

The function of the velocity and engine speed readings are tested dynamically by feeding the tachograph (1) with a variable pulse train produced by the voltage-controlled frequency generator (21). The velocity and engine speed readings are tested simultaneously during both the static and the dynamic function test. The constant pulse trains fed to the tachograph (1) during the static function test correspond to constant values of the velocity and engine speed.

The variable pulse train fed to the tachograph (1) during the dynamic function test corresponds to the generation of a changing value for the velocity and engine speed. During the dynamic function test the variable pulse train passes through a range from zero value to maximum value and back to zero value of the velocity and engine speed readings, the extreme values of the velocity and engine speed readings of the tachograph (1) being simultaneously tested.

The reading of the distance travelled is tested by counting pulses which are fed into the tachograph (1) and which are produced and counted by the pulse generator and counter (23).

Furthermore, the device (10) includes a plurality of window discriminators (22) for testing the pulse leads (3) between the tachograph (1) and the sensors (6, 7) for continuity and shortcircuits, faults at the same time being indicated.

In order to perform this test step, a test voltage is applied to the pulse leads (3) by the device (10).

The cycling time and sequence of the test steps are determined in an optional manner by the control unit (17), a function reading being effected at each test step. The output gates (18, 19) of the control unit (17) constitute the connection to the tachograph (1) and to the pulse leads (3) respectively.

The lighting and the auxiliary power supply of the tachograph (1) are tested by simple optical indication when the device (10) is connected in accordance with Fig. 2.

Recording is tested by means of a test chart which has been placed into the tachograph (1) before commencement of the test. After the test has been completed, the constant values for velocity and/or engine speed, the recording of the distance travelled and the operating time group mark, with the operating time group switch in its appropriate position, and the dynamic values of velocity and engine speed can be read from the chart as a delta function.

Advantageously, the voltage of the vehicle electrical system is used to supply the device (10) with power.

The output voltage made available by the power supply unit is independent of the value of the applied voltage of the vehicle electrical system.

Claims

1. A method of testing the technical operating characteristics and function of a tachograph, particularly a tachograph which operate with electronic processing of measured vehicle parameters, wherein all functions of the tachograph, including the operational condition of pulse leads between the tachograph and associated sensors, are tested by means of a device which, inter alia, simulates the main functions of the tachograph.

2. A method as claimed in claim 1, wherein a static functional test of velocity and engine speed values is simultaneously effected by feeding constant pulse trains to the tachograph, a dynamic functional test of velocity and engine speed readings is simultaneously effected by feeding a variable pulse train to the tachograph, and a function test of the reading of the distance travelled is effected by counting pulses fed to the tachograph, the pulse trains fed in for the functional test at any given time simultaneously being recorded on a test chart, and wherein the pulse leads between the tachograph and the sensors are tested for continuity and short-circuit by applying a test voltage to the pulse leads, faults being simultaneously indicated.

3. A method as claimed in claim 2, wherein the variable pulse train for the dynamic functional test of velocity and engine speed readings passes through a range from zero value to maximum value and back to the zero value of the velocity and engine speed readings within a predetermined cycling time for the test step, the velocity and engine speed readings of the tachograph simultaneously being tested.

4. A method as claimed in claim 1 or 2, wherein the device which, inter alia, simulates the main functions in an optional sequence and cycling time, is connected into the pulse leads between the tachograph and sensors by removing the pulse leads from the tachograph and connecting the tachograph and the pulse leads to the device by way of adaptors, and by removing the pulse leads from the sensors and terminating them by means of further adaptors.

5. A method as claimed in claim 1 or 2, wherein all the functions of the tachograph are tested with the tachograph in its fitted state and the vehicle stationary.

6. A device for testing the technical operating characteristics and functions of tachographs, particularly tachographs which operate with electronic processing of measured vehicle parameters wherein a respective functional unit in the device is used to simulate each main function of the tachograph, each functional unit being connected to a control unit which includes operating and indicating devices, all the functional units, and the control unit being accommodated in a portable case.

7. A device as claimed in claim 6, wherein the device includes a quartz-controlled frequency transducer having a programmable frequency divider for producing a plurality of different velocity and engine speed values, a voltagecontrolled frequency generator for producing changing values of the velocity and engine speed, a plurality of window discriminators for testing the pulse leads being the tachograph and sensors for continuity and short-circuit, and a pulse generator and counter, having automatic cut-out, for checking the distance travelled, all of the latter elements being arranged to be operable independently of one another.

8. A device as claimed in claim 6, wherein a power supply unit which is fed with the voltage of the vehicle electrical system but whose output voltage is independent of the value of the applied voltage of the vehicle electrical system.

9. A device for testing tachographs, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

10. A method of testing tachographs substantially as hereinbefore described with reference to the accompanying drawings.