GB2592181A

GB2592181A - Rig for testing ultrasonic height and pressure sensors under changing environmental conditions and method of using said test rig

Info

Publication number: GB2592181A
Application number: GB1917020.8A
Authority: GB
Inventors: Draghici Vasile; Alexandru Moisa Victor
Original assignee: Continental Automotive GmbH; Continental Automotive Romania SRL
Current assignee: Continental Automotive GmbH; Continental Automotive Romania SRL
Priority date: 2019-11-22
Filing date: 2019-11-22
Publication date: 2021-08-25
Anticipated expiration: 2039-11-22
Also published as: GB201917020D0; GB2592181B

Abstract

A test rig, for testing ultrasonic height and pressure sensors 2 under predetermined variation of air pressure, humidity and temperature, comprising: a base plate 9; a support 14 for receiving an airtight chamber 3, comprising a reflector 5 and a bead plate 1; a top plate 11; a plurality of guiding elements 12; a mobile plate 10 adapted to slide along the guiding elements; an air supply connector 6 generating variation of air pressure inside airtight chamber for moving the mobile plate; a plurality of contra pressure elements 13 for providing a counterforce to the mobile plate for the force exerted by the airtight chamber to the mobile plate while it is inflated; at least four ultrasonic height pressure sensors 2; a reference height sensor 7; and a reference pressure sensor 8. A processing unit is adapted to receive the reference pressure and height measurements, and the testing measurements, to compare them and determine if the testing measurements of each of ultrasonic height pressure sensors are within predetermined tolerances. A message is sent to a display if the testing measurements are within the predetermined tolerances. The temperature may vary from -40 to 85 degrees Celcius, and/or the humidity is up to 96%. The rig may further comprise means for tilting the plane of the reflector, and a gyroscope (23, fig.10) for measuring the tilt of the movable plate.

Description

Rig for testing ultrasonic height and pressure sensors under changing environmental conditions and method of using said test 5 rig

Field of the invention

The invention is related to the field of testing devices that use ultrasonic measurements at atmospheric pressure and above it in environmental conditions used in the automotive industry, to the field of testing, validation, and calibration devices to different air cavities.

In particular, the invention refers to a test rig for testing ultrasonic height pressure sensors under changing environmental 15 conditions, and method of using said test rig.

Background of the invention

It is known that, ultrasonic sensors are usually used in distance measurement scenarios like parking assistance, liquid 20 level measurement being operated at atmospheric pressure. Ultrasonic height pressure sensors (UHPS) are ultrasonic sensors that are meant to measure height in a vehicle air bellow, commonly used as a suspension element, which is usually pressurized at above atmospheric pressure and operated in 25 changing environmental conditions.

In order to be used in automotive industry, the ultrasonic height pressure sensors need to be tested, calibrated and validated, which may be done for instance by a test rig or a test system designed for testing the air bellows specifically adapted to be used for this purpose.

However, in order to be used for testing the ultrasonic height pressure sensors a test rig needs to meet certain requirements.

Thus, since the ultrasonic measurement process consists in emitting a sound wave by an ultrasonic element and listening for the returned echo bounced by a reflector, the test rig needs a cavity that allows the ultrasonic height pressure sensors and their equipment to be mounted to it and to give a flawless space for the ultrasonic waves to propagate to the reflector and vice versa.

The height between the ultrasonic element and the reflector needs to be variable and controlled with a moderate precision by introducing or venting air into the test air cavity that means the test air cavity needs to be airtight.

Additionally, the test rig needs enough space to mount all additional equipment for operating the ultrasonic height pressure sensors that leads to a test rig having a required weight, and minimum required dimensions.

Moreover, since the ultrasonic height pressure sensors are regularly used to measure height in a vehicle air bellows that are operated in changing environmental conditions, where temperature varies from -40°C up to +85°C, the humidity is up to 96%, and the pressure within air bellows rises to at least 8 bars, and the airtight of the air bellows have to be maintained in said conditions, the testing of the ultrasonic height pressure sensors has to be realized in the environmental conditions, which are usually simulated in climate test chambers.

Even there are known many test rigs for testing the ultrasonic height pressure sensors, these do not comply with the 25 requirements for testing the ultrasonic sensors in the above-mentioned conditions.

One of the disadvantages of the test rigs from the prior art is that the current test rigs used for testing the ultrasonic height pressure sensors are outsized to a regular climate test chamber, that means they cannot be operated in a controlled environment of withstanding pressure, temperature and humidity changes requirements for testing the ultrasonic height pressure sensors in changing environmental conditions.

Yet another disadvantage of the prior art is that the current rigs used for testing the ultrasonic height pressure sensors do not permit the testing the multiple the ultrasonic height pressure sensors, and do not permit their adaptation to different mechanical dimensions of the sensors.

Problem solved by the invention The problem solved by the invention is to provide a test rig for testing ultrasonic height pressure sensors and a method of using the test rig, which provide accurate measurements, and verifications of the ultrasonic height pressure sensors to calibrate andvalidatethemtobeused in the automotive industry complying with the requirements of the high pressure of the air cavities wherein the ultrasonic height pressure sensors are mounted, and changing environmental conditions, whereas also provide the possibility for testing in the same time multiple ultrasonic height pressure sensors of various sizes.

Summary of the invention

In a first aspect of the invention the inventors conceived a test rig for testing ultrasonic height pressure sensors under predetermined variation of air pressure, humidity and temperature, said test rig comprising a support fixed to center of a base plate for receiving an airtight chamber which comprises a reflector mounted at the bottom part, and a bead plate on the top of the airtight chamber, it being mounted with the reflector attached to said support so that the longitudinal axis of the said chamber is perpendicular to said base plate plane. A top plate is arranged parallel to said base plate, and a plurality of guiding elements, at least 3, are fixed between the base plate and said top plate, symmetrically placed in respect to the longitudinal axis of the airtight chamber. A motile plate is supported by said airtight chamber, which vertically slides along the guiding elements within the distance between the bead plate and top plate. An air supply connector is mounted on said bead plate being configured to generate a pressure above atmospheric pressure inside airtight chamber for moving the mobile plate by the force exerted by inflated airtight chamber and to control said pressure. A plurality of contra pressure elements is placed symmetrically in respect to the longitudinal axis of the airtight chamber or at least one contra pressure element is placed along longitudinal axis of the airtight chamber for providing a counterforce to the mobile plate for the force exerted by the airtight chamber to the mobile plate while it is inflated, a pressure above atmospheric pressure inside the airtight chamber being created. At least 4 ultrasonic height pressure sensors to be tested are mounted on said bead plate and are pneumatically connected to the airtight chamber, being configured to measure the height between the bead plate and reflector during the inflating the airtight chamber, and to send the testing measurements to a processing unit. Two reference sensors, a reference height sensor mounted on said mobile plate, being configured to measure the height between the base plate and the mobile plate during the inflating of the airtight chamber, and to send said height measurements to said processing unit, and a reference pressure sensor mounted on said bead plate, pneumatically connected to the air chamber, being configured to measure the pressure inside air chamber, during the inflating the airtight chamber, and to send the reference pressure measurements to said processing unit.

The processing unit is arranged: * to receive the reference pressure measurements from said reference pressure sensor, and to calculate the related predetermined reference tolerance pressure interval based on 30 prescribed error value; * to receive said height measurement from said reference height sensor, and to calculate de reference height measurement from bead plate to the reflector by taking into consideration the height of the support and to calculate the related predetermined reference tolerance height interval based on prescribed error value; * to receive the testing measurements from each of said 5 ultrasonic height pressure sensors, and to compare them with said reference pressure and height measurements based on prescribed error value; * to determine if the testing measurements of each of said ultrasonic height pressure sensors are comprised in said 10 predetermined reference tolerances intervals in respect to said reference pressure and height measurements; An at least anon-volatile memory is configured to temporary store at least: * the results of the reference pressure and height measurements, 15 reference tolerance pressure and height intervals based on prescribed error value and of the testing measurements; * the results of comparisons between of the reference measurements, and of the testing measurements; * the validated measurements for each of the testing 20 measurements; Test rig further comprises a network configured to assure communication between said processing unit, non-volatile memory, and said reference pressure sensor, and reference height sensor, said test rig being configured such that a message for each of the ultrasonic height pressure sensors is sent to a display by said processing unit if the testing measurements of respective ultrasonic height pressure sensor are comprised in references predetermined tolerances intervals in respect to said reference pressure and height measurements.

In a second aspect of the invention it is provided a method of using the test rig for testing the ultrasonic height pressure sensors under predetermined variation of air pressure, humidity and temperature, wherein following steps are carried out: -mounting said test rig in a climate chamber wherein predetermined variations of temperature and humidity are maintained; -mounting the ultrasonic height pressure sensors to be tested within the corresponding connecting holes within the air chamber; -supplying the air bellow with the air at a predetermined pressure by means of said air supply connector; -measuring the pressure within the airtight chamber by said reference pressure sensor, and calculating the related reference tolerance pressure interval based on prescribed error value by said processing unit and sending the reference pressure measurements and said reference tolerance interval to said non-volatile memory; -measuring the pressure within the airtight chamber by the ultrasonic height pressure sensors and sending the testing measurements to said non-volatile memory; -measuring the height between the base plate and mobile plate by reference height sensor, and sending said height measurements to said processing unit; -determining the reference height measurements between the reflector plane and the bead plate by taking into consideration the height of said support, and determining the related tolerance height interval based on prescribed error value by means of said processing unit and sending the reference height measurements and reference height tolerances interval to the at least one non-volatile memory; -measuring the height between the reflector plane and the bead plate by means of ultrasonic height pressure sensors, and sending testing height measurements to the at least one non-volatile memory; -comparing by means of said processing unit: * of the referenced height measurement between the reflector plane and said bead plate determined by said processing unit and testing height measurement between the reflector plane and the bead plate as measured by ultrasonic height pressure sensors; * of the reference pressure measurements within the airtight chamber as measured by the reference pressure sensor and the testing pressure measurement as measured by ultrasonic height pressure sensors; -determining by means of said processing unit if the following conditions are fulfilled: * if the measured height between the reflector plane and the bead plate is situated within the reference tolerance height interval based on prescribed error value; * if the measured pressure within said air bellow measured by the ultrasonic height pressure sensors is situated within the reference pressure tolerance interval; -in the affirmative case, validating the ultrasonic height pressure sensors by means of said processing unit and displaying the information on its display.

Advantages of the invention The main advantages of this invention are the following: i) Using the test rig and the corresponding method in a climate chamber. The proposed solution meets the weight and dimension limits imposed by the internal volume of generally available climate test chambers usually used for validating automotive components. The invention provides the possibility to use the test rig inside the climate test chamber, where relative pressure within the air bellow rises up to 8 bars in the whole range of environmental conditions used in the automotive industry, from -40°C up to +83°C and the change in humidity up to 96%.

ii) Testing multiple ultrasonic height pressure sensors. A big advantage is that this test rig allows the testing of multiple ultrasonic height pressure sensors samples in the same time that greatly reduces the costs and time associated.

iii) Adaptability for multiple dimensions of the ultrasonic height pressure sensors Even that some parts of the chassis of the test rig might require some machining, the entire test rig may be easily adapted to fit different air cavities and ultrasonic height pressure 10 sensors samples with different mechanical dimensions.

iv) Low cost and ease of purchasing of the components.

Brief description of the drawings

Fig. 1 depicts a test rig according to the invention for testing 4 ultrasonic height pressure sensors samples; Fig. 2 depicts the air bellow with its special adaptations to be used in the test rig according to the invention; Fig. 3 depicts the chassis for the test rig according to the invention; Fig. 4 depicts a dual test rig, representing an embodiment of the test rig according to the invention wherein two air spring bellows are mounted one above the other axially; Fig. 5 depicts the chassis of the embodiment presented in the Figure 4; Fig. 6 depicts an embodiment of the test rig where the bead plate maybe moved horizontally in respect to the reflector plane by means of four auxiliary air bellows; Fig. 7 depicts the equidistant positioning of the auxiliary air bellows 19 in respect to each other around the center of the bead plate; Fig. 8 depicts the air bellow and guiding supports of the air bellow movement within the test rig chassis; Fig. 9 depicts the bead plate movement in relation to the reflector plane by inflating two of the auxiliary air bellows at a higher pressure than other two auxiliary air bellows placed on the same axis; Fig. 10 depicts an embodiment of the invention using a movable plate by 4 auxiliary air bellows placed under it; Fig. 11 depicts the air bellow and the assembly of the base plate and movable plate of the embodiment shown in the Fig. 10; Fig. 12 depicts the bead plate movement in relation to the reflector plane in the embodiment shown in the Fig. 10; Fig. 13 depicts the assembly of the auxiliary air bellows 19 mounted on the base plate.

List of references in the drawings: 1. bead plate 2. ultrasonic height pressure sensors 3. airtight chamber 3.1. secondary airtight chamber 4. piston 5. reflector 6. air supply connector 7. reference height sensor 8. reference pressure sensor 9. base plate 10. mobile plate 11. top plate 12. guiding elements 13. springs 14. support 15. bushings 16. guiding supports 17. bumper 18. additionally, plate 19. auxiliary air bellows 20. dual mobile plate assembly 20.1. uppermobileplateof the dualmobileplate assembly 20.2. lowermobileplateof the dualmobileplate assembly 20.3. spacer 21. position sensor 22. mechanical stopper 23. gyroscope 24. ultrasonic wave 25. additional air supply connector 26. bushing plates

Detailed description

The inventors created a test rig for testing ultrasonic height pressure sensors under predetermined variation of air pressure in the air cavity pneumatically connected with the sensors, and of the humidity and temperature of the medium where the sensors are placed, thus simulating the environmental conditions.

In this invention, the term test rig stands for an equipment that carries out component testing that is primarily used to verify and assess the requirements, capability and performance of the sensors, in this particular case of ultrasonic height pressure sensors.

According to the invention, the test rig comprises a support 14 fixed to center of a base plate 9 for receiving an airtight chamber 3. The airtight chamber 3 comprises a reflector 5 mounted at the bottom part, and a bead plate 1 on the top of the airtight chamber 3, and is mounted with the reflector 5 to said support 14 so that the longitudinal axis of the said chamber 3 is perpendicular to said base plate 9. A top plate 11 is arranged parallel to the base plate 9. A plurality of guiding elements is fixed between the base plate 10 and said top plate 11, being symmetrically placed in respect to the longitudinal axis of the airtight chamber 3. A mobile plate 10 is supported by the bead plate of the airtight chamber 3, vertically sliding along the guiding elements 12 within the distance between the bead plate 1 and top plate 11. An air supply connector 6 is mounted on said bead plate 1 being configured to generate a pressure above atmospheric pressure inside air chamber for moving the mobile plate 10 by the force exerted by inflated airtight chamber 3. In addition, by air supply connector the pressure of the air provided to the airtight chamber 3 it is controlled at predetermined pressures required for each ultrasonic height pressure depending on the vehicle to be mounted to or specific requirements of the components wherein the sensors are going to be used. Inside the airtight chamber 3 is created a pressure above atmospheric pressure. The mobile plate is configured with specific cavities for receiving all sensors mounted on the bead plate 1 and the air supply connector such that it is in direct contact with the bead plate 1 of the airtight chamber 3.

A plurality of contra pressure elements 13 are placed symmetrically in respect to the longitudinal axis of the airtight chamber for providing a counterforce to the mobile plate for the force exerted by inflated airtight chamber 3. Alternatively, depending on the various factors, such us the number of the ultrasonic height pressure sensors to be tested, the size of the climate chamber or specific requirements in respect to the sizes of the test rig, at least one contra pressure element 13 is placed along longitudinal axis of the airtight chamber 3 for providing a counterforce to the mobile plate for the force exerted by inflated airtight chamber 3.

At least 4 ultrasonic height pressure sensors 2 which have to be tested, are mounted on said bead plate, pneumatically connected to the airtight chamber 3, which are configured to measure the height between the bead plate 1 and reflector 5 plane during the inflating the airtight chamber 3, and to send the testing measurements to a processing unit.

On the base plate 9 is mounted a reference height sensor 7 for measuring the height between the base plate 9 and the mobile plate 10 during the inflating the airtight chamber 3. The reference height sensor 7 sends the said height measurements to the processing unit.

In order to measure the pressure inside airtight chamber 3, during the inflating the airtight chamber 3, it is provided a 30 reference pressure sensor 8 which is also mounted on said bead plate 1 being pneumatically connected to the airtight chamber 3. The reference pressure sensor 8 is configured to send the reference pressure measurements to said processing unit which is adapted to receive all measurements, to compare them and if there are in a prescribed tolerance interval to validate the respective ultrasonic height pressure sensors 2.

Thus, the processing unit is adapted to receive the reference pressure measurements from reference pressure sensor 8, and to 5 calculate the related predetermined reference tolerance pressure interval based on prescribed error value. The processing unit receives height measurements from reference height sensor 7, and calculates the reference height measurement from bead plate to the reflector 5 by taking into consideration the height of the 10 support 14. The processing unit further calculates the related predetermined reference height tolerance interval.

The predetermined tolerances intervals are established depending on the requirements for each ultrasonic height pressure sensor, depending on the vehicle where it is mounted or the 15 environmental working conditions.

The processing unit is further configured to receive the testing measurements from each of said ultrasonic height pressure sensors 2, and to compare them with said reference pressure and reference height measurements.

The processing unit determines if the testing measurements of each of ultrasonic height pressure sensors 2 are comprised in said predetermined reference tolerances intervals in respect to reference pressure and reference height measurements.

At least a non-volatile memory is configured to temporary store at least the results of the reference pressure and reference height measurements, reference tolerance pressure and reference height intervals based on prescribed error value and of the testing measurements, the results of comparisons between of the reference measurements, and of the testing measurements, and the validated measurements for each of the testing measurements in order to be used in the further steps of the methods.

In order to assure communication between said processing unit, non-volatile memory and said reference pressure sensor 8, and reference height sensor 7 a network it is provided.

If the testing measurements of an ultrasonic height pressure sensor 2 are comprised in references predetermined tolerances intervals in respect to said reference pressure and height measurements, each of the ultrasonic height pressure sensors 2 is validated by sending a message to a display of the test rig by said processing unit.

In order to simulate the working conditions, the air pressure inside the airtight chamber 3 may be varied up to a pressure of 13 bars.

In an embodiment of the present invention the airtight chamber 3 is an air bellow and said support 14 is a support piston configured to receive the piston 4 of the air bellow 3 as it is presented in the Fig. 1.

The air bellow 3 has attached at the upper part a bead plate 1 and is folded on a piston 4 at the bottom part in such a way that an airtight seal is formed between them. The piston 4 may be machined from a plastic material or any material able to form an airtight seal and to maintain its properties in the required conditions of pressure, humidity and temperature of a climatic chamber as they are described by the present invention.

The air bellow 3 supporting the ultrasonic height pressure sensors 2 may be a particular air bellow, having required dimensions and technical requirements for specific components or may be an air bellow used at the air suspension system of a vehicle, where several adaptations had been made in order to be used in a test rig according to the invention for simulating the real life conditions of operating the ultrasonic height pressure sensors 2.

As maybe seen in the Fig. 2, where is depicted the air bellow 3 with its special adaptations in order to be used in the test rig according to the invention, the bead plate 1 comprises 4 holes driven for mounting 4 mechanical connections, and 4 corresponding connectors in order to fit 4 ultrasonic height pressure sensors 2 to be tested in the related test rig.

On the piston 4 is placed a reflector 5 for receiving the ultrasonic wave 24. The ultrasonic height pressure sensors 2 are placed at the same distance from the center of the bead plate 1, and to each other, in such a way that the ultrasonic sound waves hit the reflector 5 without interfering between them.

The piston support 14 is bolted to center of the base plate 9 for supporting the piston providing a connection between the base plate 9 and the piston 4 and is machined to be connected with the bottom of the piston 4.

The bead plate 1 is connected to an air supply connector 6 for inflating the air bellow 3 configured to generate a pressure above atmospheric pressure inside the air bellow 3 for moving the mobile plate 10 by the force exerted by inflating the air bellow 3.

A reference pressure sensor 8 is placed also on the bead plate 1, configured to measure the air pressure inside the test chamber, for comparing and validating of the pressure values received from the ultrasonic height pressure sensors 2 to be tested. The reference pressure sensor 8 is configured to operate at extreme environmental conditions and it is also able to measure the temperature changes in the air bellow.

The reference height sensor 7 measures the height changes between the base plate 9 and the mobile plate 10 during the inflating and deflating of the air bellow. It maybe a draw wire sensor as shown in the Figure 3, however any other type of sensor maybe used if it would withstand in the environmental conditions, as they are figure out by the climatic chamber as described by the present invention. The reference height sensor 7 is bolted to the base plate 9 and the wire is fixed to the mobile plate 10 such that the height between the mobile plate and the base plate 9 to be measured in the same time during the testing the ultrasonic height pressure sensors 2, such that the variable height of the air bellow may be determined and compared with the height values determined by the ultrasonic height pressure sensors 2 to be tested.

The test rig also comprises at least 2 contra pressure elements placed symmetrically in respect to the longitudinal axe of the air bellow 2 for providing a counterforce to the mobile plate 10 for the force exerted by the air bellow 3 to the mobile plate 10 while it is inflated and a pressure above atmospheric pressure inside the air bellow 3 is created.

The base plate 9 may have various forms, for example may of a substantial rectangular form, the guiding elements 12 may be formed by four columns placed on the corners of the base plate 9, and the contra pressure elements maybe formed by two, three, four or more springs mounted between said base plate 9 and said mobile plate 10, placed symmetrically in respect to the longitudinal axis of the airtight chamber 3.

In the embodiment of the invention presented in the Figure 3 the contra pressure elements are 4 springs 13 fixed at one end to the base plate 9 and at the other end to the mobile plate 10. When air bellow is inflated, the bead plate 1 presses to the mobile plate 10 and both rise in such a way that the plane of the mobile plate 10 and the plane of the base plate 9 are always parallel. During the rise, the springs 13 provide a counter-force to the mobile plate so that simulates a weight on the air bellow 3.

The general behaviour for an air spring bellow is that it can support a load if a certain air pressure is inside it. If the air is introduced inside it or the load is reduced, the bead plate 1 will rise away from the piston 4, and vice versa when the air is vented, or the load is increased than the height between the bead plate and piston 4 is reduced. When the air bellow is deflated the springs 13 pull the mobile plate 10 down and it presses the bead plate 1 down. The parallel relation between the plane of the mobile plate 10 and the plane of the base plate 9, as described above, is also maintained while the air bellow 3 is deflated. The air bellow 3 is lifted by increasing the air pressure inside it, and vice versa lowered by decreasing the air pressure inside it.

In case that the air pressure inside the air bellow is high enough, the counterforce of the springs 13 are exceeded and the mobile plate 10 meets the top plate 11, which acts as a stopper for the movement of the mobile plate 10 and starting from this point an increase in pressure will no longer generate a change in height of the distance between the bead mobile plate 10 and base plate 9. The connections holding the top plate 11 and the columns 12 are configured so that they can withstand the force generated by the pressure inside the air bellow, and machined from a material which preserves its properties in the required conditions of pressure, humidity and temperature of a climatic chamber as they are described by the present invention.

During the inflating and deflating the air bellow 3, the height and pressure values received from each ultrasonic height pressure sensors 2 are compared to the values received and determined from the reference height sensor 7 and reference pressure sensor 8.

The height measurement of the air bellow 3, and the height measured by the ultrasonic height pressure sensors is determined by subtracting the height of the piston 4 and the height of the piston support 14 from the height measured by the reference height sensor 7, since the reference height sensor 7 measures the height between the base plate 9 and the mobile plate 10 while the ultrasonic height pressure sensors measures the height between the bead plate 1 and the reflector 5 inside the air bellow.

The test rig further comprises a processing unit, for 30 simplicity reasons it was not represented graphically in the figures, which is configured to receive the reference measurements from reference pressure sensor 8, and of said reference height sensor 7, to receive the testing measurements from ultrasonic height pressure sensors 2, and to compare them with said reference measurements. The processing unit determines if the testing measurements ultrasonic height pressure sensors 2 are comprised in a predetermined tolerances interval and in the affirmative, to validate the ultrasonic height pressure sensors

2 as valid to be used in the automotive field.

At least a non-volatile memory is configured to temporary store at least the results of the reference measurements, and the testing measurements, the results of comparisons between of the reference measurements, the results of the testing measurements, and the validated measurements for each of the measurable parameters of the ultrasonic height pressure sensors 2.

The test rig also comprises a network configured to assure communication between processing unit, non-volatile memory, and reference pressure sensor (8), and reference height sensor (7).

The height measured by the ultrasonic height pressure sensors may be tested at various conditions depending on the specific requirement of the components on which they are mounted. For example, at a maximum tested pressure of8 bars absolute pressure, a height between the ultrasonic element and the reflector 5 can be adjusted up to 320mm, and speed for reflector 5 movement up to 120mm/s.

The results may be stored in non-volatile memory and registered in order to apply at different automatic tests, such that a shorter time to validate the characteristics of the 25 ultrasonic height pressure sensors may be obtained.

In an embodiment of the test rig according to the invention as it is depicted in the Fig. 4, two airtight chambers, a lower airtight chamber 3, and an upper secondary airtight chamber 3.1, are mounted one above the other axially, to propagate the force from one airtight chamber to the other.

The mobile plate 10 is a dual mobile plate assembly 20 formed by two parallel plates, a lower mobile plate 20.1 and an upper mobile plate 20.2 fixed in between by a spacer 20.3. In this case the contra pressure elements are formed by a contra pressure secondary airtight chamber.l. mounted coaxially with airtight chamber 3 on a secondary piston 14.1. fixed to the upper mobile plate 20.2 of the dual mobile plate assembly 20, which is movable depending on the difference of air pressure between contra pressure secondary airtight chamber 3.1. and said airtight chamber 3.

The embodiment of the test rig according to the invention is able to change the height only by introducing or venting air into/from the airtight chambers. This means that the height is dependent on the pressure setting. The airtight chambers may also be air bellows specifically adapted to be used in the test rig according to the invention.

The dual air bellows test rig as described above allows the height to be changed without directly changing the pressure inside the target test air bellow. This would enable testing the scenario where the valves that supply the air bellow are closed and the height is changing, as would when driving on an uneven road.

The current test rigs from the prior art are limited by the fact that above a certain pressure the height remains constant and only the pressure can be further increased. This limitation is due to the availability shortage of certain components required for the test rig.

The objective of the embodiment is to change the height inside an air bellow without changing the mass of air inside the air bellow. This objective is achieved by changing the air pressure in the upper secondary air bellow 3.1. The dual mobile plate 20 will be moved whenever there is a difference of air pressure between upper and lower airtight chambers, secondary airtight chamber 3.1 and airtight chamber 3, respectively. When the supply of air is stopped the mobile plate 20 reaches a rest state since the air pressures inside both airtight chambers, upper secondary airtight chamber 3.1 and lower airtight chamber 3, are equal, being achieved an equilibrium state.

In the Fig. 5 it is presented the chassis of the embodiment of the test rig using two air springs bellows that are mounted one above the other axially, where the base plate 9 is fixed and it is the support for the whole test rig components.

For testing purposes, the bead plate 1 of a standard air spring bellow is modified to accept 4 ultrasonic height pressure sensors 2 and to have an extra mounting hole for a reference pressure sensor 8. The air is introduced/vented via the air supply connection 6. The rubber component of the air bellow 3 is attached to the bead plate 1 and then folded over piston 4, so that a seal surface 5 is created. This seal surface 5 is also used as a reflector for the ultrasonic waves 24 transmitted by each ultrasonic height pressure sensors 2.

On the base plate 9 four columns 12 are mounted at the corners, the support piston 14 is also mounted in the middle on the base plate 9. The top plate 11 is fixed on top of the columns 12 and has holes for the receiving the components mounted on the bead plate 1. The dual mobile plate assembly 20 is composed from 2 mobile plates, separated via spacers 20.3. This dual mobile plate assembly 20 can slide vertically on the columns 12 by means of Teflon bushings 15.

The planes of base plate 9, top plate 11, and lower mobile plate 20.1 and upper mobile plate 20.2 of the dual mobile plate assembly 20 are parallel.

The dimensioning of the embodiment of the test rig according to the invention is determined in such away that if an air bellow is at its maximum length, then the other air bellow is at its minimum length. The both the height changes induced in both air bellows 3, and 3.1 is determined using a single reference height measuring sensor 7. Thus, starting from the equilibrium position, by inflating and/or deflating one of the air bellows, it will result in the dual mobile plate assembly 20 to be moved up and/or down determining a force which will cause height and pressure changes in the other air bellow.

One of the main advantages of this embodiment is that the test rig can simulate the two main scenarios wherein the ultrasonic height pressure sensors 2 can be operated in the real conditions at the same time.

The first scenario, wherein the height and pressure vary greatly, which is created by introducing air inside the bellow via an open valve, thus the air pressure and height inside the air bellow being increased.

The second scenario, wherein the height and pressure varies depending on the road, which is created by increasing the pressure in the air bellow while the air valve is closed, and the height and pressure changes are induced in the air bellow by the up and down movement of the truck chassis when the vehicle is driven over an uneven road.

Yet, another advantage of this embodiment is that 8 ultrasonic height pressure sensors 2 may be tested in the same time, in particular 4 ultrasonic height pressure sensors 2 for each scenario.

In the real conditions the bead plate 1 plane may slide horizontally in relation to the reflector 5 plane, and even if the two planes are still parallel to each other, the ultrasonic waves 24 hit the reflector 5 perpendicularly, but in a different zone than it was designed. These two zones can overlap. In order to simulate the environmental conditions, an embodiment of the test rig according to the invention comprising an assembly for horizontally moving the bead plate 1 has been conceived of the inventors.

In this embodiment, the test rig further comprises means 16, and 19 for a predetermined movement of the bead plate 1 in the 30 horizontal direction, parallel to the reflector 5 plane.

In another non-limiting embodiment of the invention with reference with the Fig. 6, the means comprise at least 4 guiding support 16, each of them mounted on the middle of each side of the mobile plate 10 and 4 auxiliary air bellows 19a, 19b, 19c and 19d placed symmetrically around said air bellow 3 and in contact at least 4 guiding support 16, said 4 auxiliary air bellows 19a, 19b, 19c and 19d being connected to said air supply connector 6 for a predetermined horizontal movement of the bead plate 1 in the horizontal direction parallel to the reflector 5 by inflating of an air bellow, and deflating an oppose air bellow.

The guiding supports 16 are added to each auxiliary air bellow 19 to provide amounting point for the back end of the auxiliary air bellows 19. The auxiliary air bellows 19 are supported on both sides by guiding supports so that bead plate 1 plane is maintained parallel to the reflector plane. A mobile bumper 17 is mounted on the mobile plate 10, having the role to support the head plate 1 of the air bellow and to allow the bead plate 1 to slide in its plane.

While the mobile plate 10 slides vertically, the bottom side of the mobile bumper 17 allows the bead plate 1 to slide horizontally, while the auxiliary air bellows are being inflated or deflated. The mobile bumper 17 may be covered by a Teflon coating or any other material which allows the smoothly slide of the bead plate 1.

For simplicity reasons the reference height sensor 7 and the contra pressure elements 13, which in this case maybe formed by springs, are not represented graphically in the Figure 6. The reference airtight chamber 3.

The 4 auxiliary air bellows 19 are attached to the head plate 1 of the main air bellow 1, so that the centers of the auxiliary air bellows 19 horizontally push on the bead plate 1. The reflector 5 plane is fixed while the bead plate 1 is moved by the 4 auxiliary air bellows, whereas its plane is maintained parallel to the reflector plane. The 4 auxiliary air bellows 19 are placed equidistant to each other around the center of the bead plate 1, as shown in Fig.7. This positioning of the auxiliary air bellows 19 allows the bead plate to have a controlled slide in any direction in the same plane.

Fig. 9 depicts the bead plate 1 movement in relation to the reflector plane when auxiliary air bellow 19a is inflated at a higher pressure than auxiliary air bellow 19b. The bead plate 1 maybe displaced by a certain height so that the ultrasonic wave 24 emitted by the ultrasonic height pressure sensor 2 to still fall on the reflector plane as shown in the Fig. 9.

In order to test the ultrasonic height sensors, and the limit point beyond that the ultrasonic wave 24 no longer hits the reflector 5, the amount of lateral movement of the bead plate 1 may be predetermined depending on the type of airtight chamber 3, or air bellow 3 and on the scenarios in which the sensor would be required to operate.

The height between the bead plate 1 and the reflector 5 may be fixed or variable, depending on the requirements of the 15 ultrasonic height pressure sensor to be tested.

A position sensor 21 may be mounted to the bead plate 1 so that it can measure the sliding height of the bead plate 1 within the plane. For example, two draw wire sensors may be used for this purpose.

Under real world conditions the bead plate 1 plane may not be parallel in relation to the reflector plane and the ultrasonic waves 24 may not hit the reflector 5 perpendicularly.

In order to simulate the real conditions, the inventors conceived another non-limiting example comprising means for 25 tilting the plane of the reflector 5 with a predetermined angle in respect to the base plate.

The means comprise an additional movable plate 18, placed on auxiliary air bellows 19.1.a, 19.1.b, 19.1.c and 191.d which are connected to an additional air supply connector 25 for a predetermined tilt of said additional movable plate 18 in respect to the base plate 9 by inflating at least one air bellow, and deflating an opposite air bellow in respect to the longitudinal axe of the base plate.

The test rig further comprises a gyroscope for measuring the predetermined tilt of said movable plate 18 in respect to the base plate 9.

In the embodiment shown in Figs. 10 and 11, the additional movable plate 18 is placed on the base plate 9 by means of 4 5 auxiliary air bellows which may tilt additional movable plate 18 at a predetermined angle in respect to the base plate 9.

The embodiment has a particular advantage allowing the simulation of the pitch and roll movements of the piston 4 that can appear in a real situation due to the imperfections from the 10 road surface.

The piston 4 may pitch and/or roll by using the four auxiliary air bellows 19.1. The tilting of the plane of the reflector may be provided by various means, however the auxiliary air bellows 19.1. are cheaper, multiple variants being easier to be provided.

They also have the benefit that are easily integrated since they are controlled pneumatically and the ultrasonic height pressure sensors also requires an air supply and pneumatic control.

The commercially available air bellows can withstand to pressures comparable to the maximum pressure of the main air 20 bellow to which the ultrasonic height pressure sensors is attached to.

The piston 4 is also mounted on the support piston 14 which is then bolted to the additional movable plate 18. The additional movable plate 18 has 4 auxiliary air bellows 19.1. placed under it as shown in Figs 11 and 12. The four auxiliary air bellows 19.1. are bolted to the base plate 9, which may be made larger than shown in the figure and it may also be used as a support for other chassis components required for the test rig.

The auxiliary air bellows 19.1. may be placed on bushing 30 plates 26 machined by Teflon, for example as shown in Fig. 13. instead of being bolted to the mobile plate 10.

By letting the movable plate 18 to slide on the bushing plates 26, it is possible to move the pitch and roll center from the center of the movable plate 18 (point a) to the center of the piston 4 (point b). This extra degree of freedom for the movable plate 18 allows the reflector 5 to remain under the ultrasonic wave 24.

A mechanical stopper 22 is mounted on each of the auxiliary air bellows 19 to limit the sliding of the movable plate 18 on all 4 sides of it. The distance (c) between the movable plate 18 to the mechanical stopper 22 is computed depending on the height of piston 4 and support piston 14.

The pitch and/or roll can be achieved by inflating/deflating 10 one or more of the auxiliary air bellows 19.1. The auxiliary air bellows 19.1.can be inflated/deflated via their additional air supply connector 25.

The top plate 11 is fixed in a position parallel with the plane of the base plate 9. The pitch and/or roll movement maybe measured using an electronic gyroscope 23. Other measuring methods can also be used depending on the required conditions of the ultrasonic height pressure sensors 2.

The main advantage of this embodiment is that it will allow to simulate test conditions for an ultrasonic sensor when the 20 ultrasonic wave 24 will not always fall perpendicular on the reflector as it may happen in real working conditions.

Any embodiment of the test rig according to the invention may be placed in a climate chamber, wherein the temperature and humidity may be controlled fulfilling the conditions as described 25 above, simulating the environmental conditions.

In a second aspect of the invention it is provided-a method of using the test rig for testing the ultrasonic height pressure sensors according to any of the preceding claims in a climate chamber under predetermined variation of air pressure, humidity and temperature.

In a first step the test rig is mounted in the climate chamber wherein the predetermined temperature and humidity are maintained. The ultrasonic height pressure sensors 2 to be tested are mounted within the corresponding connecting holes within the bead plate of the airtight chamber 3. The airtight chamber 3 is supplied with air at a predetermined variation of air pressure by means of said air supply connector 6.

The pressure within the air bellow 3 is measured by the reference pressure sensor 8 and is calculated the related reference tolerance pressure interval based on prescribed error value by said processing unit. The reference pressure measurements and said reference tolerance interval are sent to said non-volatile memory.

The pressure within the air bellow 3 is also measured by the ultrasonic height pressure sensors 2 and the testing measurements are sent to said non-volatile memory. The height between the base plate 9 and mobile plate 10 is also measured by reference height sensor 7, and height measurements are sent to processing unit.

The processing unit determines the reference height measurements between the reflector 5 plane and the bead plate 1 by taking into consideration the height of said support 14 and determines the related tolerance height interval based on prescribed error value. The reference height measurements and reference height tolerances interval are sent to the at least one non-volatile memory.

The height between the reflector 5 plane and the bead plate I are measured by means of ultrasonic height pressure sensors 2, and testing height measureme=s are sent to the at least one 25 non-volatile memory.

The processing unit compares the referenced height measurement between the reflector plane and said bead plate I determined by processing unit and testing height measurements between the reflector plane and the bead plate 1 as measured by ultrasonic height pressure sensors 2. The processing unit further compares the reference pressure measurements within the air bellow 3 as measured by the reference pressure sensor 8 and the testing pressure measurement as measured by ultrasonic height pressure sensors 2.

The processing unit determines if the measured height between the reflector plane and the bead plate 1 is situated within the reference tolerance height interval based on prescribed error value, and if the measured pressure within said air bellow 3 as measured by the ultrasonic height pressure sensors 2 is situated within the reference pressure tolerance interval.

In the affirmative case, the processing unit validates the ultrasonic height pressure sensors 2 and displays the information on its display.

In order to simulate the real working conditions, the temperature may vary from-40°C up to +85°C, and/or the humidity up to 96%, depending on the specific requirements of the ultrasonic height pressure sensors.

The method according to invention it is also used for 15 calibrating the ultrasonic height pressure sensors to different air cavities.

It is obvious for those skilled in the art that the test rig may be adapted for testing any other type of sensor used for measuring the height and pressure inside and air cavity.

While the description of the method and the test rig were disclosed in detail in connection to preferred embodiments, those skilled in the art will appreciate that changes may be made to adapt a particular situation without departing from the essential scope to the teaching of the invention.

Claims

Claims 1. Test rig for testing ultrasonic height and pressure sensors (2) under predetermined variation of air pressure, humidity and temperature, said test rig comprising: -a base plate (9); -a support (14) fixed to center of the base plate (9) for receiving an airtight chamber (3); -said airtight chamber (3) comprising a reflector (5) mounted at the bottom part, and a bead plate (1) on the top of the airtight chamber (3), and being mounted with the reflector (5) to said support (14) so that the longitudinal axis of the said airtight chamber (3) is perpendicular to said base plate (9), -a top plate (11) arranged parallel to said base plate (9); -a plurality of guiding elements, at least 3 (12), fixed between the base plate (9) and to said top plate (11), symmetrically placed in respect to the longitudinal axis of the airtight chamber (3) -a mobile plate (10) supported by airtight chamber (3), vertically sliding along the guiding elements (12) within the height between the bead plate (1) and top plate (11), an air supply connector (6) mounted on said bead plate (1) configured to generate a predetermined variation of air pressure above atmospheric pressure inside airtight chamber (3) for moving the mobile plate (10) by the force exerted by inflated airtight chamber (3) and to control said pressure; a plurality of contra pressure elements (13; 3.1) placed symmetrically in respect to the longitudinal axis of the airtight chamber or at least one placed along longitudinal axis of the airtight chamber (3) for providing a counterforce to the mobile plate (10) for the force exerted by the airtight chamber (3) to the mobile plate (10) while it is inflated and a pressure above atmospheric pressure inside the airtight chamber (3) is created; -at least 4 ultrasonic height pressure sensors (2) to be tested, mounted on said bead plate (1) and pneumatically connected to the airtight chamber (3) being configured to measure the height between the bead plate (1) and reflector (5) during the inflating the airtight chamber (3), and to send the testing measurements to a processing unit; -a reference height sensor (7) mounted on said base plate (9) being configured to measure the height between the base plate (9) and the mobile plate (10) during the inflating the airtight chamber (3), and to send the height measurements to said processing unit; -a reference pressure sensor (8) mounted on said bead plate (1) pneumatically connected to the airtight chamber (3), being configured to measure the pressure inside airtight chamber (3), during the inflating the airtight chamber (3), and to send the reference pressure measurements to said processing unit; -said processing unit being adapted * to receive the reference pressure and reference height measurements from said reference pressure sensor (8), and of said reference height sensor (7); * to receive the testing measurements from each of said ultrasonic height pressure sensors (2), and to compare them with said reference pressure and height measurements; * to determine if the testing measurements of each of said ultrasonic height pressure sensors (2) are comprised in a predetermined tolerances interval in respect to said reference pressure and height measurements; -at least a non-volatile memory configured to temporary store at least: * the results of the reference pressure and height measurements, and of the testing measurements; * the results of comparisons between of the reference measurements, and of the testing measurements; * the validated measurements for each of the testing measurements; -a network configured to assure communication between said processing unit, non-volatile memory, said reference pressure sensor (8), and said reference height sensor (7); said test rig being configured such that a message for each of the ultrasonic height pressure sensors (2) is sent to a display by said processing unit if the testing measurements of respective ultrasonic height pressure sensor (2) are comprised in predetermined tolerances intervals in respect to said reference pressure and height measurements.
2. Test rig according to claim 1 wherein the predetermined variation of the air pressure created through air supply connector (6) is situated up to a pressure of 13 bars measured 20 within the airtight chamber (3).
3. Test rig for testing ultrasonic height pressure sensors (2) according to any previous claim wherein said airtight chamber (3) is an air bellow (3) and said support (14) is a support piston (14) configured to receive the piston (4) of said air bellow (3).
4. Test rig for testing ultrasonic height pressure sensors (2) according to any of the preceding claims, wherein the base plate (9) has a substantial rectangular form, and guiding elements (12) are formed by four columns (12) placed on the corners of the base plate (9).
5. Test rig for testing ultrasonic height pressure sensors (2) according to any of the preceding claims, wherein the contra pressure elements (13) are formed by two springs mounted between said base plate (9) and said mobile plate (10), placed symmetrically in respect to the longitudinal axis of the airtight chamber (3).
6. Test rig for testing ultrasonic height pressure sensors (2) according to the claims from 1 to 4, wherein the contra pressure elements (13; 3.1) are formed by 4 springs (13) placed symmetrically in respect to said airtight chamber (3) between said base plate (9) and said mobile plate (10).
7. Test rig for testing ultrasonic height pressure sensors (2) according to claims from 1 to 4, wherein the mobile plate (10) is a dual mobile plate assembly (20) formed by two parallel plates, a lower mobile plate (20.1) and a upper mobile plate (20.2) fixed in between by a spacer (20.3) and contra pressure elements are formed by a contra pressure secondary airtight chamber (3.1.) mounted coaxially with said airtight chamber (3) on a secondary piston support (14.1.) fixed to said dual mobile plate assembly (20) which is movable depending on the difference of air pressure between contra pressure secondary airtight chamber (3.1.) and said airtight chamber (3).
8. Test rig for testing ultrasonic height pressure sensors (2) according to the claims from 1 to 6, wherein the test rig further comprises means (16, 19a, 19b, 19c and 19d) for a predetermined 30 horizontal movement of the bead plate (1) in the horizontal direction parallel to the plane of reflector (5).
9. Test rig for testing ultrasonic height pressure sensors (2) according to claim 8, wherein said means comprise at least 4 guiding support (16), each of them mounted on the middle of each side of the mobile plate (10) and at least 4 auxiliary air bellows (19a, 19b, 19c and 19d) placed symmetrically around said airtight chamber (3) and in contact with at least 4 guiding support (16), 5 said 4 auxiliary air bellows (19a, 19b, 19c and19d) being connected with a secondary air supply connector (25) for a predetermined horizontal movement of the bead plate (1) in the horizontal direction parallel to the reflector (5) by inflating an air bellow, and deflating an air bellow placed opposed in 10 respect to the longitudinal axis of said airtight chamber (3).
10. A test rig for testing ultrasonic height pressure sensors (2) according to the claims 8 or 9 wherein the test rig further comprises a position sensor for measuring the horizontal movement 15 of the bead plate (1) in respect to the base plate (9).
11. Test rig for testing ultrasonic height pressure sensors (2) according to the claims from 1 to 4, wherein the test rig further comprises means for tilting the plane of the reflector (5) with 20 a predetermined angle in respect to the base plate (9).
12. Test rig for testing ultrasonic height pressure sensors (2) according to the claim 11 wherein said means comprises a plurality of auxiliary air bellows (19.1.a, 19.1.b, 19.1.c and 19.1.d), at least four, placed symmetrically on the base plate (9) and a movable plate (18), placed on said auxiliary air bellows (19.1.a, 19.1.b, 19.1.c and 19.1.d), said auxiliary air bellows (19.1.a, 19.1.b, 19.1.c and 19.1.d) being connected to an additional air supply connector (25) for a predetermined tilt of said movable plate (18) in respect to the base plate (9) by inflating the auxiliary air bellows (19.1.a, 19.1.b, 19.1.c and 19.1.d) and deflating the auxiliary air bellows (19.1.a, 19.1.b, 19.1.c and 19.1.d) placed in opposite direction in respect to the longitudinal axis or the transversal axis of the base plate (9).
13. Test rig for testing ultrasonic height pressure sensors (2) according to claim 9 wherein further the test rig further comprises a gyroscope for measuring the predetermined tilt of 5 said movable plate (18) in respect to the base plate (9).
14. Method of using the test rig for testing the ultrasonic height pressure sensors according to any of the preceding claims under predetermined variation of air pressure, humidity and temperature characterized in that the following steps are carried out: -mounting said test rig in a climate chamber wherein said predetermined variations of temperature and humidity are maintained; -mounting the ultrasonic height pressure sensors (2) to be tested within the corresponding connecting holes within the bead plate of the airtight chamber (3); -supplying the airtight chamber (3) with the air at a predetermined pressure by means of said air supply connector (6); -measuring the pressure within the airtight chamber (3) by the reference pressure sensor (8), and calculating the related reference tolerance pressure interval based on prescribed error value by said processing unit and sending the reference pressure measurements and said reference tolerance interval to said non-volatile memory; -measuring the pressure within the airtight chamber (3) by the ultrasonic height pressure sensors (2) and sending the testing measurements to said non-volatile memory; -measuring the height between the base plate (9) and mobile plate (10) by reference height sensor (7), and sending said height measurements to said processing unit; -determining the reference height measurements between the plane of the reflector (5) and the bead plate (1) by taking into consideration the height of said support (14), and determining the related tolerance height interval based on prescribed error value by means of said processing unit and sending the reference height measurements and reference height tolerances interval to the at least one non-volatile memory; -measuring the height between the reflector (5) plane and the bead plate (1) by means of ultrasonic height pressure sensors (2), and sending testing height measurements to the at least one non-volatile memory; comparing by means of said processing unit: * of the referenced height measurement between the reflector plane and said bead plate (1) determined by said processing unit and testing height measurement between the reflector plane and the bead plate (1) as measured by ultrasonic height pressure sensors (2); * of the reference pressure measurements within the airtight chamber (3) as measured by the reference pressure sensor (8) and the testing pressure measurement as measured by ultrasonic height pressure sensors (2); determining by means of said processing unit if the following conditions are fulfilled: * if the measured height between the reflector plane and the bead plate (1) is situated within the reference tolerance height interval based on prescribed error value; * if the measured pressure within said airtight chamber (3) measured by the ultrasonic height pressure sensors (2) is situated within the reference pressure tolerance interval; -in the affirmative case, validating the ultrasonic height pressure sensors (2) by means of said processing unit and displaying the information on its display.
15. Method of using the test rig for testing the ultrasonic height pressure sensors according to any of the preceding claims wherein the temperature varies from-40°C up to +85°C, and/or the 5 humidity is up to 96%.