TIRE TESTER

Description

[0001] The present invention relates to a testing device, which is a tire testing device, comprising a test chamber in which a tire can be arranged as the measurement object to be tested, a pressure loading unit for changing the pressure in the test chamber and at least one measuring head for measuring a measurement object arranged in the test chamber at different pressure values ​​generated by the pressure loading unit.

[0002] The present invention particularly relates to testing devices that measure the test object interferometrically, for example, using shearography. Phase images recorded at different pressure values ​​and thus different loading conditions of the test object are evaluated to determine the deformation of the test object between the two conditions. In particular, this allows for the detection of defects inside the test object that locally lead to a different expansion behavior of the test object under the change in pressure.

[0003] In a tire testing device, the tire is measured in the test chamber at different pressure values ​​using the measuring head in order to detect defects in the tire, especially defects inside the tire.

[0004] Conventional tire testing devices usually operate with negative pressure. This means that after the test object is introduced into the test chamber, the pressure loading unit lowers the pressure inside the test chamber and then raises it back to ambient pressure. The measurement of the test object can be performed during the negative pressure generation phase (i.e., when the negative pressure is increasing), during the negative pressure reduction phase (i.e., when the negative pressure is decreasing), or during both phases.

[0005] According to the state of the art, the negative pressure in the test chamber is generated by a pump connected to the test chamber via pipes. The negative pressure is released either by opening an inlet, through which air flows from the ambient air into the test chamber due to the pressure difference, or by actively pumping air into the test chamber.

[0006] Such tire testing devices are known from the documents DE102013010402A1, EP2851670B1, DE102005049607A1, EP 3 521 796 A1, DE10102232C2, DE102006015123B4, EP1959227B1, DE 10 2006 061 003 B4 and DE 10 2013 102 296 B4.

[0007] US 2018 / 372603 A1 describes a test device for laminates. US 2016 / 239027 A1 describes a pressure compensation system for submarines. DE 40 02 856 A1 shows a valve.

[0008] The inventors of the present invention have recognized a number of disadvantages in the use of a vacuum pump to generate negative pressure. For example, generating negative pressure using a vacuum pump leads to air turbulence in the test chamber, which can cause movement or vibration of the test object and thus to poor image quality. Therefore, settling times may also be necessary, which, however, leads to a longer test time. Furthermore, precise control of the vacuum profile is not possible, potentially resulting in poorer image quality. Furthermore, the use of a vacuum pump leads to a comparatively high noise level and high energy consumption. Despite these disadvantages, vacuum pumps have been used in testing devices of this type for decades. An alternative has not been apparent until now. The object of the present invention is to provide an improved tire testing device.

[0009] According to the invention, this object is achieved by a tire testing device according to claim 1. Preferred embodiments of the present invention are the subject of the subclaims.

[0010] The present invention comprises a testing device, which is a tire testing device, with a test chamber, a pressure loading unit for changing the pressure in the test chamber, and at least one measuring head for measuring a test object arranged in the test chamber at different pressure values ​​generated by the pressure loading unit. According to the invention, the pressure loading unit changes the test chamber volume while excluding air from the environment in order to change the pressure in the test chamber. The inventive design of the pressure loading unit can improve or avoid at least some of the problems mentioned above with regard to the use of vacuum pumps. For example, the air flow problem and its negative influence on image quality can be improved or eliminated because there is significantly less air movement.Depending on the design, the pressure profile, especially the vacuum profile, can also be controlled more precisely. Furthermore, it is possible to reduce cycle times and operate with greater efficiency and lower noise emissions.

[0011] According to the present invention, the pressure loading unit comprises a wall element of the test chamber which is movable relative to the rest of the test chamber structure and by means of which movement the test chamber volume can be changed.

[0012] The desired pressure in the test chamber can therefore be adjusted by adjusting the position of the wall element along its stroke. In one possible embodiment of the invention, the test chamber volume and thus the pressure in the test chamber can be controlled by the position of the movable wall element.

[0013] The use of a movable wall element according to the invention results in particular in the advantages already described above of lower air flows within the test chamber, better control of pressure changes, lower energy consumption and lower noise generation.

[0014] In one possible embodiment of the present invention, the movable wall element is sealed to the rest of the test chamber structure. The seal can be achieved by a sliding seal or a flexible seal to maintain the seal against the environment during movement of the wall element. In one possible embodiment of the present invention, the movable wall element is sealed to the rest of the test chamber structure by a flexible sealing element, in particular a bellows. Furthermore, if a shorter stroke is sufficient, a flexible sealing element made of foam rubber, for example, could also be used.

[0015] The movable wall element can be designed as a rigid wall element which is connected to the rest of the test chamber structure via a sliding seal or a flexible seal.

[0016] In one possible embodiment of the present invention, the movable wall element is formed by a flexible membrane that is sealed to the rest of the test chamber structure. Depending on the required travel, a flat membrane, a corrugated membrane, a plate membrane, and / or a rolling membrane can be used. The membrane can be made, for example, of a fabric-reinforced elastomer.

[0017] In one possible embodiment of the present invention, the movable wall element, when projected into a plane extending perpendicular to its direction of movement, has an area of ​​at least 5% of the square of the cube root of the volume of the test chamber. The square of the cube root of the volume of the test chamber corresponds to the area of ​​a side wall of an imaginary test chamber that has the shape of a cube and the same volume as the actual test chamber. Therefore, according to this embodiment, the area of ​​the movable wall element bears at least 5% of the wall area of ​​such a side wall of a cube with the same volume as the test chamber.

[0018] Preferably, the area of ​​the movable wall element when projected into a plane extending perpendicular to its direction of movement is at least 10%, more preferably at least 30% of the square of the cube root of the volume of the test chamber.

[0019] By selecting the appropriate size of the wall element, the required stroke can be reduced and any air turbulence that may occur can be reduced.

[0020] The upper size of the wall element is only limited by the size of the wall of the test chamber in which the wall element is arranged.

[0021] In one possible embodiment of the present invention, the movable wall element, when projected onto a plane extending perpendicular to its direction of movement, has an area of ​​at least 0.05 m², preferably at least 0.2 m², more preferably at least 0.5 m². These dimensions indicate preferred dimensions for tire testing devices.

[0022] In one possible embodiment of the present invention, the testing device has a drive via which the movable wall element can be moved. In particular, the drive is a servomotor via which the position of the movable wall element can be adjusted along its stroke.

[0023] Preferably, the testing device has a control system which controls the drive in such a way that the movable wall element moves along its stroke path according to a predetermined path-time curve and thereby generates a defined pressure-time profile in the test chamber.

[0024] Preferably, the testing device has a control system which controls the drive and the at least one measuring head in such a way that the measuring object is tested by the at least one measuring head in at least one measuring cycle in which the pressure in the pressure chamber is changed by a movement of the movable wall element.

[0025] In particular, the drive and / or the measuring head can be controlled automatically so that the measuring object is tested automatically.

[0026] A measuring cycle preferably comprises at least a first movement of the movable wall element from an initial position in which ambient pressure prevails inside the test chamber, into a loading position in which the pressure inside the test chamber has been changed in a first direction by the movement of the movable element, and at least a second movement by which the pressure inside the test chamber is changed in the opposite direction back to the ambient pressure.

[0027] Preferably, a motion profile is stored in the control system, with which the movable element is moved in a targeted manner along its stroke. This allows a corresponding pressure profile to be generated inside the test chamber.

[0028] A particular advantage of the present invention is that by controlling the pressure level within the test chamber by moving the movable wall element across its stroke range, the transition between a loading phase and a release phase can be controlled without the occurrence of load peaks. When using a vacuum pump, however, pressure pulses regularly occurred when switching the pumping direction, which led to undesirable vibration excitation in the test object.

[0029] In one possible embodiment of the present invention, the drive is a linear drive. This enables particularly simple control of the test chamber volume and thus the pressure within the test chamber. For example, the linear drive can be a spindle drive. Alternatively, the use of a pneumatic or hydraulic cylinder would also be conceivable.

[0030] In one possible embodiment of the present invention, the drive is an electric drive, in particular an electric motor drive.

[0031] In a preferred embodiment of the present invention, the drive and / or the pressure load unit comprises a measuring arrangement by which the position of the movable wall element along its stroke can be determined. This can, for example, be an encoder integrated into the drive.

[0032] In one possible embodiment of the present invention, the movable wall element is arranged in the area of ​​the ceiling of the test chamber. This allows for easy retrofitting of existing test devices. Furthermore, no significant changes to the design of existing test devices are required. For example, the existing ceiling of the test chamber can be supplemented or replaced by the movable wall element.

[0033] However, the movable wall element can also be arranged in any other wall areas, in particular in the area of ​​one or more side walls, or in the floor of the test chamber.

[0034] In one possible embodiment of the present invention, movable wall elements are provided on opposite sides of the test chamber. These are preferably configured as described above. The wall elements are preferably controlled synchronously. Control is preferably symmetrical. By arranging two movable wall elements on opposite sides of the test chamber, the occurrence of unwanted air turbulence within the test chamber can be further reduced.

[0035] The inventive change in the pressure in the test chamber by changing the volume allows a significant reduction in energy consumption even without further measures, since the high friction losses that occur when using pumps can be avoided.

[0036] In one possible embodiment of the present invention, the testing device further comprises an energy recovery unit for recovering the energy released by depressurizing the test chamber. This allows the energy consumption of the testing device to be significantly reduced.

[0037] In a possible embodiment of the present invention, the energy stored in the energy recovery unit is used to renew the pressure load on the test chamber.

[0038] In particular, at least part of the energy released during the pressure relief of the test chamber will be stored in the energy recovery unit and then used to pressurise the test chamber via the pressure loading unit.

[0039] In one possible embodiment of the present invention, energy recovery can occur via the drive of the pressure loading unit, for example, by converting the released energy upon pressure relief and feeding it into a storage device. In the case of an electric drive, this can act as a generator, for example, and the energy can be stored in an electrical energy storage device. In the case of a hydraulic or pneumatic drive, the energy recovered by the drive can be stored in a pneumatic or hydraulic storage device.

[0040] In a further embodiment, the energy recovery unit can support the drive of the pressure relief and / or act on the movable wall element in parallel thereto.

[0041] In one possible embodiment of the present invention, the energy recovery unit comprises a force compensator, which generates a counterforce to the compressive force acting on the pressure loading unit, and in particular on the movable element, in the loaded state. This reduces the force that must be applied by the drive.

[0042] In one possible embodiment of the present invention, the energy recovery unit may comprise at least one spring unit, in particular an air spring unit. The spring unit may comprise one or more springs that are tensioned when the test chamber is depressurized and support the drive when pressure is applied.

[0043] In one possible embodiment of the present invention, the energy recovery unit can comprise at least one linearly operating force element. In particular, this can be a spring element, in particular an air spring element, in particular a spring element whose length can be varied depending on the applied force.

[0044] In a possible embodiment of the present invention, the linearly operating force element is deflected on the movable wall element in such a way that the proportion of the forces of the energy recovery unit effectively acting on the movable element in the direction of movement is adapted to the static forces acting on the movable wall element in the respective lifting position and preferably at least partially and more preferably largely compensates for these.

[0045] In one possible embodiment of the present invention, a movable wall element of the pressure loading unit is connected to at least one linearly operating force element, in particular a spring element, such that the force direction of the force element changes relative to a direction of movement of the movable wall element over the stroke range of the movable wall element. This allows a corresponding change in the force components acting in the direction of movement.

[0046] In a preferred embodiment, the angle between the direction of force of the force element and the direction of movement of the movable wall element increases when the wall element moves in the direction of unloading and decreases when it moves in the direction of loading. As a result, the portion of the force generated by the force element acting in the direction of movement is greater in a first, loaded position than in a second, unloaded position.

[0047] In one possible embodiment of the present invention, the movable wall element of the pressure loading unit is connected to the test chamber structure via at least two force elements, particularly in the form of spring elements, such that the components of the forces generated by the force elements acting transversely to the direction of movement of the movable wall element cancel each other out, and the components acting in the direction of movement are added together. For example, a symmetrical arrangement of the multiple force elements with respect to a central axis of the wall element is conceivable.

[0048] In one possible embodiment of the present invention, the pressure loading unit generates a negative pressure in the test chamber. In particular, the pressure loading unit is designed to increase the volume of the test chamber while keeping the atmosphere sealed off, in order to reduce the pressure inside the test chamber from the ambient pressure.

[0049] In particular, the movable wall element can be moved outwards to increase the volume of the test chamber.

[0050] The testing device according to the invention is, as already mentioned, a tire testing device. This can be designed as already described above with regard to the prior art.

[0051] Within the test chamber, the tire testing device can have a support surface on which the tire rests. In particular, the tire can rest with its sidewall on a support surface. Alternatively, it would be conceivable for the tire to rest with its bead on retaining elements.

[0052] In one possible embodiment of the present invention, the measuring head is arranged within the test chamber.

[0053] Preferably, at least one measuring head can be moved into the interior of the tire via a travel arrangement.

[0054] In one possible embodiment of the present invention, the measuring head is rotatable relative to the tire about the tire's axis in order to inspect the tire's circumference in sections at multiple rotational positions. Alternatively or additionally, multiple measuring heads can be used to inspect different sections of the tire's circumference.

[0055] According to one possible embodiment of the present invention, the testing device can be a testing device operating on an interferometric measuring principle, wherein the testing device preferably operates shearographically. The measuring head can be an interferometric measuring head, in particular a shearographic measuring head.

[0056] The present invention further comprises a method for testing a measurement object with a testing device as described above, comprising the steps: Placing the measuring object into the test chamber of the testing device and measuring the measuring object arranged in the test chamber at different pressure values.

[0057] The method is characterized in that the change in pressure in the test chamber occurs by changing the test chamber volume while excluding air from the environment.

[0058] The method according to the invention results in the same advantages as those already described above with regard to the testing device according to the invention.

[0059] The method according to the invention is preferably carried out as already described above with regard to the testing device.

[0060] The present invention will now be described in more detail with reference to embodiments and drawings.

[0061] Showing: Fig. 1 shows an embodiment of a testing device according to the invention in a schematic side view, Fig. 2 shows an embodiment of the testing device according to the invention in a perspective view, wherein the pressure loading unit is shown in an unloaded state, Fig. 3 shows the Fig. 2 shown embodiment, wherein the pressure loading unit is shown in a pressure loading state, Fig. 4a and 4b the pressure loading unit of the in Fig. 2 and 3 shown test device in a pressure load state and an unloaded state, Fig. 5a and 5b show an embodiment of the pressure loading unit with an energy recovery unit in an unloaded state in a perspective view and a sectional view, and Fig. 6a and 6b show the embodiment of the pressure loading unit with an energy recovery unit in a pressure load state in a perspective view and a sectional view.

[0062] Figure 1 shows a testing device according to the invention in a schematic side view. The testing device 1 has a test chamber 6 in which a test object 5 to be tested can be arranged. In the exemplary embodiment, a support surface 4 is provided within the test chamber 6, on which the test object 5 is arranged. Furthermore, at least one measuring head 10 is provided, via which the test object 5 arranged in the test chamber 6 is measured.

[0063] In the exemplary embodiment, the testing device has door elements 3, via which the test chamber can be opened and closed to allow test objects to be introduced into and removed from the test chamber. In the exemplary embodiment, two door elements 3 are arranged in opposite side wall areas of the test chamber. This allows test objects to be introduced into the test chamber on one side and removed from the test chamber on the other side. However, any other configurations of the test chamber are also conceivable.

[0064] The testing device has a pressure loading device 20, via which the pressure inside the test chamber 6 can be changed in a controlled manner. The pressure loading unit 20 comprises a movable wall element 7, via the movement of which the volume of the test chamber 6 can be changed in order to thereby change the pressure within the test chamber.

[0065] For this purpose, a drive 9 is provided, via which the movable wall element 7 can be moved along a stroke path in order to control the internal volume of the test chamber 6 and thereby the pressure within the test chamber via the position of the movable wall element.

[0066] The movable wall element 7 is connected to the rest of the test chamber structure via a seal 8. The movement of the movable wall element 7 occurs while the test chamber is sealed from the environment, so that the change in the internal volume results in a corresponding change in the pressure inside the test chamber.

[0067] In the exemplary embodiment, the drive 9 is a linear drive, with the movable element being movable linearly along a stroke. The stroke and thus the direction of movement are perpendicular to the main extension plane of the wall element 7 in the exemplary embodiment.

[0068] However, other configurations of the stroke or drive are also conceivable. For example, it would be conceivable to arrange the wall element in a flap-like manner, pivotable via a corresponding seal on the rest of the test chamber structure, and to provide a corresponding drive that pivots the wall element.

[0069] In the exemplary embodiment, drive 9 is a servo drive, which can be used to control the position of the lifting element along the stroke. This allows the pressure curve within the test chamber to be precisely controlled.

[0070] The stroke depends on the pressure change required for the test, particularly the required negative pressure, and on the tightness of the test chamber. Since the air seal under which the change in the test chamber volume occurs is never complete, a correspondingly larger stroke must be provided than that required for complete air seal. For example, an additional factor of 10 to 20% of the stroke can be provided.

[0071] The volume of the test chamber is inversely proportional to the pressure in the measurement chamber. Therefore, for example, a pressure reduction of approximately 0.05 bar requires a volume increase of approximately 5% (although the relationship is not truly linear). For example, if the test chamber has a volume of 5 m3 in a possible embodiment, this should be able to be increased by 0.3 m3 to provide a negative pressure of approximately 50 mbar (taking into account any leaks).

[0072] In the Figure 1 In the test device shown, the at least one measuring head 10 is preferably an interferometric measuring head, in particular a shearography measuring head. Laser light is radiated onto the surface of the tire and reflected in two partial beams onto a sensor via an optics system of the measuring head, which includes a shearing element. This allows phase images of the measurement object to be recorded.

[0073] A control system of the testing device controls the compression loading unit 9 and the at least one measuring head 10 in such a way that images are generated for multiple compression loading conditions of the test object, which are then evaluated by the control system to test the test object. In particular, phase difference images are generated that show the deformation of the test object due to the compression loading or unloading.

[0074] During a measurement cycle, at least one pressure loading and at least one pressure release preferably occur. Images can be taken during the pressure loading, during the pressure release, or during both phases.

[0075] The testing device can have a plurality of measuring heads to test multiple sectors of the test object simultaneously. Preferably, at least some of the measuring heads can be moved into the interior of the tire to test the inside of the tire. Furthermore, measuring heads can be provided to test the sidewalls of the tire from the outside.

[0076] In the Figure 1 The test device shown is a tire testing device for testing a tire 5.

[0077] In one possible embodiment, the measuring head assembly can be rotatable about a rotation axis that coincides with the rotation axis of the tire in order to test the tire in multiple positions in the circumferential direction. However, the measuring heads can be arranged in a rotationally fixed manner relative to the tire support 4.

[0078] In the Figure 1In the exemplary embodiment shown in a schematic diagram, the pressure loading unit 20 is arranged in the region of the ceiling of the test chamber 6. However, it could equally well be arranged in the region of one of the side walls or in the region of the floor. Furthermore, several pressure loading devices could be provided in opposite wall areas of the test chamber.

[0079] Figure 2 - 4 show a concrete example of a testing device and the pressure load unit used in it. The concrete example corresponds in its structure to the one already shown in Figure 1 shown basic design, so that first the description should be Figure 1 is referred to.

[0080] In Figure 2 the test device is shown in a perspective view from the outside. Fig. 2 shows in addition to the Fig. 1The elements of the test device shown include a control cabinet 14 with the control of the test device, as well as an input / output unit 15 for the control, in particular with a display and input elements. Furthermore, the specific design of the door elements 3 is shown as sliding doors operating in the vertical direction.

[0081] Figure 2 also shows a concrete structural design of the pressure loading unit. The movable wall element 7 is connected to a wall area of ​​the test chamber arrangement 6 via a flexible seal 8. In the exemplary embodiment, the movable wall element 7 is connected to a ceiling panel 13 of the test chamber arrangement via the flexible seal 8. The flexible seal 8 therefore allows movement of the movable wall element 7 relative to the test chamber arrangement and thereby a change in the test chamber volume while excluding air from the environment.

[0082] In the exemplary embodiment, a bellows is used as the seal 8. This allows for a relatively large stroke. The wall element 7 is designed as a rigid plate, so that the volume change generated by a movement of the wall element essentially corresponds to the base area of ​​the flexible wall element 7 multiplied by the stroke.

[0083] Alternatively, it would be conceivable to use a membrane as the movable wall element 7.

[0084] In the exemplary embodiment, a linear drive 9 is used as the drive, for example, a spindle drive with an electric drive motor. The drive 9 is arranged on a portal element 12, which is connected to the test chamber arrangement and absorbs the forces generated during the movement of the movable wall element 7. In the exemplary embodiment, the portal element 12 is attached to the ceiling plate 13 of the test chamber on opposite sides of the movable wall element 7.

[0085] In the exemplary embodiment, the movable wall element has a circular base. This allows the seal 8 to absorb the forces occurring particularly well.

[0086] In particular, the design is such that the pressure load on the seal 8 and in particular on the bellows is radially outward, since in this direction the pressure forces occurring can be absorbed by the seal and in particular the bellows.

[0087] As in Figure 5 and 6 As can be seen, the static test chamber structure has a corresponding opening, which is covered by the movable wall element.

[0088] In the exemplary embodiment, the pressure loading unit generates a negative pressure by moving the movable wall element 7 outwards with the test chamber closed in order to increase the volume of the test chamber. The pressure is relieved by moving the movable element 7 back to its starting position. The starting position is in Figure 2 , 4b and 5 shown the loaded position in Figure 3 , 4a and 6 .

[0089] In one embodiment, the pressure change is carried out, in particular by generating a negative pressure, in order to make the defects of the measuring object visible by means of shearography.

[0090] For example, during the test sequence, the pressure in the test chamber can be reduced by 5 mbar to 100 mbar, in particular by 15 mbar to 75 mbar, for example, by 25 to 50 mbar compared to the ambient pressure and then adjusted again. The shearography sensor captures multiple images during the pressure reduction phase or during the readjustment to ambient pressure, or - in the case of a symmetrical load cycle, for example - during both phases. From the captured images, a shearogram of the observed tire area can be calculated, which can be used to identify the tire's defects.

[0091] This inventive solution allows the airflow problem described above and its negative impact on image quality to be reduced or even completely eliminated, as there is significantly less air movement. The vacuum / time behavior (vacuum profile) can be precisely controlled via the lid position (servo axis). This – possibly in conjunction with new evaluation algorithms – can achieve better image quality.

[0092] Furthermore, the testing device according to the invention can operate much faster than known testing devices. The evacuation time can be significantly reduced.

[0093] Furthermore, the inaccurate switching from evacuation to ventilation in conventional testing devices with vacuum pumps can be better controlled, which also contributes to improving image quality and shortening the testing time.

[0094] Compared to known testing devices, the testing device according to the invention also offers significantly better efficiency. This can result in energy savings of approximately 50% even without additional measures. Noise pollution is also reduced.

[0095] In Figure 5 and 6 An energy recovery unit is also shown, through which the energy released during pressure relief can be stored and reused for the pressure load.

[0096] In the exemplary embodiment, the energy recovery unit is designed as a force compensator that counteracts the compressive force. The force compensator is preferably designed to compensate for both static weight forces and static compressive forces.

[0097] In the exemplary embodiment, several compression springs 31 are provided for this purpose, which are pivotably connected with one side to the movable wall element 7 and with the other side to the test chamber structure. Due to this arrangement, the angle α between the force direction 31' of the compression springs 31 and the movement direction 9' of the movable element changes over the stroke. In the Figure 6 In the loaded position shown, the angle α is smaller than in the Figure 5 shown unloaded position, so that the component of the counterforce generated by the compression springs, which acts in the direction of movement, is larger.

[0098] The multiple compression springs 31 are arranged symmetrically, so that the force components acting transversely to the direction of movement 9' of the movable element 9 cancel each other out. The force components acting in the direction of movement, however, add up.

[0099] The design can be easily solved using spring assemblies or gas pressure springs. In the example shown, these are mounted in such a way that an increasing counterforce is exerted on the lid as it rises.

[0100] Preferably, the force compensator is designed such that this counterforce is equal to the sum of the movable mass and the resulting negative pressure, so that the static forces acting on the movable wall element are in equilibrium over the stroke.

[0101] In the exemplary embodiment, several star-shaped springs 31 are provided for this purpose, the outer ends of which are articulated via bearing points 32 to a frame 33 of an opening in a wall of the test chamber and the inner ends of which are articulated via bearing points 34 to the movable wall element 7, so that the angle of the springs to the direction of movement of the movable element changes depending on the position of the movable wall element 7.

[0102] Preferably, the angles are selected such that the characteristic curve of the springs essentially corresponds to the characteristic curve of the movable element. This characteristic curve results from the static weight of the movable element and the compressive force acting on it due to the negative pressure.

[0103] Energy savings can be further improved by equipping the system with an energy recovery unit or an additional force compensator. A force compensator can cancel out the process forces generated by the moving masses. This reduces the required energy consumption to a fraction of that of conventional testing devices (approximately 20%).

Claims

1. Testing apparatus, which is a tyre testing apparatus, with a testing chamber (6), a pressure loading unit (20) for changing the pressure in the testing chamber and at least one measuring head (10) for measuring a measurement object arranged in the testing chamber (6) at different pressure values (20) produced by the pressure loading unit, characterized in that, for changing the pressure in the testing chamber, the pressure loading unit (20) changes the volume of the testing chamber (6) while excluding air from the surroundings, wherein the pressure loading unit (20) comprises a wall element (7) of the testing chamber which is movable with respect to the rest of the testing chamber structure (6) and by the movement of which the volume of the testing chamber can be changed.

2. Testing apparatus according to Claim 1, wherein the changing of the volume and / or pressure can preferably be controlled by way of the position of the movable wall (7) element.

3. Testing apparatus according to Claim 2, wherein the movable wall element (7) is in connection with the rest of the testing chamber structure (8) in a sealed manner by way of a flexible sealing element, in particular a bellows, and / or wherein the movable wall element (7) is formed by a flexible diaphragm which is in connection with the rest of the testing chamber structure in a sealed manner.

4. Testing apparatus according to Claim 2 or 3, wherein, when projected into a plane extending perpendicularly to its direction of movement, the movable wall element (7) has a surface area of at least 5% of the square of the cube root of the volume of the testing chamber (6), preferably at least 10%, more preferably at least 30%, and / or wherein, when projected into a plane extending perpendicularly to its direction of movement, the movable wall element (7) has a surface area of at least 0.05 m2, preferably of at least 0.2 m2, more preferably of at least 0.5 m2.

5. Testing apparatus according to one of the preceding claims, wherein the pressure loading unit (20) can change the volume of the testing chamber (6) by at least 0.5%, in particular by at least 1%, and / or wherein, by changing the volume of the testing chamber, the pressure loading unit (20) can change the pressure in the testing chamber (6) by at least 5 mbar, wherein the changing of the volume and / or pressure can preferably be controlled by way of the position of the movable element (7).

6. Testing apparatus according to one of the preceding claims, with a drive (9) by way of which the movable wall element (7) can be moved, wherein the testing apparatus preferably has a controller which controls the drive and the at least one measuring head (10) in such a way that the measurement object (5) is tested by the at least one measuring head (10) in at least one measurement cycle, in which the pressure in the pressure chamber (6) is changed by a movement of the movable wall element (7).

7. Testing apparatus according to Claim 6, wherein the drive (9) is a linear drive.

8. Testing apparatus according to one of the preceding claims, wherein the movable wall element (7) is arranged in the region of the ceiling of the testing chamber (6) and / or wherein movable wall elements (7) are provided on opposite sides of the testing chamber (6).

9. Testing apparatus according to one of the preceding claims, with an energy recovery unit for the energy recovery of the energy released by relieving the pressure in the testing chamber (6), wherein the energy stored in the energy recovery unit is preferably used for renewed pressure loading of the testing chamber (6).

10. Testing apparatus according to Claim 9, wherein the energy recovery unit comprises a force compensator, which produces a counter force to the compressive force which in the loaded state exerts a load on the pressure loading unit and in particular the movable element.

11. Testing apparatus according to Claim 9 or 10, wherein the energy recovery unit comprises at least one spring unit (31), in particular an air spring unit, and / or wherein the energy recovery unit comprises at least one linearly operating force element.

12. Testing apparatus according to one of the preceding claims, wherein a movable wall element (7) of the pressure loading unit (20) is in connection with at least one linearly operating force element, in particular a spring element (31), in such a way that the direction of the force of the force element changes with respect to a direction of movement of the movable wall element over the displacement range of the movable wall element.

13. Testing apparatus according to one of the preceding claims, wherein the movable wall element (7) of the pressure loading unit (20) is in connection with the testing chamber structure by way of at least two force elements, in particular in the form of spring elements (31), in such a way that the components of the forces that are generated by the force elements and act transversely to the direction of movement of the movable wall element (7) cancel one another out and the components that act in the direction of movement are cumulative.

14. Testing apparatus according to one of the preceding claims, wherein the measuring head (10) is an interferometric measuring head, in particular a shearography measuring head, and / or wherein the pressure loading unit generates a negative pressure in the testing chamber (6).

15. Method for testing a measurement object by a testing apparatus (6) according to one of the preceding claims, with the steps of: - introducing the measurement object (5) into the testing chamber (6) of the testing apparatus, and - measuring the measurement object (5) arranged in the testing chamber (6) at different pressure values, characterized in that the changing of the pressure in the testing chamber (6) is performed by changing the volume of the testing chamber while excluding air from the surroundings.