TEST SYSTEM AND METHOD FOR EXAMINING A HOLLOW BODY

Abstract

A test system for examining a hollow body, in particular a cylinder bore in an engine block, comprises a measuring apparatus comprising an elongate body and a plurality of sensors which are connected to the body and are set up to carry out a distance measurement. The test system also comprises electronic control means which are set up to move the measuring apparatus into a hollow body to be examined and to determine an internal diameter of the hollow body on the basis of distance measurement data from the sensors. In order to examine hollow bodies of different diameters, at least some of the sensors are in the form of movable sensors which can be moved relative to the elongate body of the measuring apparatus. The electronic control means are also set up to select a measuring position of the movable sensors relative to the elongate body on the basis of a hollow body to be examined. A calibration station is provided and the electronic control means are set up to carry out a calibration process for the movable sensors. A corresponding method is also disclosed.

Claims

1. Test system for examining a hollow body (1), in particular a cylinder bore (2) in an engine block (1), with a measuring device (10) comprising an elongate body (12) and several sensors (15, 16) which are connected to the body (12) and adapted to carry out a distance measurement, electronic control means which are adapted to move the measuring device (10) into a hollow body (1) to be examined and to determine an internal diameter of the hollow body (1) on the basis of distance measurement data of the sensors (15, 16), characterized in that for the examination of hollow bodies (1) of different diameters at least a part of the sensors (15, 16) are designed as movable sensors (15, 16) which are optical sensors (15, 16) and movable relative to the elongate body (12) of the measuring device (10) at least in the radial direction, in that depending on a hollow body (1) to be examined the electronic control means are adapted to select a measuring position of the movable optical sensors (15, 16) relative to the elongate body (12), in that a calibrating station (30) is provided and in that the electronic control means are adapted to carry out a calibration process for the movable sensors (15, 16) on the calibrating station (30), wherein for a calibration measurement the optical sensors (15, 16) are moved to a reference measuring position relative to the elongate body (12).

2. Test system according to claim 1, characterized in that in the calibration process the measuring device (10) is moved to the calibrating station (30), the movable sensors (15, 16) are moved to a specific reference measuring position relative to the elongate body (12), with the movable sensors (15, 16) in the reference measuring position a reference measurement is carried out, with which distances to the calibrating station (30) are measured, a relation between previously known dimensions of the calibrating station (30) and measurement data of the reference measurement is ascertained and stored and in that the electronic control means are adapted to take the ascertained relation into account in the determination of an internal diameter of a hollow body (1) to be examined on the basis of the distance measurement data of the sensors (15, 16).

3. Test system according to claim 1 or 2, characterized in that the electronic control means are adapted to carry out the calibration process at least every time a next hollow body (1) with a measuring position different to a previous hollow body (1) is to be examined.

4. Test system according to any one of claims 1 to 3, characterized in that the calibrating station (30) comprises at least one reference ring (31, 32, 33), into which the measuring device (10) is moved.

5. Test system according to claim 4, characterized in that the calibrating station (30) comprises several reference rings (31, 32, 33) which differ in their respective internal diameter.

6. Test system according to claim 5, characterized in that the several reference rings (31, 32, 33) are arranged concentrically on top of each other.

7. Test system according to claim 5 or 6, characterized in that the electronic control means are adapted to select one of the reference rings (31, 32, 33) depending on the expected internal diameter of the hollow body (1) to be examined.

8. Test system according to any one of claims 1 to 7, characterized in that the reference measuring position of the movable sensors (15, 16) is the same as a measuring position, in which a hollow body (1) is examined after the calibration process has been carried out.

9. Test system according to any one of claims 1 to 8, characterized in that the movable sensors (15, 16) are adjustable in the radial direction with respect to the elongate body (12).

10. Test system according to any one of claims 1 to 9, characterized in that the movable sensors (15, 16) comprise at least three sensors (15, 16), the measuring direction of which is offset to each other in the azimuthal direction.

11. Test system according to any one of claims 1 to 10, characterized in that the electronic control means, by taking an expected internal diameter of the hollow body (1) to be examined into account, are adapted to set a measuring position, to which the movable sensors (15, 16) are moved for a distance measurement.

12. Coating system for coating an inner wall (3) of a hollow body (1), in particular a running surface (3) of a cylinder bore (2) in an engine block (1), with at least one rotatable coating lance, by which a metal plasma jet for coating the inner wall (3) can be generated, and a test system according to any one of claims 1 to 11.

13. Coating system according to claim 12, characterized in that the electronic control means are adapted to ascertain an internal diameter of the hollow body (1) by means of the measuring device (10), to then apply a coating with the coating lance onto an inner wall of the hollow body (1), to subsequently ascertain an internal diameter of the hollow body (1) now coated by means of the measuring device (10), to calculate a thickness of the coating by comparing the internal diameters ascertained before and after application of the coating.

14. Method for examining a hollow body (1), in particular a cylinder bore (2) in an engine block (1), wherein a measuring device (10) is provided which comprises an elongate body (12) and several sensors (15, 16) which are connected to the body (12) and adapted to carry out a distance measurement, wherein the measuring device (10) is moved into a hollow body (1) to be examined, carries out a distance measurement to an inner wall (3) of the hollow body (1) there and on the basis of distance measurement data of the sensors (15, 16) an internal diameter of the hollow body (1) is determined, characterized in that for the examination of hollow bodies (1) of different diameters at least a part of the sensors (15, 16) are designed as movable sensors (15, 16) which are optical sensors (15, 16) and movable relative to the elongate body (12) of the measuring device (10) at least in the radial direction, in that depending on a hollow body (1) to be examined a measuring position of the movable sensors (15, 16) relative to the elongate body (12) is selected and in that a calibration process for the movable sensors (15, 16) is carried out on a calibrating station (30), wherein for a calibration measurement the optical sensors (15, 16) are moved to a reference measuring position relative to the elongate body (12).

15. Method according to claim 14, characterized in that for testing of an inner wall of the hollow body (1) the movable sensors (15, 16) are moved away from the elongate body (12) when the measuring device (10) has moved into the hollow body (1) to be examined, and in that the movable sensors (15, 16) are retracted in the direction of the elongate body (12) while the measuring device (10) is being moved into a hollow body (1) to be examined or moved out of a hollow body (1) to be examined.

Description

[0052] Further advantages and features of the invention are described hereinafter with reference to the accompanying schematic Figure.

[0053] FIG. 1 shows a schematic illustration of an embodiment of a test system according to the invention and of a hollow body to be examined.

[0054] In FIG. 1 an embodiment of a test system 100 according to the invention and of a hollow body 1 to be examined is shown schematically.

[0055] The test system 100 comprises a measuring device 10 for examining a hollow body 1, a holding device, not depicted here, for the hollow body 1 currently to be examined and a calibrating station 30 for the measuring device 10.

[0056] A hollow body 1 to be examined or tested can be an engine block with several cylinder bores 2 for example. Testing involves the properties of the cylinder bores 2, especially the diameter of the respective cylinder bore 2.

[0057] For this purpose, a measuring device 10 is employed that comprises an elongate body 12 and sensors 15, 16, 17 connected thereto.

[0058] Due to the elongate body 12 the measuring device 10 can be moved into the cylinder bores 2. In the Figure this movement is illustrated by the double arrow 11 in the axial direction of the cylinder bore 2. Expediently, for this purpose a diameter of the elongate body 12 is smaller than the diameters of the cylinder bores 2, while the length of the elongate body 12 can be greater.

[0059] The sensors 15, 16, 17 or components thereof can be connected indirectly or directly to the elongate body 12. For instance some of the sensors or all of them can have optical fibers which are guided on the elongate body and via which measuring light can be emitted and/or received.

[0060] Sensor 17 can be designed for taking a panoramic picture, for which it can receive light from a 360°-range. To this end, a mirror or a prism inclined with respect to the longitudinal axis of the elongate body 12 can be used that is rotationally symmetrical to the longitudinal axis. In this way, light from a 360°-range around the longitudinal axis can be transmitted towards a camera or another type of optical receiver of the sensor 17.

[0061] With such a sensor 17 properties of an inner wall 3 of a hollow cylinder can be tested, in particular the roughness or material properties that have an effect on a paint of the inner wall 3.

[0062] To measure a diameter of the cylinder bore 2 use is made of the sensors 15, 16 in particular. At least three, by preference precisely three sensors 15, 16 of the same type are present, two of which are shown in the Figure for clarified illustration. The sensors 15, 16 each measure a distance to the inner wall 3 of the cylinder bore 2. Knowing the dimensions of the measuring device 10 the diameter can be calculated from the measured spaces/distances.

[0063] If the measuring device 10 is moved into the cylinder bore 2 precisely on the longitudinal axis thereof, one sensor 15 with one distance measurement would already be sufficient to ascertain the diameter precisely. In practice, however, deviations of the measuring device 10 from the longitudinal axis of the cylinder bore 2 cannot be avoided. Nevertheless, the diameter can be determined with a high level of accuracy if three sensors 15, 16 are present that measure the distance in different directions.

[0064] A preferred application of ascertaining the diameter by means of the measuring device 10 resides in determining the thickness of a coating of the inner wall 3 of a hollow cylinder 2. To this end, a diameter is measured before and after application of a coating. The difference of these diameter values results in the thickness of the applied coating. For conclusive results of a relatively thin layer the distance measurements have to be implemented with the greatest accuracy.

[0065] The sensors currently available for this have a strongly limited measuring range so that the sensors 15, 16 have to be moved to a distance to the inner wall 3 that lies within their measuring range. Since the diameters of different cylinder bores 2 can vary (for example according to the engine model) and in order to prevent collisions of the sensors 15, 16 with the hollow body 1 the sensors 15, 16 are designed in a movable manner. They can be extended transversely to the longitudinal axis of the elongate body 12, i.e. in the direction of the double arrow 14 in FIG. 1, until their distance to the inner wall 3 lies within their measuring range. The position of the movable sensors 15, 16, in which a distance measurement to the inner wall 3 is effected, is in the present case referred to as measuring position that relates to the position relative to the elongate body 12.

[0066] In order that a diameter can be ascertained precisely by way of such distance measurements the measuring position of the sensors 15, 16 must be known as precisely as possible. If an actual measuring position deviates from an assumed measuring position this has a detrimental effect on the accuracy of the diameter value ascertained.

[0067] To solve this problem a calibrating station 30 is employed. On this, a distance measurement is carried out with the sensors 15, 16, in which case the dimensions of the calibrating station are already known and thus the result of the distance measurement can be compared with a previously known value. In particular, the calibrating station 30 can have one or several cylindrical openings with a diameter known in each case. On the basis of the distance measurements of the sensors 15, 16 a diameter is calculated that is compared with the known diameter. The relation of these values is used as a calibration, i.e. it is used in the calculation of a diameter from distance measurements made on examined hollow cylinders 2.

[0068] The position, into which the sensors 15, 16 are moved relative to the elongate body 12 for the calibration process, is in the present case referred to as reference measuring position. By preference, the reference measuring position is the same as the measuring position used for the testing of a hollow cylinder 2 directly succeeding the calibration process or directly preceding the calibration process.

[0069] Therefore, it is desirable that the calibrating station 30 has several cylindrical openings of different diameters, from which in each case one can be selected for the calibration process, the diameter of which comes closest to the diameter of the cylinder bore tested afterwards or beforehand.

[0070] The calibrating station 30 can in particular have several rings 31, 32, 33 that each have a different diameter, i.e. internal diameter. By the use of separate rings 31, 32, 33 a ring can be added or exchanged if hollow bodies 1 of different dimensions are to be tested henceforth.

[0071] For a better overview a section through the rings 31 to 33 is shown in FIG. 1. Expediently, use is not made of half rings but closed rings 31 to 33. Likewise, merely for the sake of a better overview the cylinder bore 2 in the hollow body 1 is shown in cut-away view, and is in fact a cylinder bore 2 that is closed over the entire shell surface.

[0072] The rings 31 to 33 and related holding means of the calibrating station 30 can be designed such that the rings 31 to 33 can be held concentrically on top of each other. As a result, a movement of the measuring device 10 to the desired ring 31, 32 or 33 can take place easily.

[0073] Advantageously, through the calibration process there is the achievement that the relative position of the movable sensors 15, 16 relative to the elongate body 12 of the measuring device 10 can be determined and/or taken into account. This is of particular advantage if a specific measuring position can be assumed in a substantially reproducible manner while precise knowledge of this measuring position is not available without calibration.

[0074] Thus, the invention provides a test system and a method, with which an internal diameter of a hollow body, in particular a cylinder bore in an engine block, can be ascertained precisely and easily. It is also possible to determine internal diameters of different sizes with a high level of accuracy.