EP1084388A1

EP1084388A1 - Magnetic clamping for in-process verification

Info

Publication number: EP1084388A1
Application number: EP99955322A
Authority: EP
Inventors: James C. Juranitch; Lawrence C. Theisz; Robert D. Olschefski
Original assignee: Veri-Tek Inc; Veri Tek Inc
Current assignee: Veri-Tek Inc; Veri Tek Inc
Priority date: 1998-06-01
Filing date: 1999-05-25
Publication date: 2001-03-21
Also published as: JP2002517714A; AU4313099A; MXPA00011903A; CA2333769A1; WO1999063318A1

Abstract

An arrangement for testing engines for vehicles and other drive train assemblies employs magnetic clamping to achieve fixation of the rotatory drive train assembly to a drive arrangement. When the rotatory drive train assembly is a vehicle engine, there is a need to affix a measurement head that contains sensors to the engine. This too is effected by magnetic clamping. A robotic transport device or overhead crane conveys the engine to a testing station where a human operator guides the drive arrangement into position on the engine. When the engine and the drive arrangement are appropriately aligned the operator will actuate a switch that activates electromagnets to effect the fixation of the engine to the drive arrangement. A human operator also guides the measurement head to the engine, and it is magnetically clamped thereto. When it is desired to release the engine from the drive arrangement, a deactivation switch that is manipulable by the operator discontinues the electrical energy to the electromagnet, except for a degaussing signal that utilizes the electromagnet to dissipate residual magnetism in the engine. A similar degaussing process is employed upon disengagement of the measurement head.

Description

Magnetic Clamping for In-Process Verification

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION

This invention relates generally to arrangements that effect in-process verification in manufacturing environments, and more particularly, to a verification process that employs magnetic clamping to effect engagement between the drive train component under test and the test drive arrangement and sensor head.

DESCRIPTION OF THE RELATED ART

When it is desired to attach production testing equipment for the purpose of verifying quality or functionality of a subassembly, or a finished product, at assembly line speeds, it is often difficult to find a mechanical method that functions reliably. In-process verification is a philosophy applied in modern production areas where each stage of a subassembly is tested for quality and function before progressing to the next stage of assembly. Upon detection of a fault, the in-process verification process philosophy would require that the subassembly should be disassembled, reassembled, and retested before proceeding to the production process. This process allows the production facility to build products of high quality that do not require final test or repair. Process control is also improved in response to the information obtained at each in-process verification stage or station. In order to implement the required testing systems at each stage, or station, of assembly, both mechanical and electrical drives and measurement systems must be clamped or rigidly attached to the production subassembly. In the present art, mechanical arms, pawls, and toggles are employed to effect such clamping. Such mechanical clamping arrangements, however, pose difficulties due to the lack of common clamping points on modern products that typically have been designed in response to size and weight considerations. The problem is made more difficult by the fact that modern production lines have been optimized to run numerous different models of similar products on the same production lines. Oftentimes, no station change-over time is available between batches of different models and assemblies. A conventional testing system for a vehicle engine is shown in Figs. 1 and 2. Fig. 1 is a partially schematic plan representation of a conventional clamping arrangement 10 for testing an engine 11. In this known arrangement, engine 11 is a diesel engine. Pawls 13 secure engine 1 1 to a drive arrangement 15 that uses an electric motor 16 to provided rotatory mechanical energy to engine 11 for testing purposes. The drive arrangement is guided into engagement with engine 11 by a human operator (not shown in this figure).

Fig. 2 is a partially schematic side representation of the conventional clamping arrangement of Fig. 1. Elements of structure that have previously been described are similarly designated. This figure shows that in the convention clamping arrangement, a plurality of pawls 13 are employed to effect the fixation of engine 11 to drive arrangement 15. As can be seen from this figure, pawls 13 are deployed at different lengths, as required by the particular structure of the system under test.

The conventional arrangement of Figs. 1 and 2 is additionally provided with measurement heads 26 that contain sensors (not specifically designated) that monitor predetermined operating characteristics and parameters of engine 1 1 while its crankshaft

(not shown) is being rotated by the drive arrangement. Figs. 1 and 2 additionally show that the measurement heads are attached in a conventional manner to the engine by arms 28 and toggles 29. The measurement head is guided onto engine 11 by a human operator 20 using handles 22 and 23. All of the structural elements that are employed in the affixation of the drive arrangement and the measurement head to the engine must be configured to the particular engine under test. It is difficult and time consuming to remove and replace the pawls, arms, and toggles with coupling devices that are configured specifically for each engine model on the assembly line.

It is, therefore, an object of this invention to provide an in-process verification system that is readily adaptable to different models of similar products on the same production lines.

It is another object of this invention to provide an in-process verification system that facilitates affixation of multiple drives and measurement systems to a product being manufactured in a simple and economical manner. SUMMARY OF THE INVENTION

The foregoing and other objects are achieved by this invention which provides, in a first apparatus aspect thereof, an arrangement for testing a rotatory drive train assembly for a motor vehicle. The rotatory drive train assembly is of the type that has a rotatory input. In accordance with the invention, a drive arrangement having a rotatory output provides mechanical rotatory energy to the rotatory drive train assembly. A first magnet clamps the rotatory drive train assembly and the drive arrangement to each other,. In this manner, the rotatory input of the rotatory drive train assembly is arranged to receive the rotatory mechanical energy from the drive arrangement. A sensor measures a predetermined operating characteristic of the rotatory drive train assembly as it is operated by the drive arrangement. A second magnet clamps the sensor to the rotatory drive train assembly.

In one embodiment of the invention, the first and second magnets are configured as respective electromagnets. There is additionally provided a source of electrical energy for providing electrical energy to the first and second electromagnets. In a specific embodiment, the source of electrical energy is arranged to provide electrical energy having a varying amplitude, whereby the first and second magnets operate in response thereto to demagnetize the rotatory drive train assembly. In this manner, residual magnetism in the rotatory drive train assembly is dissipated. Preferably, the amplitude of the electrical energy varies alternatingly, and in accordance, with a predetermined degaussing process.

In a further embodiment of the invention, the rotatory drive train assembly that is subjected to testing is a vehicle engine. The drive arrangement is configured to provide the rotatory mechanical energy to the crank shaft of the vehicle engine. There is additionally provided a measurement head that supports the sensor. In an illustrative embodiment of the invention, the measurement head is configured as a temporary testing head for the engine. Thus, a variety of engine conditions and characteristics can be tested. Generally, an engine that is desired to be tested is transported to the testing area by a robotic or overhead crane arrangement. A typical robotic arrangement will support the vehicle engine to be tested in a manner that permits a human operator to guide the drive arrangement onto the engine. A pair of handles generally is provided on a frame attached to the drive arrangement whereby the human operator can effect such guidance of the drive arrangement. Activation of the electromagnets that effect the fixation of the vehicle engine to the drive arrangement, and the measurement head to the vehicle engine, is effected by an activation switch. In a specific illustrative embodiment of the invention, the activation switch applies the engagement electrical energy to the first electromagnet, whereupon the rotatory drive train assembly is engaged with drive arrangement. The activation switch may be located, in some embodiments of the invention, on one of the handles to be gripped by the human operator. On the other handle may be provided a deactivation switch that discontinues the engagement electrical energy to the first electromagnet, thereby releasing the rotatory drive train assembly from the drive arrangement. In a highly advantageous embodiment of the invention, the deactivation switch also causes a degaussing signal to be applied to the first electromagnet for dissipating a residual magnetism in the rotatory drive train assembly. The degaussing signal constitutes electrical energy that varies in amplitude over time in accordance with a predetermined degaussing process. In accordance with a further apparatus aspect of the invention, an arrangement is provided for testing a rotatory drive train assembly for a motor vehicle. The rotatory drive train assembly is of the type having a rotatory input. In accordance with this further aspect of the invention, a drive arrangement is provided having a rotatory output for providing a rotatory mechanical energy to the rotatory drive train assembly. A first magnet is employed to clamp the rotatory drive train assembly and the drive arrangement to each other. In this manner, the rotatory input of the rotatory drive train assembly receives the mechanical energy from the drive arrangement. Further in accordance with this aspect of the invention, a manual guidance arrangement enables a human operator to guide the drive arrangement to the vicinity of the rotatory drive train assembly. An electrical energy supply is provided for supplying an electrical energy, the energy therefrom being controlled by a controller that controls the delivery of the electrical energy to the first magnet means.

In one embodiment of this further aspect of the invention, the controller includes an activation switch for applying the engagement electrical energy to the first magnet thereby urging the rotatory drive train assembly into engagement with the drive arrangement. A deactivation switch is provided for discontinuing the engagement electrical energy to the first magnet means, thereby releasing the rotatory drive train assembly from the drive arrangement. In a further embodiment, the deactivation switch is arranged to apply a degaussing signal to the first electromagnet for dissipating a residual magnetism in the rotatory drive train assembly.

In accordance with a further embodiment of the invention, there is provided a sensor for measuring a predetermined operating characteristic of the rotatory drive train assembly in response to the drive arrangement. Additionally, there is provided a second magnet for clamping the sensor to the rotatory drive train assembly. A further activation switch applies the engagement electrical energy to the second magnet so as to urge the sensor into engagement with the rotatory drive train assembly.

In accordance with a method aspect of the invention, there is provided a method of testing a rotatory drive train assembly, the method includes the steps of: guiding a rotatory mechanical drive to the vicinity of the rotatory drive train assembly; applying an electrical energy to an electromagnet whereby the rotatory drive train assembly becomes magnetically attached to the rotatory mechanical drive; activating the rotatory mechanical drive to apply a mechanical drive to the rotatory drive train assembly for a predetermined testing period of time; discontinuing the electrical energy to the electromagnet whereby the rotatory drive train assembly becomes removable from the rotatory mechanical drive; and applying a degaussing process to the rotatory drive train assembly.

In a further embodiment of this method aspect of the invention, the step of applying a degaussing process includes the step of conducting an electrical degaussing signal to the electromagnet for dissipating a residual magnetism in the rotatory drive train assembly.

In a further embodiment, there are further provided the steps of: guiding a sensor assembly into the vicinity of the rotatory drive train assembly; applying an electrical energy to a further electromagnet whereby the sensor assembly becomes magnetically attached to the rotatory drive train assembly; and after performing the step of activating the rotatory mechanical drive to apply a mechanical drive to the rotatory drive train assembly for a predetermined testing period of time, performing the further steps of: discontinuing the electrical energy to the further electromagnet whereby the sensor assembly becomes removable from the rotatory drive train assembly; and applying a further degaussing process to the rotatory drive train assembly.

BRIEF DESCRIPTION OF THE DRAWING

Comprehension of the invention is facilitated by reading the following detailed description, in conjunction with the annexed drawing, in which:

Fig. 1 is a partially schematic plan representation of a conventional clamping arrangement for testing an engine, using toggle latches;

Fig. 2 is a partially schematic side representation of the conventional clamping arrangement of Fig. 1; Fig. 3 is a partially schematic plan representation of a latching arrangement constructed in accordance with the principles of the invention; and

Fig. 4 is a partially schematic side representation of the clamping arrangement of Fig. 3.

DETAILED DESCRIPTION OF THE INVENTION Fig. 3 is a partially schematic plan representation of a latching arrangement constructed in accordance with the principles of the invention. As shown in this figure, in-process testing arrangement 40 has, as a unit under test, a diesel engine 42 (illustrated schematically) that is shown to be coupled to a drive arrangement 44 having an electric motor 45 associated therewith. Motor 45, in this embodiment, is a powerful, relatively slow speed motor that defines over 8000 angular positions, and drives the crankshaft (not shown) of engine 42 to rotate, in this embodiment, at up to about 15 rpm. The drive arrangement is guided to engage with the engine by a human operator 46 who controls the location and orientation of drive arrangement 44 via one or more handles, such as handle 49. Handle 49, for example, has disposed thereon a switch 48 that, in this specific illustrative embodiment of the invention, will cause conduction of electrical energy from an electrical source 55 to one or more electromagnets 56. In a practical embodiment of the invention, electromagnets 56 require a relatively low amount of electrical power to effect a magnetic attraction between the drive arrangement and the engine of several hundred pounds, illustratively 800 to over 1000 pounds. In one embodiment of the invention, the electromagnets maintain the clamping action upon being supplied less than 10 amps at a nominal 12 volts. After clamping of the drive arrangement is effected, a controller (not shown) will cause a drive engager 58 to be urged outward of the drive arrangement and to couple with a crankshaft flange 57 of the engine. The crankshaft flange has a timing pin therein (not shown) with which the drive engager communicates to deliver mechanical rotation at low speed, illustratively about 15 rpm. The figure additionally shows a further human operator 47 who will guide the placement of a measurement head 60, the functionality of which will be described hereinbelow with respect to Fig. 4. Fig. 3 shows operator 47 guiding the measurement head via handles 50 and 51.

Fig. 4 is a partially schematic side representation of the clamping arrangement of Fig. 3. Elements of structure that bear analogous correspondence to those already discussed are similarly designated. This figure shows that engine 42 has disposed thereon a measurement head 60 that has installed thereon, in this specific illustrative embodiment of the invention, a plurality of sensors (not specifically designated). The measurement head is attached to the engine by at least one electromagnet 61, which also is controlled by a switch (not specifically identified) on one or both of handles 50 and 51. In operation, the measurement head will, for example, determine the maximum height of piston travel within a cylinder, in relation to a machined surface where the engine heads would be installed. Such a determination employs, for example, linear voltage differential transformer (LVDT) devices (not shown). In addition, the measurement head will assist in determining the top dead center ("TDC") position of a predetermined piston in relation to the angular position of the timing pin of the crankshaft In these tests, the linear displacement of the sensors detected by the LVDT devices is correlated graphically against angular position of the crankshaft

Other tests that can be run simultaneously with those of the measurement head include, for example, checking for the integrity and operability of the oil delivery system within the engine Pressurized air is applied to the oil distribution system, and back pressure therein is monitored as the engine is rotated These pressure measurements are graphically correlated to crankshaft angular position, and are useful to determine whether bearings or other components are outside of predetermined tolerances A still further test that can be performed by the testing apparatus of the present invention relates to the engine cam (not shown) A probe (not shown) extends from the measurement head and enters through a push rod aperture to communicate with the cam As the engine is rotated, the linear displacement of the rod as it follows the rotating cam is measured using a LVDT device (not shown), thereby enabling correlation of the angle of the cam lobe with the angular position of the crankshaft (not shown) of the engine

In this illustrative embodiment, after completion of the test, it is desired to release the engine from the electromagnets and to eliminate any residual magnetism on the engine as a result of the magnetic attachment by the electromagnets Such residual magnetism is dissipated by applying a degaussing signal (not shown) to the electro- magnets after the electromagnetic affixation has been discontinued The degaussing signal, which in some embodiments of the invention is obtained from electrical source 55, is formed of alternating current that has a varying amplitude In a practical embodiment of the invention, the degaussing signal is a decaying alternating electric signal that has a frequency of about 15 FIz and decays to substantially zero amplitude in about 2 to 3 seconds This degaussing function is performed on both sets of electromagnets, i.e., those that couple the drive assembly to the engine under test, and those that couple the measurement head to the engine under test.

Although the invention has been described in terms of specific embodiments and applications, persons skilled in the art can, in light of this teaching, generate additional embodiments without exceeding the scope or departing from the spirit of the claimed invention. Accordingly, it is to be understood that the drawing and description in this disclosure are proffered to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

Claims

WHAT IS CLAIMED IS:

1. An arrangement for testing a rotatory drive train assembly for a motor vehicle, the rotatory drive train assembly having a rotatory input, the arrangement comprising: a drive arrangement having a rotatory output for providing a rotatory energy to the rotatory drive train assembly; first magnet means for clamping the rotatory drive train assembly and the drive arrangement to each other, whereby the rotatory input of the rotatory drive train assembly is arranged to receive the rotatory energy from said drive arrangement; a sensor for measuring a predetermined operating characteristic of the rotatory drive train assembly in response to said drive arrangement; and second magnet means for clamping said sensor to the rotatory drive train assembly.

2. The arrangement of claim 1, wherein said first and second magnet means are first and second electromagnets, respectively, and there is further provided electrical source means for providing electrical energy to said first and second electromagnets.

3. The arrangement of claim 2, wherein said electrical source means is arranged to provide alternating electrical energy having a varying amplitude, whereby said first and second electromagnets operate to demagnetize the rotatory drive train assembly.

4. The arrangement of claim 3 , wherein the amplitude of the electrical energy provided by said electrical source means varies alternatingly.

5. The arrangement of claim 4, wherein the alternating electrical energy is arranged to vary in amplitude in accordance with a predetermined degaussing process.

6. The arrangement of claim 1 , wherein the rotatory drive train assembly is a vehicle engine, and said drive arrangement is configured to provide the rotatory energy to a crankshaft of the vehicle engine.

7. The arrangement of claim 6, wherein there is further provided a measurement head for supporting said sensor, said measurement head being configured as a temporary testing arrangement.

8. The arrangement of claim 2, wherein there is further provided a handle arrangement for facilitating guiding of said measurement head by a human operator into predetermined orientation with respect to said drive arrangement.

9. The arrangement of claim 8, wherein there is further provided switch means on said handle arrangement for controlling the application of electrical energy to said first and second electromagnets.

10. The arrangement of claim 9, wherein said switch means comprises: an activation switch for applying an engagement electrical energy to said first electromagnet for urging the rotatory drive train assembly into engagement with said drive arrangement; and a deactivation switch for discontinuing the engagement electrical energy to said first electromagnet for releasing the rotatory drive train assembly from said drive arrangement

11. The arrangement of claim 10, wherein said deactivation switch is arranged to apply a degaussing signal to said first electromagnet for dissipating a residual magnetism in the rotatory drive train assembly.

12. The arrangement of claim 1 1, wherein the degaussing signal constitutes electrical energy that varies in amplitude over time in accordance with a predetermined degaussing process.

13. An arrangement for testing a rotatory drive train assembly for a motor vehicle, the rotatory drive train assembly having a rotatory input, the arrangement comprising: a drive arrangement having a rotatory output for providing a rotatory energy to the rotatory drive train assembly; first magnet means for clamping the rotatory drive train assembly and the drive arrangement to each other, whereby the rotatory input of the rotatory drive train assembly is arranged to receive the rotatory energy from said drive arrangement; manual guidance means for enabling a human operator to guide said drive arrangement to the vicinity of the rotatory drive train assembly; an electrical energy supply for supplying an electrical energy; and control means for controlling the delivery of the electrical energy to said first magnet means.

14. The arrangement of claim 13, wherein said control means comprises: an activation switch for applying the engagement electrical energy to said first magnet means for urging the rotatory drive train assembly into engagement with said drive arrangement; and a deactivation switch for discontinuing the engagement electrical energy to said first magnet means for releasing the rotatory drive train assembly from said drive arrangement

15. The arrangement of claim 14, wherein said deactivation switch is arranged to apply a degaussing signal to said first electromagnet for dissipating a residual magnetism in the rotatory drive train assembly.

16. The arrangement of claim 13, wherein there is further provided: a sensor for measuring a predetermined operating characteristic of the rotatory drive train assembly in response to said drive arrangement; and second magnet means for clamping said sensor to the rotatory drive train assembly.

17. The arrangement of claim 16, wherein there is further provided a further activation switch for applying the engagement electrical energy to said second magnet means for urging said sensor into engagement with the rotatory drive train assembly.

18. A method of testing a rotatory drive train assembly, the method comprising the steps of: guiding a rotatory mechanical drive into the vicinity of the rotatory drive train assembly; applying an electrical energy to an electromagnet whereby the rotatory drive train assembly becomes magnetically attached to the rotatory mechanical drive; activating the rotatory mechanical drive to apply a mechanical drive to the rotatory drive train assembly for a predetermined testing period of time; discontinuing the electrical energy to the electromagnet whereby the rotatory drive train assembly becomes removable from the rotatory mechanical drive; and applying a degaussing process to the rotatory drive train assembly.

19. The method of claim 18, wherein said step of applying a degaussing process comprises the step of conducting an electrical degaussing signal to the electromagnet for dissipating a residual magnetism in the rotatory drive train assembly.

20. The method of claim 19, wherein there are further provided the steps of: guiding a sensor assembly into the vicinity of the rotatory drive train assembly; applying an electrical energy to a further electromagnet whereby the sensor assembly becomes magnetically attached to the rotatory drive train assembly; after performing said step of activating the rotatory mechanical drive to apply a mechanical drive to the rotatory drive train assembly for a predetermined testing period of time, performing the further steps of: discontinuing the electrical energy to the further electromagnet whereby the sensor assembly becomes removable from the rotatory drive train assembly; and applying a further degaussing process to the rotatory drive train assembly.