(51) Int.Cl.⁶:

(19) Federal Republic of Germany G 01 M 13/02

[emblem] G 01 L 3/00

German Patent and Trademark Office

(12) Patent

(10) DE 198 05 756 C1

(21) Application number: 198 05 756.3-51

(22) Filing date: February 13, 1998

(43) Disclosure date: -

(45) Publication date

of patent grant: October 14, 1999

Opposition may be lodged within three months following publication of grant.

(73) Patent holder: ZF Friedrichshafen AG, 88046 Friedrichshafen, DE (72) Inventor: Joachim, Franz-Josef, 88131 Bodolz, DE; Kurz, Norbert, 88693 Deggenhausertal, DE (56) Documents taken into consideration to evaluate patentability: DE 43 25 403 C2 DE 29 48 517 C2 DE 23 26 582 C2 DE-PS 3 48 708 DE 196 21 185 A1 DE 43 28 637 A1 DE 42 10 990 A1 DE 33 11 618 A1 DE 30 47 334 A1 US 41 88 821 EP 00 21 223 A1

LANGENBECK, Konrad; BENTHAKE, Heinrich: “Gear Stressing Test Rigs for Research and Development”, in VDI-Z 115, 1973, No. 2 February., pp. 115 - 121. HENNIGS, G.: “A Gear Stress Test Rig with Adjustable Loading Program”. in Maschinenbautechnik 19, 1970, issue 5, pp. 259 - 262; antriebstechnik 22 (1983) no. 10, pp. 32, 34, 36 and 38; antriebstechnik 11 (1972) no. 9, pp. 332 - 336;

(54) Device for Testing A Thrust Collar

(51) The invention relates to a device for testing a thrust collar (25, 26) for gear pairs, which exhibit teeth that extend helically in relation to their axes (13, 14).

It is proposed that the thrust collar (25, 26) shall be provided with a helical tooth system and/or a bevel gear tooth system on one test gear pair (17); that a drive motor (1) drives the test gear pair (17) by means of a straight toothed drive gear pair (9) and essentially axially parallel shaftings (7, 8) with a tensioning device (16); that the stress moment of the tensioning device (16) generates counter-acting axial forces on the thrust collar (25, 26) by means of the teeth of the test gear pair (17); and that a shaft (6) of a shafting with the associated test gear (19) is moveably mounted in the housing (12, 20) in the direction (15) of the corresponding axial force.

[see figure]

DE 198 05 756 C1

Government Printing Office 08.99 902 141/259/7A 16

Description

The invention relates to a device for testing a thrust collar, according to the preamble of claim 1.

During the transmission of a torque, meshing gear wheels, which exhibit teeth that extend helically in relation to their rotational axes - for example, helically toothed gears, bevel gears, crown gears or the like, generate an axial force, which must be braced in order to guarantee the mating of the gear wheels. Usually the axial forces are braced against the housing by means of the axial mounting bearing by way of the shafts, on which the gear wheels are fastened. They must be designed relatively large as a function of the torque to be transmitted. Furthermore, in the case of so-called idler gears, which are mounted rotatably on a shaft, the axial bearings must also be provided between the gear wheel and the shaft.

Another possibility of bracing the axial forces lies in the fact that the meshing gear wheels, which generate counter-acting axial forces, are mutually braced in the axial direction by means of thrust collars. The thrust collars are disk-shaped bearing elements, which are disposed on the front side of the meshing gear wheels in that they are molded on the gear wheels or are fixed in a suitable way as a separate component. A disk of the thrust collar, which is fastened to the one gear wheel, overlaps radially a counter-disk on the other gear wheel so that both disks slide with conical thrust faces on each other.

In order to test power-transmitting components and aggregates - for example gear wheels, gear units, clutches, shafts, etc., there exist two types of test rigs ("antriebstechnik" 11, 1972, no. 9, pages 332 - 336; "VDI-Z" 115, 1973, no. 2, pages 115 - 121; "antriebstechnik" 22, 1983, no. 10, pages 32, 34, 36 and 38) and, in particular, so-called brake test rigs, where the drive power runs from one drive motor over a test specimen to a brake system, or so-called stress test rigs, where the test power circulates as the reactive power in a stress circuit, in which the test specimen is enclosed, and only the resulting power losses are covered by a drive motor - usually an electric motor. In the second case the load on the test specimen is only a moment, composed of the stress moment and the moments, which are to be generated by the drive motor and which result from the power loss and the moment of inertia. If the test specimen is a test gear pair with a helical tooth system, then the axial forces, generated in the test specimen, are absorbed by the axial bearings of the shafts, on which the test gears are fastened.

However, the stress moment can also be provided so as to be defined by means of a tensioning device. However, it is also known (DE 43 25 403 C2) to change the stress moment during the test in order to control or regulate. To this end there is a microprocessor-controlled, electric control unit - for example, a motor or generator -, which engages with the stress circuit by means of a high ratio superimposed gear unit - for example, in the form of a strain wave gear
(“harmonic drive”) unit - and generates an angle of flexure between the input and the output. As an alternative, a hydraulic stress moment can also be used.

Similar devices are known from a plethora of other publications. Thus, for example, the DE 29 48 517 C2 relates to a device and a method for measuring immediately the power loss of gear units. In this case at least two identical gear units to be tested are driven in a closed power cycle; and the total power loss of the power cycle is determined by measuring the drive speed and the driving moment.

The DE-PS 3 48 708 discloses a device for testing gear units. This device makes it possible to use a sliding clutch, which acts like a brake, to set an arbitrary load on the gear unit.

Another gear test rig is disclosed in the DE 43 28 537 A1. It exhibits, in addition to a drive motor, another motor, which is connected to the output shaft of the gear unit by means of a clutch. The additional motor can be used as both a drive motor and as a decelerating motor.

The DE 33 11 618 A1 describes a device for determining the quality of gear units, in particular of spiral bevel gears and rotational speed epicyclic gear units.

The US 4 188 821 describes a device for sensing and measuring the torque output of a gear unit. In this case a measurement adapter is disposed between the shaft bearing and the bearing mounting housing.

The DE 23 26 582 C2 relates to a torque measuring device in a gear speed reducer, which exhibits strain gauges for measuring the pressure forces.

A method and a device for measuring the torque in order to monitor the tool with the aid of contactless position sensors are disclosed in the DE 196 21 185 A1.

The DE 42 10 990 A1 describes a configuration for measuring the torque in a gear unit. In this case at least one distance sensor is directed towards a plane surface of at least one gear wheel and is connected to an evaluation device.

The DE 30 47 334 A1 discloses a thrust collar gear unit having at least two helically toothed gear wheels and having thrust collars, which are provided on both sides. In this case the size ratios between the thrust collars and the tip diameters are important.

The EP 0 021 223 A1 discloses a thrust collar gear unit having at least two meshing gear wheels, of which the one gear wheel is provided with a thrust collar and the other gear wheel is provided with an axial pressure element.

The technical journal Maschinenbautechnik (volume 19 (1970) issue 5, pages 259 to 262) discloses a gear stress test rig with an adjustable loading program.

The object of the invention is to test a thrust collar with very little complexity. The invention achieves this object with the features disclosed in claim 1. Other embodiments are disclosed in the dependent claims.

According to the invention, the thrust collar is provided on a test gear pair having a helical tooth system and/or a bevel gear tooth system. The test gear pair is assigned to two shaftings, which are coupled not only by means of the test gear pair but also by mean of a straight toothed drive gear pair and can be braced against each other by means of a tensioning device. In order to load the thrust collar with axial forces, which are generated from the toothing systems of the test gear pair (said toothing systems extending helically in relation to their axes), a shaft of a shafting with the associated test gear is mounted movably in the housing in the direction of the corresponding axial force. The axial forces, acting on the thrust collar, are a function of the stress moment of the tensioning device and the angle that the teeth exhibit in relation to the direction of the rotational axes. Since the drive gear pair is straight toothed, it does not contribute to the axial force.

The important measured variables for the testing are detected electronically and evaluated in a microprocessor unit to form controlled variables, which adjust the drive motor, the tensioning device and other auxiliary units, to a desired operating state. These measured and controlled variables include the speed of the drive motor, a variable of the tensioning device that is proportional to the stress moment, the lubricating oil temperature, a torque of a shaft between a drive gear and a test gear, which act on the drive motor and the tensioning device as well as the auxiliary units, the time period and an additional axial force. The measured variables are sensed with suitable sensors and fed over signal lines to the microprocessor unit.

Since the axial force can be increased only by a larger stress moment that puts a significant load on the test gears, it is advantageous to apply by mechanical, hydraulic, pneumatic or electric means an additional axial force, acting on the thrust collar, to the moveably mounted shaft. This axial force stresses not only the test gears, but also braces itself against the axial bearings of the parallel shafting by means of the thrust collar. Thus, the thrust collar can be loaded with significantly higher axial forces than would have been practical and possible with just the stressing force alone without destroying the test gears. In addition, the test gears can be simultaneously differentially loaded and tested at least independently of the thrust washers in that the stress moment and the additional axial force are suitably compatibilized. This can done by the microprocessor unit with a specified program.

The additional axial force can be generated in a simple way by means of a mechanical loading device, which, on the one hand, is braced against a housing -- for example, the drive housing, and, on the other hand, acts on the moveable shaft by way of an axial bearing.

Other advantages are disclosed in the following description of the drawings. The drawings show one embodiment of the invention. The description and the claims include a number of features in combination. The person skilled in the art will examine the features, if desired, even individually and combine them logically so as to form other combinations.

Figure 1 is a schematic drawing of the configuration of the device according to the invention.

Figure 2 is a longitudinal sectional view of an additional mechanical loading device; and

Figure 3 is a sectional view along the line III-III in Figure 2.

A drive motor 1 - usually an electric motor - drives with its motor shaft 2 via an articulated shaft 3 a shafting 7, which is formed by two partial shafts 4 and 5 as well as a tensioning device 16 that is disposed between both partial shafts. A straight toothed spur gear 10 is mounted on the partial shaft 4. Said straight toothed spur gear meshes with another spur gear 11, which sits stationarily on a second shaft 6 and forms with the first spur gear 10 a drive gear pair 9. A test gear 19 is mounted on the other end of the shaft 6. This test gear forms together with a test gear 18 on the partial shaft 5 a test gear pair 17. The second shaft 6 represents a second shafting 8, which is coupled to the first shafting 7 by means of the drive gear pair 9 and the test gear pair 17. Both shaftings 7, 8 can be braced against each other by means of the tensioning device 16. The stress moment of the tensioning device 16 stresses the test gears 18 and 19 in the circumferential direction so that an axial force, acting in the direction of the arrow 15, acts in the drive train 8, whereas an axial force acts in the opposite direction in the drive train 7. The counter-acting axial forces are braced against each other by means of a thrust collar 25, 26. In this case a washer 25, which is fastened to the test gear 18, covers radially in certain places a counter-washer 26 on the test gear 19 and rests against said counter-washer. The size and the direction of the counter-acting axial forces depend on the size and the direction of the stress moment that matches in essence a moment for covering the losses and for overcoming the moments of inertia.

The shaftings 7 and 8 are mounted in bearing points 21 and 22 of a drive housing 12 and in bearing points 23 and 24 of a test gear housing 20. The housings 12 and 20 are mounted together with the drive motor 1 on a machine foundation (not shown in detail). They can also be configured as one piece and can carry a drive motor 1, which is mounted by means of a flange. Whereas the first drive train 7 is mounted in the bearing points 21 and 23 both radially and axially in both directions, the shaft 6 of the drive train 8 is mounted in the bearing points in such a manner that it can be moved axially in the direction of the axial force, indicated by an arrow 15, and, thus, can be braced against the washer 25 of the thrust collar by means of the counter-washer 26.

Important measured variables 58, which include the speed n of the drive motor 1, a torque T of the shaft 6, the lubricating oil temperature t in the test gear housing 20, and an additional axial force F, are detected by sensors - in particular, a speed sensor 29, a torque measuring hub 30, a pressure sensor 31, a temperature sensor 32 and a tractive force measuring device 53 - and are fed over signal lines 28 to a microprocessor unit 27. This microprocessor unit evaluates the measured variables 58 and forms controlled variables 59, for example for the speed n of the drive motor 1, for a variable p of the tensioning device 16 that is proportional to the stress moment, and for auxiliary units for influencing the oil temperature t. If the tensioning device 16 is a hydraulic actuator, then the hydraulic pressure may serve as the proportional variable p.

In order to put a higher load on the thrust collar 25, 26 than that which matches the stress moment of the tensioning device 16, there is an additional loading device 33, which generates an axial force F that acts axially on the shaft 6 in the direction of the arrow 15. The loading device 33 can exert, in principle, a mechanical, electrical, pneumatic, or hydraulic effect and can also be actuated by the microprocessor unit 27. Such a simple mechanical design is shown in Figure 2.

The drive-sided end of the shaft 6, on which the spur gear 11 sits, is mounted in a bearing cover 34 by means of a radial bearing 39. Adjacent to the bearing cover 34 is a housing flange 35, in which a pressure ring 36 can be slid in the axial direction and is braced via an axial bearing 38 against a shaft collar 40 of the shaft 6. The pressure ring 36 is in relation to the housing flange 35 by means of a sealing ring 37 and in relation to the elongated shaft 6 by means of a shaft seal 42, which rests against a bushing 41, which is mounted stationarily on the shaft 6. This prevents the shaft 6 from being abraded in this region.

A cantilever beam 49 strains the pressure ring 36 by means of two cylinder pins 51 and 52, which are aligned radially and diametrically to the axis 14 of the shaft 6 and which are embedded in depressions of the pressure ring 36 and the cantilever beam 49. Furthermore, they run perpendicular to a central connecting plane of two threaded rods 43, 44, which hold the cantilever beam 49 at the drive housing 12 and brace against the axial bearing 38 by means of screw connections 45 and 46. The connecting plane corresponds to the drawing plane in Figure 2. The cylinder pins 51, 52 cause the axial force to be introduced centrally so that the pressure ring 36 cannot rotate and that there is some margin for tilting the cantilever beam 49.

In order to be able to generate a uniform and easily adjustable axial force by way of the threaded rods 43, 44, there is a spring 50 in the form of a cup spring assembly between the screw connection 46 and the cantilever beam 49. This cup spring assembly is braced against the cantilever beam 49 by way of a spherical bearing 48. The spherical bearing 48 provides together with an additional spherical bearing 47 between the screw connection 45 of the threaded rod 43 and the cantilever beam 49 that the center of the threaded rods 43 and 44 is put under tension. The axial force is measured by a traction force measuring device 53, which is arranged in the force flow of the threaded rod 44. Since the tractive force measuring device 53 engages with the cantilever beam 49 at a longer distance from the threaded rod 43, which is arranged diametrically to the axis 14 than the axial force, the measured force in proportion to the lever arms is less than the axial force that is generated. The signal for the measured force is fed over a signal line 28 to the microprocessor unit 27 and modulated by a carrier frequency amplifier, evaluated and displayed digitally.

The elongation of the shaft 6 runs through the cantilever beam 49. The shaft carries a torque transmitter 54, by means of which the torque measuring signal of the torque measuring hub 30 is picked off and is fed over a signal line 28 to the microprocessor 27. In order to cool adequately well the axial bearing 38 and to provide sufficient lubricating oil, there is a lubricating oil connection 55 in the immediate vicinity.

List of Reference Numerals

1 drive motor

2 motor shaft

3 articulated shaft

4 first partial shaft

5 second partial shaft

6 second shaft

7 first shafting

8 second shafting

9 drive gear pair

10 first spur gear

11 second spur gear

12 drive housing

13 axis

14 axis

15 arrow

16 tensioning device

17 test gear pair

18 first test gear

19 second test gear

20 test gear housing

21 bearing point

22 bearing point

23 bearing point

24 bearing point

25 test washer

26 counter-washer

27 microprocessor unit

28 signal line

29 speed sensor

30 torque measuring hub

31 pressure sensor

32 temperature sensor

33 loading device

34 bearing cover

35 housing flange

36 pressure ring

37 sealing ring

38 axial bearing

39 radial bearing

40 shaft collar

41 bushing

42 shaft seal

43 threaded rod

44 threaded rod

45 screw connection

46 screw connection

47 spherical bearing

48 spherical bearing

49 cantilever beam

50 spring

51 cylinder pin

52 cylinder pin

53 tractive force measuring device

54 torque transmitter

55 lubricating oil connection

58 measured variable

59 controlled variable

Patent Claims

1. Device for testing a thrust collar (25, 26) for gear pairs, which exhibit teeth that run helically to their axes (13, 14), characterized in that the thrust collar (25, 26) is provided on a test gear pair (17) having a helical tooth system and/or a bevel gear tooth system; that a drive motor (1) drives the test gear pair (17) by means of a straight toothed drive gear pair (9) and essentially axially parallel shaftings (7, 8) with a tensioning device (16); that the stress moment of the tensioning device (16) generates counter-acting axial forces on the thrust collar (25, 26) by means of the teeth of the test gear pair (17); and that a shaft (6) of a shafting with the associated test gear (19) is moveably mounted in the housing (12, 20) in the direction (15) of the corresponding axial force.

2. Device, as claimed in claim 1, characterized in that at least one of the following measured variables (58) is sensed electronically and evaluated in a microprocessor unit (27) to form at least one corresponding controlled variable (58): a speed (n) of the drive motor (1), a variable (p) of the tensioning device (16) that is proportional to the stress moment, the lubricating oil temperature (t), a torque (T) of a shaft (6) between a drive gear (11) and a test gear (19), the time and an additional axial force (F).

3. Device, as claimed in claim 1 or 2, characterized in that an additional axial force (F), acting on the thrust collar (25, 26), is applied to the moveably mounted shaft (6) by mechanical, hydraulic, pneumatic or electric means.

4. Device, as claimed in claim 3, characterized by an additional mechanical loading device (33) between the drive housing (12) and the moveable shaft (6), said loading device acting on the shaft (6) by means of an axial bearing (38).

5. Device, as claimed in claim 4, characterized in that the loading device (33) has a pressure ring (36), which is prestressed by a cantilever beam (49) and by means of two threaded rods (43, 44), which are arranged diametrically to the axis (14) and which strains the axial bearing (38).

6. Device, as claimed in claim 5, characterized in that the pressure ring (36) is braced against the cantilever beam (49) by means of two cylinder pins (51, 52), which are aligned radially and diametrically to the axis (14) and are situated diagonally to a central connecting plane of the threaded rods (43, 44).

7. Device, as claimed in any one of the claims 5 or 6, characterized in that the threaded rods (43, 44) are braced against the cantilever beam (49) by way of spherical bearings (47, 48); and that at least one screw connection (45, 46) of a threaded rod (43, 44) is braced against a spherical bearing (47, 38) by means of a spring (50).

8. Device, as claimed in any one of the claims 5 to 7, characterized in that the threaded rods (43, 44) are arranged so as to be symmetrical to the axis (14) and that a threaded rod (44) engages with a tractive force measuring device (53).

9. Device, as claimed in any one of the claims 5 to 8, characterized in that the moveable shaft (6) is mounted on the one torque measuring hub (30), is passed through the cantilever beam (49) and carries on its free end a torque transmitter (54) in order to transmit the torque measuring signal.

10. Device, as claimed in any one of the claims 5 to 9, characterized by a lubricating oil connection (55) in the region of the axial bearing (38).

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3 pages of drawings

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