Measuring Device for Detecting an Operating Parameter of an Agricultural PTO Drive Shaft

Abstract

The present invention relates to a measuring device with a magnetic field sensor for detecting at least one operating parameter of an agricultural joint shaft for torque transmission between a power take-off shaft of a towing vehicle and a transmission of an agricultural appliance, which includes at least one journal cross, to the opposing journals of which a shaft body is connected, and a protective tube rotatably accommodating the shaft body therein, wherein the magnetic field sensor is adapted to measure a magnetic field emanating from the bare shaft body of the joint shaft.

Claims

1. A measuring device with a magnetic field sensor for detecting at least one operating parameter of an agricultural joint shaft for torque transmission between a power take-off shaft of a towing vehicle and a transmission of an agricultural appliance, which comprises at least one journal cross, to the opposing journals of which a shaft body is connected, and a protective tube rotatably accommodating the shaft body therein, wherein the magnetic field sensor is adapted to measure a magnetic field emanating from the bare shaft body of the joint shaft.

2. The measuring device according to claim 1, further comprising a closed sensor housing, which accommodates the magnetic field sensor and an energy source for the magnetic field sensor therein and is adapted for non-rotatable attachment to an outer or an inner side of the protective tube.

3. The measuring device according to claim 2, wherein the sensor housing has a concave inner surface which can be applied to the protective tube and is formed from at least one of curved surface sections or straight surface sections.

4. The measuring device of claim 3, wherein the sensor housing has, opposite the inner surface, a convex outer surface formed of at least one of curved surface sections or straight surface sections.

5. The measuring device according to claim 2, wherein the sensor housing is provided with a positioning journal on a side forming a contact surface for contact with the protective tube, which positioning journal engages in a bore of the protective tube.

6. The measuring device according to claim 2, further comprising at least one of an acceleration sensor or a temperature sensor provided in the sensor housing.

7. The measuring device according to claim 2, further comprising a processor provided in the sensor housing, which processes a sensor signal of at least one sensor to determine at least one operating parameter of the joint shaft.

8. The measuring device according to claim 7, further comprising an operating hours counter for the joint shaft, which is incremented as a function of the at least one operating parameter.

9. The measuring device according to claim 7, wherein the processor evaluates the sensor signal for detecting a movement of a working machine connectable to the joint shaft and increments an operating hours counter for the working machine as a function of a duration of the detected movement.

10. The measuring device according to claim 7, further comprising a transmitting device provided in the sensor housing and connected data-wise to the processor, which transmits at least one of the determined operating parameter(s) and a counter reading of the operating hours counter wirelessly to a receiver adapted for data processing.

11. The measuring device according to claim 8, further comprising means for outputting at least one of a warning signal and a maintenance signal triggered by reaching a predetermined counter reading of the operating hours counter.

12. The measuring device according to claim 7, further comprising a stand-by mode and an operating mode implemented as control logic on the processor, wherein the processor is arranged to switch from the stand-by mode to the operating mode in response to a sensor signal from one of the sensors.

13. An agricultural joint shaft for torque transmission between a power take-off shaft of a towing vehicle and a transmission of an agricultural appliance, with at least one journal cross, to the opposite journals of which a shaft body is connected, with a protective tube rotatably accommodating the shaft body, and with a measuring device comprising a magnetic field sensor for detecting at least one of an operation and an operating parameter of the agricultural joint shaft, wherein the measuring device is fastened in a rotationally fixed manner to the protective tube, and wherein the magnetic field sensor is adapted to measure a magnetic field change of a magnetic field emanating from the bare shaft body of the joint shaft.

14. The agricultural joint shaft according to claim 13, wherein the measuring device comprises a closed sensor housing, which accommodates the magnetic field sensor and an energy source for the magnetic field sensor therein, the sensor housing being dimensioned such that a protective funnel for the journal cross can be slipped over the sensor housing onto the protective tube.

15. The agricultural joint shaft according to claim 13, wherein the measuring device is configured to detect rotation of the protective tube.

16. The agricultural joint shaft according to claim 15, wherein the measuring device is configured to initiate at least one of a warning signal or an alarm in response to the detection of a rotation of the protective tube.

17. Method for detecting an operation of a work machine coupled to a commercial vehicle and connected to the commercial vehicle by an agricultural joint shaft for torque transmission between a power take-off shaft of the commercial vehicle and a transmission of the work machine, the agricultural joint shaft having at least one journal cross, to the opposing journals of which a shaft body is connected, and a protective tube rotatably accommodating the shaft body therein, wherein operation of the work machine is detected by evaluating a sensor signal of a magnetic field sensor measuring a magnetic field change of a magnetic field emanating from the bare shaft body of the agricultural joint shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Further details and advantages of the present invention will be apparent from the following description of embodiments in conjunction with the drawing. Therein:

[0036] FIG. 1 shows a side view of an agricultural joint shaft looking inside the protective tube by omitting the protective tube in the center of the Figure,

[0037] FIG. 2 shows a cross-sectional view of a joint shaft according to a first embodiment,

[0038] FIG. 3 shows a cross-sectional view of a joint shaft according to a second embodiment,

[0039] FIG. 4A shows a section of a perspective side view of the joint shaft according to the first embodiment,

[0040] FIG. 4B shows an enlarged view of detail I of FIG. 2,

[0041] FIG. 5 shows a diagram with measured acceleration and measured magnetic field over time and

[0042] FIG. 6 shows a diagram with process flow for operation recognition.

DESCRIPTION OF THE INVENTION

[0043] FIG. 1 shows a perspective side view of an agricultural joint shaft 1 with a first joint 2 and a second joint 3, which are connected to each other via a shaft body 4 that is adjustable in length. The shaft body 4 is made of steel and comprises an inner tube 5 connected to the first joint 2 and an outer tube 6 connected to the second joint 3. The inner tube 5 is accommodated in the outer tube 6 so as to be displaceable in the longitudinal direction L of the joint shaft 1. In order to prevent a loss of torque transmission due to mutual twisting of the inner tube 5 and the outer tube 6, the inner tube 5 and the outer tube 6 have a cross-section deviating from a circular shape. In this case, the inner tube 5 and the outer tube 6 have a so-called star profile (see FIG. 2) or a lemon profile (see FIG. 3).

[0044] In order to protect an operator, the agricultural joint shaft 1 comprises a joint shaft protection, which includes a protective tube 7 surrounding the shaft body 4 and two protective funnels 8, 9 covering the joints 2, 3. The joint shaft protection is generally made of ammonia-resistant plastic. The protective tube 7 consists of an outer protective tube 10 and an inner protective tube 11, wherein the inner protective tube 11 is accommodated in the outer protective tube 10 so as to be displaceable in the longitudinal direction L. The inner protective tube 11 is mounted in the outer protective tube 10. In order to prevent the joint shaft protection from rotating, a chain 12 is provided on the joint shaft protection, which can be attached to a towing vehicle or working appliance.

[0045] The joints 2, 3 are each configured as universal joints with a journal cross 13, 14, to the opposite journals of which a fork 15, 16 is connected. The opposing journals of the journal cross 13, 14, which are free in FIG. 1, are generally connected via a further (not shown) fork to a shaft body stub, which can be pushed onto a power take-off shaft stub of a power take-off shaft or a drive journal of a transmission of a driven machine for torque transmission.

[0046] According to the present invention, a measuring device is attached to the agricultural joint shaft 1. The shaft body may have a star profile or a lemon profile. It goes without saying that the measuring device according to the present invention can also be attached to other agricultural joint shafts and that the shaft body profiles mentioned are only given here as examples.

[0047] FIG. 2 illustrates a cross-sectional view of the joint shaft 1, in which a measuring device 44 for detecting at least one operating parameter of the agricultural joint shaft 1 is mounted on the protective tube 7 of the agricultural joint shaft 1. The measuring device 44 comprises a closed sensor housing 46, which encloses a magnetic field sensor 48, which is provided on a circuit board 50 with a processor 52. The circuit board 50 is supplied with electrical power from a battery 54 as a power source, wherein the battery 54 is also arranged in the closed sensor housing 46. The closed sensor housing 46 is made of plastic and encapsulates the components accommodated therein in all three spatial directions. The magnetic field sensor 48 is adapted to measure a magnetic field emanating from the bare shaft body 4 of the joint shaft 1.

[0048] The shaft body 4 of the joint shaft 1 has a star profile in cross-section, whereas the cross-section of the protective tube 7 is egg-shaped. The protective tube 7 has inwardly directed projections 58 that prevent twisting between the inner protective tube 5 and the outer protective tube 6. The sensor housing 46 has a positioning journal 60 centrally located on its underside, which engages a bore 62 on the protective tube 7 to secure the position of the sensor housing 46 on the outer circumference of the protective tube 7. The bore 62 is provided in the circumferential direction at the point where the egg-shaped cross-section has its apex.

[0049] The circle formed by dashed lines in FIG. 2 represents an installation space limit for the measuring device 44, which is derived from the inner diameter of the protective funnels 8, 9. The sensor housing 46 fits between the outer circumference of the protective tube 7 at its tip and the installation space limit. This allows the sensing device 44 to be located near either of the protective funnels 8, 9 without interfering with lubrication of the joints 2, 3. In the event of lubrication, the protective funnels 8, 9 can be pushed across the sensor housing 46 towards the axial center of the protective tube 7. The protective funnels 8, 9 may have a recess or flap at their narrower end through which the sensor housing 46 fits when the protective funnel 8, 9 is slid over it.

[0050] The processor 52 evaluates the signals from the magnetic field sensor 48 to determine at least one operating parameter of the joint shaft 1. The operating parameters include the detection of a rotation of the joint shaft 1 per se and, in particular, the rotational speed of the joint shaft 1. The rotational speed is generally determined by the joint shaft 1 generating periodic maxima and minima in the measured values of the magnetic field sensor 48 during a rotation. Since the geometry of the shaft body profile is known, the rotational speed can be determined from the period duration. An acceleration sensor 63 is also provided in the sensor housing 46. Its signals are used to determine a movement of an appliance connected to the towing vehicle. Noise and interference signals from the sensors are filtered out by logic implemented on the processor 52.

[0051] Further, a data memory (not shown) associated with the processor 52 for storing operating parameters and a transmitting device (not shown) for wirelessly transmitting data stored on the data memory are provided in the sensor housing 46. From the signals of the magnetic field sensor 48 and the acceleration sensor 63, the processor derives the operating hours of the joint shaft and the operating hours of the working appliance, which are recorded with operating hour counters implemented in the logic of the processor 52. The operating hours are stored and sent as operating parameters.

[0052] The logic of the processor 52 includes the previously described control for switching between the stand-by mode and the operating mode. A signal from the acceleration sensor 63 is used as a triggering signal for a switchover if it exceeds a predetermined threshold. The sensor housing 46 further has an externally visible LED (not shown) that lights up red as a warning signal as soon as one of the operating hour counters exceeds a predetermined threshold value.

[0053] FIG. 3 illustrates a second embodiment in which the previously described measuring device 44 is mounted on the protective tube 7 of the agricultural joint shaft 1 for detecting at least one operating parameter of the agricultural joint shaft 1, and the shaft body 4 of the joint shaft 1 has a lemon profile in cross-section, whereas the cross-section of the protective tube 7 is round. The extension of the protective tube 7 in the radial direction is smaller than that of the protective tube 7 of the first embodiment. Therefore, the contact surface at which the sensor housing 46 abuts the protective tube is further in the center of the sensor housing 46 in the cross-sectional view of the second embodiment than in the first embodiment.

[0054] The measuring device 44 is the same in both embodiments. The sensor housing 46 is configured in such a way that it can be applied to protective tubes of different sizes.

[0055] FIG. 4A shows a magnified view of the sensing device 44, and FIG. 4B illustrates that the sensor housing 46 has a convex inner surface 64 engageable with the outer periphery of the protective tube 7 and a concave outer surface 66 opposite the inner surface 64. Shown also are two screw tabs 68 projecting laterally from the sensor housing 46 and having a mounting hole for a screw to secure the sensor housing 46 to the protective tube 7.

[0056] FIG. 4B shows detail I of FIG. 2 in enlarged view, and it can be seen that the concave inner surface 64 is composed of two lateral straight surface sections 70 that would intersect if they were thought to be elongated, and a curved central surface section 72 that connects the two lateral straight surface sections 70. The concave outer surface 66 also includes two straight surface sections 74 that would intersect if they were thought to be elongated. However, the surface section connecting the straight surface sections 74 of the outer surface 66 is also formed as a straight surface section 76.

[0057] FIG. 4A shows the measuring device 44 in a perspective side view, illustrating that the sensor housing 46 is substantially round in a lateral circumferential direction. The circuit board 50 and the battery 54 are arranged one above the other.

[0058] It is understood that the present invention is not limited to said preferred spatial arrangement of the components in the sensor housing 46. For example: the circuit board 50 and the battery 54 may also be arranged side by side and/or the sensor housing 46 may be substantially rectangular in the circumferential direction; the sensor housing 46 can have a lid detachably connected to a main body of the sensor housing 46, so that the battery 54 can be replaced easily; the two screw tabs 68 can be aligned in a longitudinal direction of the protective tube 7; a rubber material can be provided between the protective tube 7 and a contact surface of the sensor housing 46; the positioning journal 60 and the bore 62 can be provided laterally on the underside of the sensor housing 46; at least two positioning journals 60 can be provided at locations corresponding to the location of the screw tabs 68, wherein the positioning journals can be designed to cooperate with the two screw tabs 68 by, for example, providing a female thread for the male thread of a screw; the position journal(s) 60 can have a shoe configured to butt against an inner surface of the protective tube and to install the position journal(s) 60 in the bore 62 with positive locking.

[0059] FIG. 5 shows an illustration with several graphs indicating an acceleration (in m/s.sup.2) and a magnetic field strength (in μT) measured by the measuring device over time (in s) on an agricultural joint shaft in the state of a working machine driven by the joint shaft. The processor uses the extremes of the graphs to evaluate the measurement data.

[0060] FIG. 6 illustrates in a diagram the process flow for detecting operation of an agricultural joint shaft and an appliance driven by the joint shaft. For simplicity, the agricultural joint shaft is referred to as “shaft” and the working machine as “application” in the diagram. The measuring device is delivered in sleep mode. If an acceleration exceeding a threshold value is registered by the acceleration sensor in sleep mode, the measuring device switches to operating mode.

[0061] In the operating mode, at least the acceleration sensor and the magnetic field sensor are in the activated state and the processor evaluates the measurement signals of the sensors continuously, for example in a time increment of one second. According to the evaluation whether the shaft or the application are in operation, an operating hours counter for the application and an operating hours counter for the shaft are incremented. The counter readings can be sent simultaneously (see “Advertisement data”) or with a time delay to a receiver, which can be a mobile terminal and/or provided in the towing vehicle, for example.

LIST OF REFERENCE SIGNS

[0062] 1 agricultural joint shaft [0063] 2 first joint [0064] 3 second joint [0065] 4 shaft body [0066] 5 inner tube [0067] 6 outer tube [0068] 7 protective tube [0069] 8, 9 protective funnel [0070] 10 outer protective tube [0071] 11 inner protective tube [0072] 12 chain [0073] 13, 14 journal cross [0074] 15, 16 fork [0075] 44 measuring device [0076] 46 sensor housing [0077] 48 magnetic field sensor [0078] 50 circuit board [0079] 52 processor [0080] 54 battery [0081] 58 projection [0082] 60 positioning journal [0083] 62 bore [0084] 63 acceleration sensor [0085] 64 inner surface [0086] 66 outer surface [0087] 68 screw tab [0088] 70 lateral straight surface section of the inner surface [0089] 72 curved surface section of the inner surface [0090] 74 lateral straight surface section of the inner surface [0091] 76 straight central surface section of the inner surface