TECHNICAL FIELD

The present disclosure relates to articulated joints in mining machines. Specifically, the present disclosure relates to a sensor assembly for determining a rotational relative position of a first object in a mining machine with respect to a second object in a mining machine. The first object and the second object may for example be a front frame and rear frame respectively of a chassis of a mining machine. Other uses of the sensor assembly are also feasible.

BACKGROUND

An articulated mining machine comprises a joint between a first frame and a second frame of the vehicle. Upon steering and maneuvering the mining machine, the first frame rotates relatively the second frame about a rotational axis defined by the joint. When implementing autonomous or self-driving operation of the mining machine, information indicating the relative position of the first frame relatively the second frame is useful. Autonomous and self-driving operation of mining machines is especially advantageous for electric work machines, such as electric mining machines, which may be fully automated. It is also useful to monitor the position of other articulated joints in mining machines, such as the tilt position of the dump box of a mine truck.

Joints of mining machines are often heavily loaded and thus tend to wear, leading to gradually increasing play between parts. A sensor attached between parts moving relatively each other at rotation about a joint thus have to cope with the play, and readings output by the sensor may be affected by the play as wear progresses. Further, the play may lead to excessive forces on the sensor, leading to sensor failure.

Accordingly, there is a need to provide for a robust and accurate sensor assembly for determining a rotational relative position of a first object of a mining machine with respect to a second object of a mining machine, said second object being rotatably attached to the first object for relative rotation about a first rotational axis. SUMMARY

An object of the present disclosure is to provide a robust and accurate sensor assembly for determining a rotational relative position of a first object of a mining machine with respect to a second object of a mining machine, said second object being rotatably attached to the first object for relative rotation about a first rotational axis.

According to a first aspect of the present disclosure, this object is achieved by a sensor assembly as defined in appended claim 1 , with alternative embodiments defined in its dependent claims.

The sensor assembly comprises a first mount attachable to the first object, and a second mount attachable to the second object. The sensor assembly further comprises an angular position sensor comprising a first member and a second member rotatably attached to the first member for relative rotation about a second rotational axis. The angular position sensor is configured to provide an electronic indication indicating a rotational relative position of the second member with respect to the first member about the second rotational axis. The first member is attached to the first mount and the first mount is attachable to the first object such that the second rotational axis is aligned with the first rotational axis. The sensor assembly further comprises an arm connecting the second member of the angular position sensor to the second mount. The arm is attached to the second member of the angular position sensor such that the arm is able to rotate the second member about the second rotational axis upon rotation of the arm about the second rotational axis.

A typical use case for the sensor assembly is to determine the rotational position of an articulated joint of a mining machine, wherein the first object is a first frame of the mining machine, and the second object is a second frame of the mining machine rotatably attached to the first frame for relative rotation about a first rotational axis. In this use example, the first frame and the second frame respectively also comprise, by definition, any portion of an articulated joint rotatably attaching the first frame to the second frame. Specifically, the fixed central shaft of the embodiment of fig. 1 is fixedly attached to the rest of the first frame, effectively forming part of the first frame.

The present sensor assembly may thus be used by mounting the first mount to the first frame and the second mount to the second frame as shown in the figures. Preferably, the first mount should be mounted to the first frame such that the second rotational axis is aligned with the first rotational axis defined by the rotatable attachment between the first and second frames. When the first frame is rotated relatively the second frame about the first rotational axis, the second mount is rotated relatively the first object along an approximately circular path about the first and second rotational axes. Accordingly, the arm connecting the second mount to the second member of the angular position sensor, rotates about the first and second rotational axes, wherein the indication provided by the angular position sensor is directly correlated to the angle between the first frame and the second frame of the mining machine.

By providing the angular position sensor on a first mount attached to the first object, the angular position sensor moves together with the first object thereby keeping its alignment. The provision of the arm connecting the angular position sensor to the second object via the second mount enables a relatively large radial offset between the second rotational axis and the second mount, making the system less sensitive to vibrations since a relatively large movement of the second mount is associated with a relatively small change in the rotary angle of the angular position sensor, thereby providing for a more robust position detection. Also, the use of the arm enables great flexibility as to where to connect the sensor assembly to the second object, wherein the sensor assembly can easily be adapted to use with different types of objects.

The arm may be connected to the second member of the angular position sensor via an intermediate member rotatably supported on the first mount for rotation about the second rotational axis.

The intermediate member is rotatably supported on the first mount and thus isolates the angular position sensor from forces from the arm, except for torque around the second rotational axis. This protects the angular position sensor from excessive forces, prolongs the lifetime of the angular position sensor and further increases precision of the movement of the second member of the angular position sensor by guiding the arm. As the rotatable attachment between the first object and the second object is worn, radial and axial play increases between the first object and the second object, which means that the second rotational axis may become increasingly radially offset from the first rotational axis. Such radial offset increases a tendency of the second mount to move radially towards or radially away from the first mount upon relative rotation between the first object and the second object, which in turn gives rise to forces on the arm. The arm may be telescopic or otherwise configured to accommodate movement of the second mount towards the second rotational axis and away from the second rotational axis.

By making the arm telescopic or configured to accommodate movement of the second mount towards the second rotational axis and away from the second rotational axis, the second mount is able to move towards and away the first mount substantially without causing excessive force acting radially on the intermediate member or the second member of the angular position sensor with respect to the second rotational axis. Also, installation of the arm is easier, since the adjustable length of the arm enables easier alignment of the first mount and of the second mount to pre-positioned fastening means, such as holes or guides, on the first object and the second object. Also, the self-adjusting length of the arm is especially advantageous upon wear of the rotatable attachment between the first object and the second object leading to offset between the first rotational axis and the second rotational axis.

The arm may comprise a plurality of sections engaging each other telescopically.

The telescopic engagement between the sections provides a simple and robust means of accommodating changes in distance between the first mount and the second mount.

The arm may be provided with a resilient dust protection means, such as a boot, covering at least a portion of the plurality of sections.

The resilient dust protection means seals to the first mount and to the arm thereby forming a sealed inner space around at least a portion of the plurality of sections.

The first mount may comprise a base plate for attachment to the first object, and a cap or housing attached to the base plate by one or more mechanical connectors such that an inner space is formed between the base plate and the cap. The angular position sensor is attached to the cap/housing within said inner space of the first mount.

The arm may be connected to the second mount by a joint configured to enable relative rotation of the arm with respect to the second mount. The joint connecting the arm to the second mount may comprise a ball joint, a hinge joint, a swivel joint or an elastic joint comprising a piece of elastic material joining the arm to the second mount.

The arm may be connected to the second member of the angular position sensor by a hinge joint or an elastic joint comprising a piece of elastic material joining the arm to the second member.

An aspect of the present disclosure relates to a mining machine comprising a sensor assembly as described above with reference to claim 1 with alternative embodiments defined in its dependent claims.

The mining machine comprises a first object rotatably attached to a second object for rotation about a first rotational axis. Also, the mining machine comprises a sensor assembly for determining a rotational relative position of the first object with respect to the second object, such as the sensor assembly described above.

The sensor assembly comprises a first mount attached to the first object, a second mount attached to the second object, an angular position sensor comprising a first member and a second member rotatably attached to the first object for relative rotation about a second rotational axis. The angular position sensor is configured to provide an electronic indication indicating a rotational relative position of the second member with respect to the first member about the second rotational axis. The first member is attached to the first mount and the first mount is attached to the first object such that the second rotational axis is aligned with the first rotational axis. Also, the sensor assembly comprises an arm connecting the second member of the angular position sensor to the second mount. The arm is attached to the second member of the angular position sensor via a first joint configured to enable the arm to rotate the second member about the second rotational axis upon rotation of the arm about the second rotational axis.

The first object may comprise a central shaft defining the first rotational axis, wherein the second object comprises a bearing rotatably supporting the second object on the central shaft for rotation about the first rotational axis, and wherein the first mount is attached to an end portion of the central shaft. The mining machine may comprise a first frame rotatably joined to a second frame for steering of the mining machine, wherein the first frame is the first object and wherein second frame is the second object.

The above aspects, accompanying claims, and/or examples disclosed herein above and later below may be suitably combined with each other as would be apparent to anyone of ordinary skill in the art.

Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the disclosure as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a side view of a mining machine in the form of an electric battery operated loader for use in mining operations.

Fig. 2 shows a top view of the loader also shown in fig. 1 when turning.

Fig. 3 shows a partial side view of a first frame and a second frame of the loader shown in figs. 1-2 with a sensor assembly mounted for determining relative rotation of the first frame with respect to the second frame about the articulated joint.

Fig. 4 shows an enlarged partial view of region A indicated in fig. 3.

Fig. 5 shows the sensor assembly also shown in fig. 4, however mounted to the loader via a bracket rather than directly to a fixed shaft of the articulated joint.

Figs. 6-8 show various views of an embodiment of the sensor assembly when not yet fitted to a joint of a mining machine.

DETAILED DESCRIPTION

Aspects set forth below represent information to enable those skilled in the art to practice the disclosure. As mentioned above, an object of the present disclosure is to provide a robust and accurate sensor assembly for determining a rotational relative position of a first object of a mining machine with respect to a second object of a mining machine, said second object being rotatably attached to the first object for relative rotation about a first rotational axis. Examples of mining machines are LHD:s (loader hauler dumpers), concrete spraying machines, drilling rigs and/or bolting rigs, or other types of vehicles configured to perform work operations in a mining environment.

According to an aspect of the present disclosure, this object is achieved by a sensor assembly as described below.

Figs. 1-2 show an articulated mining machine 14. As shown in figs. 2-3, a chassis of the mining machine 14 comprises a first frame 2 in a back portion of the mining machine 14, rotatably joined to a first frame 3 in a front portion of the mining machine 14 by an articulated joint defining a first rotational axis A1. Fig. 4 shows enlarged region A of fig. 3 showing an upper portion of the articulated joint. The articulated joint also comprises a similar lower portion as shown in the bottom portion of fig. 3. Accordingly, only the upper portion will be described here. In alternative embodiments, the articulated joint may comprise only one such portion, or more than two such portions.

As shown in fig. 4, the first frame 2 comprises a cylindrical shaft 17 along the first rotational axis A1. The shaft is fitted between an upper mount 15 and a lower mount 16, both mounts 15, 16 forming part of the first frame 2. Further, the shaft 17 is fixed to the upper plate 15 and the lower plate 16 such that the shaft 17 cannot rotate relatively the rest of the first frame 2. The second frame 3 comprises a connection plate 18 provided with a bearing 19 adapted to fit on the shaft 17 such that the second frame 3 is rotatable about the first rotational axis A1. The bearing 19 is held in place by an upper fixation plate 20 and a lower fixation plate 21 , both fixation plates 20, 21 being attached to the connection plate 18 by bolts.

The upper and lower mounts 15, 16 of the first frame comprise a respective removable member 15a, 16a attachable to a respective fixed portion 15b, 16b using bolts (not shown). Each respective removable member 15a, 16a and each corresponding fixed portion 15b, 16b are shaped to clamp the shaft 17 to the first frame 2 when the removable members 16b are mounted. Hence, after the bearing 19 and the shaft 17 have been fitted to the second frame 3, the shaft 17 is clamped to the first frame 2 by attachment of the removable members 15a, 16a to the fixed portions 15b, 16b, of the first frame 2.

In other embodiments, the joint between the first frame 2 and the second frame 3 may alternatively have any other suitable design.

In order to be able to determine the relative rotational position of the first frame 2 with respect to the second frame 3 about the first rotational axis A1, the sensor assembly 1 is mounted to the first frame 2 and to the second frame 3, i.e. to objects which are rotatable relatively each other about the first longitudinal axis A1.

It should be understood that the sensor assembly is also applicable to any other joint between objects of the mining machine 14 which are rotatable relatively each other about a longitudinal axis, for determining relative rotational positions of the objects about the longitudinal axis. For example, the sensor assembly could be used for monitoring movement of a joint between a chassis frame of a loader and an arm carrying a bucket of the loader, and for monitoring movement of a joint between the bucket and the arm carrying the bucket.

In the present exemplary embodiment, the sensor assembly 1 comprises a first mount 4 attachable to the first frame 2, and a second mount 5 attachable to the second frame 3. The sensor assembly 1 further comprises an angular position sensor 6 comprising a first member 7 and a second member 8 rotatably attached to the first member 7 for relative rotation about a second rotational axis A2. The angular position sensor 6 is configured to provide an electronic indication indicating a rotational relative position of the second member 8 with respect to the first member 7 about the second rotational axis A2. The first member 7 is attached to the first mount 4 and the first mount 4 is attached to the first object 2 such that the second rotational axis A2 is aligned with the first rotational axis A1.

The sensor assembly 1 further comprises an arm 9 connecting the second member 8 of the angular position sensor 6 to the second mount 5. The arm 9 is fixed to the second member 8 of the angular position sensor 6 such that the arm is able to rotate the second member 8 about the second rotational axis A2 upon rotation of the arm 9 about the second rotational axis A2. In other embodiments, the attachment of the arm 9 to the second member 8 may have any other suitable configuration as long as the arm is able to apply a torque to the second member 8 about the first rotational axis A1. For example, the arm 9 may be attached to the second member 8 by splines allowing the arm 9to move relatively the second member 8 along the first rotational axis A1.

As shown in fig. 8, the arm 9 is connected to the second member 8 of the angular position sensor 6 via an intermediate member 10 rotatably supported on the first mount 4 for rotation about the second rotational axis A2. In other embodiments, the intermediate member may alternatively be omitted and the arm directly supported on the second member 8 of the angular position sensor 6. However, the provision of the intermediate member 10 supported by the first mount 4 isolates lateral forces on the arm, i.e. forces not parallel to the rotational axis A1, such that such lateral forces do not load the second member 8.

The arm 9 comprises a plurality of sections 9a, 9b engaging each other telescopically and thus accommodates movement of the second mount 5 towards the second rotational axis A2 and away from the second rotational axis A2. In other embodiments, any other suitable design of the arm could be used instead allowing for said accommodation of relative movements changing the distance between the second mount 5 and the second rotational axis A2. For example, the arm 9 could comprise a rigid rod pivotally connected to the second mount 5, wherein the rod runs freely through an opening of the first mount 4, said opening of the first mount being 4 shaped to prevent rotational play between the rod and the first mount 4 about the first longitudinal axis A1.

The arm 9 is provided with a resilient dust protection means 11 in form of a boot covering a portion of the plurality of sections 9a, 9b. The resilient dust protection means 10 seals to the first mount 4 and to the arm 9 thereby forming a sealed inner space around at least a portion of the plurality of sections 9a, 9b. In other embodiment, the dust protection means 11 may alternatively be omitted.

The first mount 4 comprises a base plate 12 attached to the first frame 2 using bolts. The first mount 4 further comprises a cap or housing 13 attached to the base plate 12 by bolts such that an inner space is formed between the base plate 12 and the cap 13. The angular position sensor 6 is attached to the cap 13 within said inner space of the first mount 4 but may in other embodiments be attached to some other member or portion of the first mount 4 as long as the first member 7 of the angular position sensor is fixed to the first mount 5, and thus fixed to the first object 2. The arm 9 is connected to the second mount 5 by a joint configured to enable relative rotation of the arm 9 with respect to the second mount 5 about a rotational axis perpendicular to the first rotational axis A1. In this embodiment, the joint connecting the arm 9 to the second mount 5 is a hinge joint but may alternatively in other embodiments comprise an elastic joint comprising a piece of elastic material joining the arm 9 to the second mount 5.

As shown in fig. 8, the arm 9 is connected to the second member 8 of the angular position sensor 6 by a hinge joint 22. In other embodiments any other suitable joint could be used instead of the hinge joint, such as an elastic joint comprising a piece of elastic material joining the arm 9 to the second member 8.

The sensor assembly may also be used to determine be mounted to the mining machine at manufacturing of the mining machine, or the sensor assembly provided as a separate device for mounting anywhere on a mining machine for determining a rotational position of another joint.

The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises," "comprising," "includes," and/or "including" when used herein specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure. Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the inventive concepts being set forth in the following claims.

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