Sensor Device with Conversion of the Horizontal Angular Movement of a Boom of an Earth-Moving Machine

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The present invention belongs to the technical field of guiding earth-moving machinery, for example mechanical excavators used for excavation, digging, earth-moving, backfilling, etc. In particular, the invention applies to hydraulic excavators with an arm that is offset at the boom foot or at a portion of the boom.

More particularly, the invention concerns an angular movement conversion device intended to be mounted on the boom of such an earth-moving machine, in particular a hydraulic excavator, preferably one with an offset boom, in order to measure not only a vertical angular movement, but also a horizontal angular movement of the boom on the hydraulic excavator.

As a secondary objective, the invention is aimed at an earth-moving machine equipped with such an angular movement conversion device.

A standard hydraulic excavator, used for jobs such as digging, excavating or backfilling, features an articulated arm that mimics the movement of a human arm. This articulated arm ends in a bucket, suitable for digging. The articulated arm is connected to the turret. The latter comprises a cab in which the operator is positioned and from which he controls the movement of the arm. A hydraulic excavator's articulated arm generally comprises a “boom” connected to one end to the turret, while the opposite end of this boom is articulated to the end of a “stick”. The bucket is placed at the opposite end of this stick.

The boom and stick are usually driven by respective hydraulic cylinders, notably in rotation around their joints. In the field of mechanical excavators, arms are known with a single-piece boom or a variable-angle boom, with or without an offset boom.

From the turret mounted on the chassis, the operator generally has access to a guidance system (including, for example, a dashboard) that provides him with information on several arm position parameters, such as bucket position, stick tilt and boom tilt. The operator has access to these measurements from inside the turret, limiting his dependence on the ground crew for real-time information.

Known excavator guidance systems may comprise angular movement sensors attached to the boom, bucket, etc., which measure vertical angular movement of the various arm portions relative to the frame, or relative to a portion of the boom, etc. The information acquired by these sensors can be relayed to the dashboard in the cab. For example, guidance is provided by GPS (Global Positioning System).

The boom of a hydraulic excavator is mounted on the turret, usually near the cab, by means of a boom foot, articulated around a horizontal axis. In some cases, this boom can also be pivoted around a vertical axis at this end, which is attached to the turret via a boom foot.

This gives the operator an extra degree of freedom to move the arm and bucket without altering the trajectory. This is known as an “offset boom” excavator, since the boom foot and its joint are offset from the turret. In this architecture, the boom foot has greater mobility relative to the turret and the rest of the hydraulic excavator chassis. Hydraulic excavators on the market, weighing less than 25 tons, often feature such an offset boom.

In an excavator equipped with an offset boom, the boom can pivot relative to the excavator frame, not only vertically (about an axis of rotation substantially parallel to the ground) but also horizontally (about an axis of rotation substantially orthogonal to the ground). To know the position and tilt of the boom, it is therefore necessary to measure the angular movement in real time in these two directions.

To provide these angle measurements, it has been proposed to equip the boom arm with a plurality of angular sensors, capable of positioning the bucket in relation to at least one other GNSS-type sensor (Global Navigation Satellite Systems) enabling real-time geolocation of the bucket. For example, a gravity-based angular sensor, such as a heated air bubble, is used for this purpose. However, such gravity sensors cannot determine horizontal angular movement, i.e. rotation about a vertical axis.

Accelerometer-type sensors are also used, but they are not suitable for slow movements, during which they tend to drift, so they need to be recalibrated each time.

To the best of the Applicant's knowledge, there is currently no simple, space-saving and inexpensive system for measuring the horizontal angular movement of the boom relative to the frame.

A first objective of the invention is to propose a system for guiding the arm of an earth-moving machine, which can address the problems raised above, and which is in particular better suited to controlling the position of the arm of an offset boom excavator.

An additional objective is to provide a machine incorporating a device for converting the horizontal angular movement of the boom about a substantially vertical axis of rotation (angular movement which is therefore performed horizontally). Combined with an angular measurement sensor, this conversion device must enable precise measurement, with little sensitivity to excavator vibrations and little sensitivity to the wear of the ring surrounding the boom's vertical axis of rotation.

In addition, the device is intended to be small and compact, so that it can be easily adapted to any type of hydraulic excavator.

A further aim is to offer a low-cost, simple-to-manufacture boom movement measuring device, particularly with regard to the angular sensor(s). It is preferable to reuse the same type of angular sensor that is already commonly used to measure the movement of a boom and/or stick and/or bucket and/or turret along the pitch or roll axis.

To meet these objectives, a first aspect of the invention relates to a sensor device with conversion of horizontal angular movement of a boom of an earth-moving machine, said device being intended to be mounted on the earth-moving machine and comprising a sensor holder comprising:

An angular movement conversion device as defined above may, optionally and without limiting the definition of the invention, have the following features taken alone or in combination.

According to a second aspect, the present invention relates to an earth-moving machine comprising a frame and a boom comprising a boom foot movable relative to said frame, said machine preferably being a hydraulic excavator, said machine further comprising a conversion device as defined above, comprising an angular movement sensor for measuring a movement of the boom relative to the frame about an axis, and further comprising a support rigidly connected to the frame, the angular movement sensor being mounted on said support.

With reference to, a hydraulic excavatoris shown as an example. The excavatorcomprises a chassis, mounted on rolling means, such as caterpillar tracks or wheels. A turret, also known as a frame, is mounted on this chassis, so that it can rotate about a vertical axis, and is topped by a cabhousing a operator's cockpit. An articulated armis also attached to this turret.

More particularly, the articulated armcomprises a stick, a first free endof which is equipped, by means of a joint, with a tool, here represented in the form of a bucket, at least rotatable about a horizontal axis. At its second endand by means of a joint, this stickis pivotably mounted about a horizontal axis of rotation on a first endof a boom, the opposite second endof which is articulated about a horizontal axis on a boom foot, by means of a joint.

It should be noted that the boommay be composed of a first boom member connected to the boom footand extended through a joint by a second boom member receiving the stick, a configuration not shown in the drawings.

Thus, the articulated armmay feature a jointbetween the bucketand stick, a jointbetween the stickand boom(or even between a first and a second boom member), and a jointbetween this boomand the boom foot. The individual parts are articulated together, for example, by a respective hydraulic cylinder.

In the case of an “offset boom” hydraulic excavator, this offsettingof the boom can take place at the boom foot. The boom footmay in turn can be attached to the turret or framevia a vertical rotation axis joint.

In the non-represented embodiment already mentioned, this offsetting of the boom is defined by a joint axis between the first and second members of a two-part boom.

In the case of an offset boomat the boom foot, this takes the form of a clevis which partly forms this joint.

As a result of this design, the boomcan be rotated relative to the turret or frame, mainly about the following two perpendicular axes:

In the event that the boomcomprises a first boom member articulated to a second boom member carrying the stick, the second boom member can also undergo angular movement, for example horizontally, relative to the boom base.

By way of illustration, [] shows the position of an axis C about which the second boom member can be rotated relative to the first boom member.

A devicefor converting the angular movement of the boomis described below. The deviceconverts the horizontal angular movement of the boomabout the axis B relative to the turret or frameinto vertical angular movement. This deviceis shown in. It is intended to be mounted on the boom, for example on the boom foot.

Alternatively, this conversion devicecould be used on another type of earth-moving machine.

The devicecomprises a sensor holder(described earlier) comprising a transmitter partwhich follows the horizontal angular movement of the boom. For example, the transmitter partcomprises a vertical hinge-shaped shaftmounted by welding or through a baseon the boom foot, preferably in the axial extension of the vertical pivot axis B (for horizontal movement) of this boom footrelative to the turret or frame.

A first horizontal flangeof a bracketis freely rotatably mounted on this shaftby means of a bearing, and is rigidly connected to the turret or frame. Consequently, as the boom footrotates relative to the turretaround the vertical pivot axis B defined by the jointconnecting it to the turret, the horizontal flangeof the bracketpivots around the shaft.

More particularly, this angleat least partly defines the sensor holder of the conversion device according to the invention. In particular, as shown in, the sensor holder can take the form of a box, with two;A of the perpendicular walls forming the bracket.

It should be noted that in an alternative example where the boomhas a first and second boom member articulated to each other about an axis C (as shown in), the transmitter partcould be mounted on one end of the second boom member, to track its angular movement about the axis C relative to the first boom member.

According to a first embodiment shown in, the transmitter partcomprises at least one driving discmounted in a rotationally fixed manner on the shaftto transmit the horizontal angular movement about the axis B (or about the axis C in the above-mentioned alternative example). This driving discbelongs to a mechanical transmission.

This mechanical transmission further comprises at least one driven discof a receiver partA, located on the other side of the transmission. This driven discis mounted to rotate on a shaftof the receiver partA, this shaftbeing mounted to rotate freely about a horizontal axis by means of a bearingA on the second flangeA, perpendicular to the first flange, of the bracket.

The mechanical transmissionfurther comprises a direct transmission element, transmitting motion from the driving discto the driven disc. In this first example, the transmission elementcomprises at least one connecting rod;connected by joints to the driving disc, on the one hand, and to the driven disc, on the other hand, so that a rotation of the first discabout the vertical axis B, corresponding to a horizontal movement, generates a rotation of the second discabout the horizontal axis A, corresponding to a vertical movement.

However, such an arrangement leads to movements of these discsandwhich are not proportional to the horizontal angular movement of the boom, but rather exponential.

As shown infor a second example, the discsandof the transmitter partand receiver partA, respectively, can be replaced by a driving pulleyA and a driven pulleyA, and the transmission elementby a beltA. The belt is wound partially around these pulleysA;A, bypassing a return rollerwhose axisextends perpendicular to the plane passing through the axes A and B, in order to reverse the strands of this beltA, from horizontal directions of movement around the driving pulleyA, into vertical directions of movement around the driven pulleyA.

It's easy to see that a cable and/or rope can be used instead of a belt.

illustrates a third design in which the mechanical transmissiontakes the form of a bevel gear, comprising, on the transmitter part, a bevel driving wheelB mounted in a rotationally fixed manner on the shaftand directly meshing with a bevel driven wheelB mounted in a rotationally fixed manner on the shaftof the receiver partA.

A horizontal angular movement of the boomabout the axis B is thus transmitted, via the mechanical transmission, whatever its form, from the transmitter partto the receiver partA, which then performs a vertical angular movement about axis A.

The angular conversion deviceis equipped with a receiving baseconfigured to receive a sensorfor angular movement of the receiver partA. The receiving baseis, for example, generally disk-shaped, or alternatively generally rectangular. It is mounted in a rotationally fixed manner on the shaftof this receiver partA. Thus, in relation to the second vertical flangeA of the angle, this receiving basecan be located on this shaft, either on the side of the driven disc, the driven pulleyA or the driven bevel gearB, or on the opposite side (preferred solution and shown on the figures). Note that the sensorcan be removably mounted on this receiving base.