SENSOR DEVICE WITH CONVERSION OF THE HORIZONTAL ANGULAR MOVEMENT OF A BOOM OF AN EARTH-MOVING MACHINE

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

See Application Data Sheet.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

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INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC OR AS A TEXT FILE VIA THE OFFICE ELECTRONIC FILING SYSTEM (EFS-WEB)

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STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINT INVENTOR

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BACKGROUND OF THE INVENTION

1. Field of the Invention

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.

2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98

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.

BRIEF SUMMARY OF THE INVENTION

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:

• • a transmitter part intended to be securely mounted on a part (16) of the boom;
  • a mechanical transmission configured to transmit to a receiver part a horizontal angular movement of said transmitter part with respect to a frame about a first axis, said receiver part then being moved angularly about a second axis perpendicular to the first axis;
  • the sensor holder being configured to receive at least one sensor, of the gravity and/or accelerometer type, designed to measure said angular movement of the receiver part about the second axis,
  • said sensor holder being mounted so as to be rigidly connected to the frame so as to rotate about the first axis.

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.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Further objectives and advantages of the invention will become apparent from the following description, which is given by way of illustration and is not limiting. This description is completed by the appended figures.

FIG. 1 shows a schematic view of an offset boom hydraulic excavator mounted on tracks, viewed from the side.

FIG. 2 shows a schematic view illustrating a horizontal boom angular movement conversion device according to a first example embodiment, the conversion device being mounted on an offset boom hydraulic excavator, the device being viewed from the side.

FIG. 3 shows a schematic view of an illustration of the same converter, seen from the side.

FIG. 4 is a schematic side view of a horizontal angular movement conversion device according to a second example embodiment.

FIG. 5 is a schematic front view of FIG. 4.

FIG. 6 is a schematic sectional view of FIG. 4.

FIG. 7 is a view similar to FIG. 6 of a conversion device according to a third example embodiment.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, a hydraulic excavator 1 is shown as an example. The excavator 1 comprises a chassis 2, mounted on rolling means 3, such as caterpillar tracks or wheels. A turret, also known as a frame 4, is mounted on this chassis 2, so that it can rotate about a vertical axis, and is topped by a cab 5 housing a operator's cockpit. An articulated arm 6 is also attached to this turret 4.

More particularly, the articulated arm 6 comprises a stick 7, a first free end 8 of which is equipped, by means of a joint 9, with a tool 10, here represented in the form of a bucket, at least rotatable about a horizontal axis. At its second end 11 and by means of a joint 12, this stick 7 is pivotably mounted about a horizontal axis of rotation on a first end 13 of a boom 14, the opposite second end 15 of which is articulated about a horizontal axis on a boom foot 16, by means of a joint 17.

It should be noted that the boom 14 may be composed of a first boom member connected to the boom foot 16 and extended through a joint by a second boom member receiving the stick 7, a configuration not shown in the drawings.

Thus, the articulated arm 6 may feature a joint 9 between the bucket 10 and stick 7, a joint 12 between the stick 7 and boom 14 (or even between a first and a second boom member), and a joint 17 between this boom 14 and the boom foot 17. The individual parts are articulated together, for example, by a respective hydraulic cylinder.

In the case of an “offset boom” hydraulic excavator, this offsetting 18 of the boom can take place at the boom foot 16. The boom foot 16 may in turn can be attached to the turret or frame 4 via a vertical rotation axis joint 19.

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 boom 18 at the boom foot 16, this takes the form of a clevis which partly forms this joint 19.

As a result of this design, the boom 14 can be rotated relative to the turret or frame 4, mainly about the following two perpendicular axes:

• • a first substantially vertical axis B, passing through the joint 19 of the boom foot 16 on this turret or frame 4 (which corresponds to a horizontal angular movement of the boom 14 parallel to the ground);
  • a second axis passing through joint 17, here perpendicular to first axis B, said axis being substantially parallel to the ground surface and passing through the boom foot 16 (which corresponds to a vertical angular movement of the boom 14 perpendicular to the ground).

In the event that the boom 14 comprises 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, [FIG. 1] shows the position of an axis C about which the second boom member can be rotated relative to the first boom member.

A device 20 for converting the angular movement of the boom 14 is described below. The device 20 converts the horizontal angular movement of the boom 14 about the axis B relative to the turret or frame 4 into vertical angular movement. This device 20 is shown in FIGS. 2 to 7. It is intended to be mounted on the boom 14, for example on the boom foot 16.

Alternatively, this conversion device 20 could be used on another type of earth-moving machine.

The device 20 comprises a sensor holder 25 (described earlier) comprising a transmitter part 21 which follows the horizontal angular movement of the boom 14. For example, the transmitter part 21 comprises a vertical hinge-shaped shaft 22 mounted by welding or through a base 23 on the boom foot 16, preferably in the axial extension of the vertical pivot axis B (for horizontal movement) of this boom foot 16 relative to the turret or frame 4.

A first horizontal flange 24 of a bracket 25 is freely rotatably mounted on this shaft 22 by means of a bearing 30, and is rigidly connected to the turret or frame 4. Consequently, as the boom foot 16 rotates relative to the turret 4 around the vertical pivot axis B defined by the joint 19 connecting it to the turret 4, the horizontal flange 24 of the bracket 25 pivots around the shaft 22.

More particularly, this angle 25 at least partly defines the sensor holder of the conversion device according to the invention. In particular, as shown in FIGS. 2 to 7, the sensor holder can take the form of a box, with two 24; 24A of the perpendicular walls forming the bracket 25.

It should be noted that in an alternative example where the boom 14 has a first and second boom member articulated to each other about an axis C (as shown in FIG. 1), the transmitter part 21 could 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 FIGS. 2 and 3, the transmitter part 21 comprises at least one driving disc 26 mounted in a rotationally fixed manner on the shaft 22 to transmit the horizontal angular movement about the axis B (or about the axis C in the above-mentioned alternative example). This driving disc 26 belongs to a mechanical transmission 27.

This mechanical transmission further comprises at least one driven disc 28 of a receiver part 21A, located on the other side of the transmission 27. This driven disc 28 is mounted to rotate on a shaft 29 of the receiver part 21A, this shaft 29 being mounted to rotate freely about a horizontal axis by means of a bearing 30A on the second flange 24A, perpendicular to the first flange 24, of the bracket 25.

The mechanical transmission 27 further comprises a direct transmission element 31, transmitting motion from the driving disc 26 to the driven disc 28. In this first example, the transmission element 31 comprises at least one connecting rod 32; 33 connected by joints to the driving disc 26, on the one hand, and to the driven disc 28, on the other hand, so that a rotation of the first disc 26 about the vertical axis B, corresponding to a horizontal movement, generates a rotation of the second disc 28 about the horizontal axis A, corresponding to a vertical movement.

However, such an arrangement leads to movements of these discs 26 and 28 which are not proportional to the horizontal angular movement of the boom 14, but rather exponential.

As shown in FIGS. 4, 5 and 6 for a second example, the discs 26 and 28 of the transmitter part 21 and receiver part 21A, respectively, can be replaced by a driving pulley 26A and a driven pulley 28A, and the transmission element 31 by a belt 32A. The belt is wound partially around these pulleys 26A; 28A, bypassing a return roller 34 whose axis 35 extends perpendicular to the plane passing through the axes A and B, in order to reverse the strands of this belt 32A, from horizontal directions of movement around the driving pulley 26A, into vertical directions of movement around the driven pulley 28A.

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

FIG. 7 illustrates a third design in which the mechanical transmission 27 takes the form of a bevel gear 36, comprising, on the transmitter part 21, a bevel driving wheel 26B mounted in a rotationally fixed manner on the shaft 22 and directly meshing with a bevel driven wheel 28B mounted in a rotationally fixed manner on the shaft 29 of the receiver part 21A.

A horizontal angular movement of the boom 14 about the axis B is thus transmitted, via the mechanical transmission 27, whatever its form, from the transmitter part 21 to the receiver part 21A, which then performs a vertical angular movement about axis A.

The angular conversion device 1 is equipped with a receiving base 37 configured to receive a sensor 38 for angular movement of the receiver part 21A. The receiving base 37 is, for example, generally disk-shaped, or alternatively generally rectangular. It is mounted in a rotationally fixed manner on the shaft 29 of this receiver part 21A. Thus, in relation to the second vertical flange 26A of the angle 25, this receiving base 37 can be located on this shaft 29, either on the side of the driven disc 26, the driven pulley 26A or the driven bevel gear 26B, or on the opposite side (preferred solution and shown on the figures). Note that the sensor 38 can be removably mounted on this receiving base 37.

Once positioned on the receiving base 37, it is configured to measure the vertical angular movement of the receiver part 21A relative to the transmitter part 21, and therefore of the turret or frame 4. The measurement frequency of the angular motion sensor 38 is between 50 Hertz and 150 Hertz, for example 100 Hertz.

An important advantage of the device 1 is that, for measuring horizontal angular movement, it is possible to use a standard sensor 38, of the gravity and/or accelerometer type, as is usually used to measure vertical angular movement of an excavator boom. The sensor 38 is, for example, a gravity-driven hot-air bubble angular sensor.

The conversion device 1, associated with such a sensor, can thus measure a horizontal angular movement of the excavator boom, and there is no need for a complex sensor specifically dedicated to this purpose.

An additional advantage is that the precision of the horizontal angular movement perceived by this device is not affected by any play that may exist at the joint 19 of the boom foot 16 on the turret or frame 4.

As explained above, the sensor holder 25 is rotatably mounted on the shaft 22, whose axis coincides with the axis B, corresponding to the axis of rotation of the boom foot 16 relative to the frame 4, in this case the turret. In addition, this sensor holder 25 is fixed relative to the frame 4. To this end, any connection means 39 capable of prevent this sensor holder 25 from rotating relative to the frame 4 can be used. FIGS. 3 and 5 show a threaded rod attached to the sensor holder 25, defining at least part of this connection means. However, it can take many other forms.

It should also be noted that the conversion device can be equipped with remote communication and/or wired connection means for transmitting information from the sensor 38 to a management unit, for example located in the operator's cab 5 and communicating with display means capable of informing the operator of the angular position of the boom 14 around the axis B. These display means may be those intended to give the operator other altimetric information on the position of the tool 10.