Luffing jib crane

Abstract

A luffing jib crane (1) comprising a mast (2) surmounted by a rotating section (4) orientable about a vertical axis (20) and comprising: - a rotating pivot (5) pivotally mounted on the mast; - a counter-jib (6) comprising a central section (60) and a horizontal radial section (61) directed rearward and fixed to the central section, which includes a base (64) fixed to the rotating pivot and a top (65) surmounting the base; - a luffing jib (7) directed forward and having a rear end (71) articulated on the base of the central section of the counter-jib, below the top, diametrically opposite to the radial section of the counter-jib; - a punch (8) fixed to the top of the central section of the counter-jib, and extending obliquely upward and rearward from the top. (Shorthand figure: Figure 1)

Description

Title of the invention: Luffing jib crane Technical field

[0001] The invention relates to a luffing jib crane.

[0002] It relates more particularly to a crane comprising a mast surmounted by a rotating part orientable around a vertical axis and comprising a rotating pivot pivotally mounted on the mast and on which is fixed a counter-jib, which counter-jib comprises a central section and a substantially horizontal radial section directed towards the rear and fixed on the central section, where the central section comprises a base fixedly mounted on the rotating pivot, and a top situated above the base along the vertical axis, a luffing jib directed towards the front and having a rear end articulated, around a horizontal axis, on the central section of the counter-jib, in a manner diametrically opposed to the radial section of the counter-jib, a punch fixed on the top of the central section of the counter-jib and extending obliquely upwards and towards the rear from this top. Prior art

[0003] Conventionally, in a luffing jib crane, a lifting winch is provided which comprises a lifting motor which rotates, in both directions and via a reduction gear, a lifting drum, around which is wound a lifting cable which passes over pulleys arranged at the top of the punch, and which also passes over the pulleys of a lifting block, located in front of the punch. The lifting block is connected, by a line of tie rods, to the luffing jib.

[0004] Thus, by rotating the motor in one direction or the other, the lifting cable makes it possible to raise or lower the luffing boom, between a low configuration in which the boom extends substantially horizontally, and a maximum raised configuration in which the boom is raised to its maximum while being inclined relative to the horizontal at an angle generally greater than 45 degrees.

[0005] It should be noted that conventionally the rear end of the luffing jib is articulated on the top of the central section of the counter-jib, in order to position the forces of the luffing jib at the foot of the punch, with the aim of controlling the forces on this part of the structure.

[0006] To improve the performance of a luffing jib crane, it is known to lengthen the punch. Indeed, a longer punch makes it possible to increase productivity by reducing the impact of the weight of the luffing jib on the tie rod line (improved lifting speed), and by reducing the weight of the luffing jib by a increase in the tie rod angle (which corresponds to the angle between the tie rod line and the luffing boom) and thus have an improved load curve.

[0007] However, increasing the length of the punch is not without constraints. Indeed, a longer punch takes up more space to transport, which may therefore require the use of a removable punch to remain transportable in a container or on a standard platform. In addition, a longer punch requires greater structural reinforcements on the counter-jib. Summary of the invention

[0008] The invention proposes to resolve the aforementioned drawbacks, by proposing a luffing jib crane architecture which makes it possible to improve performance without having to increase the length of the punch.

[0009] To this end, the invention proposes a luffing jib crane comprising a mast surmounted by a rotating part which can be oriented around a vertical axis and comprising: - a rotating pivot mounted pivotally on the mast; - a counter-jib comprising a central section and a substantially horizontal radial section directed towards the rear and fixed on the central section, which central section comprising a base fixedly mounted on the rotating pivot and a top surmounting the base and located above the base along the vertical axis; - a forward-facing luffing boom having a rear end hinged, about a horizontal axis, on the central section of the counter-jib, diametrically opposite the radial section of the counter-jib; - a punch fixed on the top of the central section of the counter-jib, and extending obliquely upwards and backwards from the top; said luffing jib crane being remarkable in that the rear end of the luffing jib is articulated on the base of the central section of the counter-jib, below the top along the vertical axis.

[0010] Thus, the invention proposes to transfer the articulation of the lifting boom as low as possible on the central section of the counter-jib, namely at the level of its base rather than at the level of its top. Thus, the length of the punch is fictitiously increased by the distance between the base and the top of the rotating pivot.

[0011] Thanks to this downward shift of the articulation of the luffing jib, the crane is greatly optimized with gains in terms of access, maintenance, force in the luffing cable and therefore productivity through a faster flight speed, reduction of force in the luffing jib and therefore reduction of weight, reduction of forces in the punch (compared to an equivalent punch) and therefore weight.

[0012] According to one characteristic, the central section of the counter-jib comprises: - a front structure extending obliquely upwardly and rearwardly and comprising an upper end at the top of the central section and a lower end at the base of the central section; and - a rear structure extending obliquely upwardly and rearwardly and comprising an upper end at the top of the central section and a lower end at the base of the central section; wherein the upper end of the front structure and the upper end of the rear structure are joined and secured to the top of the center section; and wherein the punch is fixed on the upper ends of the front structure and the rear structure and the rear end of the luffing boom is hinged on the lower end of the front structure.

[0013] According to one possibility, the punch extends in a punch direction which is inclined rearwardly with respect to the vertical axis at a punch angle of between 10 and 50 degrees, and the front structure of the central section of the counter-jib extends in a forward direction which is inclined rearwardly with respect to the vertical axis at a forward angle of between 5 and 40 degrees.

[0014] Advantageously, the punch angle and the front angle are between 0 and 20 degrees; so that the punch and the front structure of the central section of the counter-jib are substantially aligned, thus improving the fictitious increase in the length of the punch.

[0015] According to another possibility, the radial section of the counter-jib is fixed on the rear structure of the central section of the counter-jib.

[0016] According to another possibility, which the radial section of the counter-jib is fixed on the upper end and the lower end of the rear structure of the central section of the counter-jib.

[0017] In a particular embodiment, the front structure of the central section of the counter-jib comprises a right front arm and a left front arm extending parallel and obliquely upwards and rearwards, the right front arm and the left front arm having respective lower terminations forming the lower end of the front structure, and respective upper terminations forming the upper end of the front structure; and in which the rear end of the luffing boom is hinged to the lower ends of the right front arm and the left front arm.

[0018] In a particular embodiment, the rear structure of the central section of the counter-jib comprises a right rear arm and a left rear arm extending parallel and obliquely upwards and forwards, the right rear arm and the left rear arm having respective lower terminations forming the lower end of the rear structure, and respective upper terminations forming the upper end of the rear structure; wherein the upper termination of the right front arm is joined to the upper termination of the right rear arm, and the upper termination of the left front arm is joined to the upper termination of the left rear arm; and in which the punch is fixed on the upper ends of the front right arm, the rear right arm, the front left arm and the rear left arm.

[0019] According to one possibility, which the punch comprises a right oblique element and a left oblique element extending parallel and obliquely upwards and backwards, and in which the right oblique element is fixed on the upper terminations of the right front arm and the right rear arm, and the left oblique element is fixed on the upper terminations of the left front arm and the left rear arm. Brief description of the drawings

[0020] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of a non-limiting example of implementation, made with reference to the appended figures in which:

[0021] [Fig-1] is a schematic side and partial view of the rotating part of a luffing jib crane according to the invention, with the luffing jib in the raised configuration;

[0022] [Fig.2] is a schematic side and partial view of the rotating part of the crane at luffing boom of [Fig.l], with the luffing boom in the low configuration;

[0023] [Fig.3] is a schematic perspective and partial view of the rotating part of the luffing jib crane of [Fig.l], with the luffing jib in the raised configuration;

[0024] [Fig.4] is a schematic perspective and zoomed view of zone IV of [Fig.3]

[0025] [Fig.5] is a graph illustrating the variation of a force on the tie rod line in function of the reach on the boom, in a conventional luffing jib crane and in a luffing jib crane according to the invention.

[0026] [Detailed description of one or more embodiments of the invention]

[0027] With reference to Figures 1 to 4, a luffing jib crane 1 (hereinafter referred to as crane 1) comprises a base frame, fixed or mobile on the ground, above which rises a mast 2 which extends along a vertical axis 20. At the top of the mast 2 is mounted, by means of an orientation device 21, a rotating part 4 which can be oriented around the vertical axis 20 and mainly comprising a rotating pivot 5, a counter-jib 6, a luffing jib 7 and a punch 8.

[0028] The rotating pivot 5 is orientable around the vertical axis 20 of the mast 2, and it is pivotally mounted on the mast 2 by means of the orientation device 21. The rotating pivot 5 can support a driver's cabin of the crane 1.

[0029] The counter-jib 6 is fixedly mounted on the rotating pivot 5 in order to be integral in rotation with the latter. The counter-jib 6 comprises a central section 60 and a substantially horizontal radial section 61 directed towards the rear and fixed on the central section 60.

[0030] The radial section 61 has a platform for carrying equipment which includes, in particular, a lifting winch 90 for the luffing boom 7 and a lifting winch 91 for lifting loads. The radial section 61 also carries counterweights 63. This radial section 61 can be suspended from the punch 8, in its rear part, by means of connecting rods.

[0031] The lifting winch 90 has a drum, around which is wound a lifting cable which passes over pulleys arranged at the top of the punch 8, and which also passes over the pulleys of a lifting block (not shown), located in front of the punch 8. The lifting block is connected, by a line of tie rods (not shown), to the luffing boom 7.

[0032] The lifting winch 91 has a drum on which a lifting cable is wound, which is directed towards a pulley located at the tip of the luffing boom 7 and extends to a lifting hook (not shown), with or without a hauling system, the loads to be lifted being suspended from the hook when using the crane 1.

[0033] The central section 60 comprises a base 64 fixedly mounted on the rotating pivot 5 and a top 65 surmounting the base 64 and located above the base 64 along the vertical axis 20.

[0034] More specifically, the central section 60 comprises a front structure 66 which is formed of two front arms 660, and a rear structure 67 which is formed of two rear arms 670, where the two front arms 660 join the two respective rear arms 670 at the apex 65 of the central section 60 in order to have a general triangular shape for the central section 60.

[0035] The front arms 660 include a right front arm and a left front arm that extend parallel and obliquely upward and rearward. The rear arms 670 include a right rear arm and a left rear arm that extend parallel and obliquely upward and forward.

[0036] Each of these two front arms 660 comprises an upper termination 661 at the top 65 of the central section 60 and a lower termination 662 at the base 64 of the central section 60. The upper terminations 661 of these two front arms 66 form an upper end of the front structure 66, while the terminations lower 662 of these two front arms 660 form a lower end of the front structure 66.

[0037] Each of these two rear arms 670 comprises an upper termination 671 at the top 65 of the central section 60 and a lower termination 672 at the base 64 of the central section 60. The upper terminations 671 of these two rear arms 670 form an upper end of the rear structure 67, while the lower terminations 672 of these two rear arms 670 form a lower end of the rear structure 67.

[0038] The upper ends 661 of the two front arms 660 and the upper ends 671 of the two rear arms 670 are respectively secured to form together the top 65 of the central section 60. Also, the upper end of the front structure 66 and the upper end of the rear structure 67 are joined and secured to the top 65 of the central section 60.

[0039] The punch 8 is fixed on the apex 65 of the central section 60, and extends obliquely upwards and rearwards from the apex 65, in other words with a rearward inclination.

[0040] This punch 8 is therefore fixed on the upper ends of the front structure 66 and of the rear structure 67. More precisely, the punch 8 comprises a right oblique element 81 and a left oblique element 82 extending parallel and obliquely upwards and backwards, and the right oblique element 81 is fixed on the upper ends 661, 671 of the right front arm 660 and of the right rear arm 670, and the left oblique element 82 is fixed on the upper ends 661, 671 of the left front arm 660 and of the left rear arm 670.

[0041] The punch 8, and more precisely its two oblique elements 81, 82, extend in a punch direction 80 which is inclined rearwardly relative to the vertical axis 20 at a punch angle A8 of between 10 and 50 degrees, and the front arms 660 of the front structure 66 extend in a front direction 600 which is inclined rearwardly relative to the vertical axis 20 at a front angle A6 of between 5 and 40 degrees. Advantageously, the difference between the punch angle A8 and the front angle A6 is between 0 and 20 degrees, in other words IA8 - A6I < 20 degrees. Thus, the punch 8 and the front arms 660 are substantially aligned.

[0042] The lower ends 662 of the two front arms 660 and the lower ends 672 of the two rear arms 670 are connected by bars to together form the base 64 of the central section 60.

[0043] The luffing boom 7 is directed forward and has a rear end 71 articulated, about a horizontal axis, on the central section 60 of the counter-jib 6, in a manner diametrically opposed to the radial section 61 of the counter-jib 6. The rear end 71 of the luffing boom 7 is articulated on the base 64 of the central section 60, below the top 65 along the vertical axis 20. More precisely, the rear end 71 of the lifting boom 7 is articulated on the lower end of the front structure 66, and in particular on the lower ends 662 of the two front arms 660.

[0044] Thus, the rear end 71 of the lifting boom 7 is offset downwards compared to the top 65 of the central section 60, on which the punch 8 is fixed. In this way, the two front arms 660 form extensions of the respective oblique elements 81, 82 of the punch 8, thus making it possible to fictitiously increase the length of the punch 8 by the length L6 of the front arms 660 or of the front structure 66.

[0045] The lifting boom 7 comprises a lattice structure, for example of triangular section. The radial section 61 also comprises a lattice structure, for example of triangular section.

[0046] This radial section 61 comprises upper beams 610 which are fixed on the upper ends of the front structure 66 and of the rear structure 67. More precisely, these upper beams 610 comprise an upper beam on the right and an upper beam on the left which extend parallel and substantially horizontally towards the rear, and the upper beam on the right is fixed on the upper ends 661, 671 of the front arm on the right 660 and of the rear arm on the right 670, and the upper beam on the left is fixed on the upper ends 661, 671 of the front arm on the left 660 and of the rear arm on the left 670.

[0047] This radial section 61 comprises lower beams 611 which are fixed on the lower ends of the rear structure 67. More precisely, these lower beams 611 comprise a lower beam on the right and a lower beam on the left which extend parallel towards the rear, and the lower beam on the right is fixed on the lower end 672 of the rear arm on the right 670, and the lower beam on the left is fixed on the lower end 672 of the rear arm on the left 670.

[0048] [Fig. 5] illustrates a first curve C1 of variation of a force on the tie rod line ET as a function of the span P on the luffing jib in a conventional luffing jib crane, i.e. in which the rear end of the luffing jib is articulated on the top 65 of the central section 60 of the counter-jib 6, and a second curve C2 of variation of a force on the tie rod line ET as a function of the span P on the luffing jib in a luffing jib crane 1 as described above, i.e. in which the rear end 71 of the luffing jib 7 is articulated on the base 64 of the central section 60 of the counter-jib 6.

[0049] Thus, it is worth noting a reduction of the order of 15% of the force on the tie rod line ET thanks to the positioning of the articulation of the rear end 71 of the boom lifting 7 on the base 64, which makes it possible to refine and therefore optimize the structures of the counter-arrow 6 and the punch 8.

Claims

Claims

1. Luffing jib crane (1) comprising a mast (2) surmounted by a rotating part (4) orientable around a vertical axis (20) and comprising: - a rotating pivot (5) pivotally mounted on the mast (2); - a counter-jib (6) comprising a central section (60) and a substantially horizontal radial section (61) directed towards the rear and fixed on the central section (60), which central section (60) comprises a base (64) fixedly mounted on the rotating pivot (5) and a top (65) surmounting the base (64) and located above the base (64) along the vertical axis (20); - a lifting boom (7) directed forwards and having a rear end (71) articulated, around a horizontal axis, on the central section (60) of the counter-jib (6), diametrically opposite the radial section (61) of the counter-jib (6);- a punch (8) fixed on the top (65) of the central section (60) of the counter-jib (6), and extending obliquely upwards and backwards from the top (65); said luffing jib crane (1) being characterized in that the rear end (71) of the luffing jib (7) is articulated on the base (64) of the central section (60) of the counter-jib (6), below the top (65) along the vertical axis (20).;

2. A luffing jib crane (1) according to claim 1, wherein the central section (60) of the counter-jib (6) comprises: - a front structure (66) extending obliquely upwards and backwards and comprising an upper end at the top (65) of the central section (60) and a lower end at the base (64) of the central section (60); and - a rear structure (67) extending obliquely upwards and backwards and comprising an upper end at the top (65) of the central section (60) and a lower end at the base (64) of the central section (60); wherein the upper end of the front structure (66) and the upper end of the rear structure (67) are joined and secured to the top (65) of the central section (60); and wherein the punch (8) is fixed on the upper ends of the front structure (66) and the rear structure (67) and the end rear (71) of the luffing boom (7) is articulated on the lower end of the front structure (66).

3. A luffing jib crane (1) according to claim 2, wherein the punch (8) extends in a punch direction (80) which is inclined rearwardly with respect to the vertical axis (20) at a punch angle (A8) of between 10 and 50 degrees, and the front structure (66) of the central section (60) of the counter-jib (6) extends in a front direction (600) which is inclined rearwardly with respect to the vertical axis (20) at a front angle (A6) of between 5 and 40 degrees.

4. A luffing jib crane (1) according to claim 3, wherein the deviation between the punch angle (A8) and the front angle (A6) is between 0 and 20 degrees.

5. A luffing jib crane (1) according to any one of claims 2 to 4, wherein the radial section (61) of the counter-jib (6) is fixed to the rear structure (67) of the central section (60) of the counter-jib (6).

6. A luffing jib crane (1) according to claim 5, wherein the radial section (61) of the counter-jib (6) is fixed on the upper end and the lower end of the rear structure (67) of the central section (60) of the counter-jib (6).

7. A luffing jib crane (1) according to any one of claims 2 to 6, wherein the front structure (66) of the central section (60) of the counter-jib (6) comprises a right-hand front arm (660) and a left-hand front arm (660) extending parallel and obliquely upwards and backwards, the right-hand front arm (660) and the left-hand front arm (660) having respective lower terminations (662) forming the lower end of the front structure (66), and respective upper terminations (661) forming the upper end of the front structure (66); and wherein the rear end (71) of the luffing jib (7) is hinged to the lower terminations (662) of the right-hand front arm (660) and the left-hand front arm (660).

8. A luffing jib crane (1) according to claim 7, wherein the rear structure (67) of the central section (60) of the counter-jib (6) comprises a right rear arm (670) and a left rear arm (670) extending parallel and obliquely upwards and forwards, the right rear arm (670) and the left rear arm (670) having respective lower terminations (672) forming the lower end of the rear structure (67), and respective upper terminations (671) forming the upper end of the rear structure (67); wherein the upper termination (661) of the right front arm (660) is joined to the upper termination (671) of the right rear arm (670), and the upper termination (661) of the left front arm (660) is joined to the upper termination (671) of the left rear arm (670); and wherein the punch (8) is fixed on the upper terminations (661, 671) of the right front arm (660), the right rear arm (670), the left front arm (660) and the left rear arm (670).

9. A luffing jib crane (1) according to claim 8, wherein the punch (8) comprises a right oblique member (81) and a left oblique member (82) extending parallel and obliquely upward and backward, and wherein the right oblique member (81) is fixed on the upper ends (661, 671) of the right front arm (660) and the right rear arm (670), and the left oblique member (82) is fixed on the upper ends (661, 671) of the left front arm (660) and the left rear arm (670).