VERTICAL LIFTING ARRANGEMENT FOR CONSTRUCTION MACHINE

Abstract

A lifting arrangement for a construction machine includes a frame arrangement with a front frame portion and a rear frame portion. The lifting arrangement is mountable to the front frame portion and comprises a main arm including a pivot connector and an equipment connector and a main arm support means for pivotably supporting the pivot connector. The main arm support means is movable in a front-rear direction with respect to the frame arrangement. The equipment connector, upon pivoting the main arm between a lowered position and a lifted position, follows a substantially vertical path. The lifting arrangement comprises a tilting arrangement for tilting an equipment mounted to the equipment connector. The tilting arrangement comprises a kinematic chain for attachment to a tilting connector of the equipment mounted to the equipment connector. The kinematic chain comprises a tilting link and a connecting link pivotably connected to each other.

Claims

1. A lifting arrangement for a construction machine having a frame arrangement including a front frame portion and a rear frame portion, the lifting arrangement being mountable to the front frame portion, the lifting arrangement comprising: a main arm provided with a pivot connector at a proximate end thereof and an equipment connector at a distal end thereof; and a main arm support means for pivotably supporting the pivot connector of the main arm, wherein the main arm support means is movable in a direction which includes at least a component in a front-rear direction with respect to the frame arrangement; wherein the lifting arrangement is configured such that the equipment connector, upon pivoting the main arm between a lowered position and a lifted position, follows a substantially vertical path; the lifting arrangement further comprising: a tilting arrangement for tilting an equipment mounted to the equipment connector of the main arm, the tilting arrangement comprising a kinematic chain for attachment to a tilting connector of the equipment mounted to the equipment connector of the main arm, a tilting actuator, and a connector connecting the kinematic chain and the tilting actuator, wherein the kinematic chain is positioned above the main arm in the lowered position and the tilting actuator is positioned below the main arm in the lowered position, and wherein the kinematic chain comprises a tilting link and a connecting link pivotably connected to each other.

2. The lifting arrangement according to claim 1, wherein the connector is a lever pivotably supported by the main arm, the lever comprising an upper connector provided above the main arm and a lower connector provided below the main arm.

3. The lifting arrangement according to claim 2, wherein the tilting link connects the tilting connector of the equipment to the connecting link connected to the upper connector of the lever.

4. The lifting arrangement according to claim 3, wherein the tilting arrangement further comprises a guiding link, and wherein one end of the guiding link is pivotably supported by the main arm and another end of the guiding link is pivotably supported by the kinematic chain.

5. The lifting arrangement according to claim 4, wherein the guiding link is pivotably connected to the tilting link of the kinematic chain.

6. The lifting arrangement according to claim 1, wherein the equipment includes a bucket comprising: a main arm connector connected to the equipment connector of the main arm; and the tilting connector connected to the tilting link of the tilting arrangement, wherein the tilting connector is situated above the main arm connector.

7. The lifting arrangement according claim 1, wherein the tilting actuator comprises a tilting cylinder for actuation of a tilting movement of the equipment connected to the equipment connector of the main arm.

8. The lifting arrangement according to claim 7, wherein the tilting cylinder is situated below the main arm in all normal operating conditions of the lifting arrangement.

9. The lifting arrangement according to claim 7, wherein the connector is a lever pivotably supported by the main arm, the lever comprising an upper connector provided above the main arm and a lower connector provided below the main arm, and wherein the tilting cylinder is connected to the lower connector of the lever.

10. The lifting arrangement according to claim 7, wherein the tilting cylinder is connectable to the front frame portion of the frame arrangement or the main arm support means.

11. The lifting arrangement according to claim 1, further comprising a first self-level link and a second self-level link longer than the first self-level link, wherein the first self-level link is attached to the main arm support means, the second self-level link, and the tilting actuator; and wherein the second self-level link is attached to the front frame portion, the first self-level link, and the tilting actuator.

12. The lifting arrangement according to claim 1, further comprising a guiding means engaged to the main arm at a guided portion of the main arm positioned between the pivot connector and the equipment connector, wherein upon pivoting the main arm between the lowered position and the lifted position, the guiding means guides the main arm such that the equipment connector follows a substantially vertical path.

13. The lifting arrangement according to claim 1, further comprising: a main arm actuating element engaged to the main arm and an auxiliary actuating element engaged to the main arm support means for moving the equipment connector between the lowered position and the lifted positions; a determining means for determining a lifting related quantity reflecting a position of the equipment connector with respect to the front frame portion; and a control means for controlling an operation of the main arm actuating element and the auxiliary actuating element based on a determined lifting related quantity, such that a path of the equipment connector upon moving between the lowered position and the lifted position follows a substantially vertical path.

14. A construction machine having an articulating frame arrangement consisting of a front frame portion and a rear frame portion articulatingly interconnected for providing an articulating steering, the construction machine comprising: a lifting arrangement comprising: a main arm provided with a pivot connector at a proximate end thereof and an equipment connector at a distal end thereof; a main arm support means for pivotably supporting the pivot connector of the main arm wherein the main arm support means is movable in a direction which includes at least a component in a front-rear direction with respect to the articulating frame arrangement, and wherein the lifting arrangement is configured such that the equipment connector, upon pivoting the main arm between a lowered position and a lifted position, follows a substantially vertical path; and a tilting arrangement for tilting an equipment mounted to the equipment connector of the main arm, the tilting arrangement comprising a kinematic chain for attachment to a tilting connector of the equipment mounted to the equipment connector of the main arm, a tilting actuator, and a connector connecting the kinematic chain and the tilting actuator, wherein the kinematic chain is positioned above the main arm in the lowered position and the tilting actuator is positioned below the main arm in the lowered position, and wherein the kinematic chain comprises a tilting link and a connecting link pivotably connected to each other.

15. The construction machine according to claim 14, wherein the lifting arrangement is supported by the front frame portion of the articulating frame arrangement and is articulated together with the front frame portion with respect to the rear frame portion upon steering.

16. The construction machine according to claim 14, wherein the connector is a lever pivotably supported by the main arm, the lever comprising an upper connector provided above the main arm and a lower connector provided below the main arm.

17. The construction machine according to claim 16, wherein the tilting link connects the tilting connector of the equipment to the connecting link connected to the upper connector of the lever.

18. The construction machine according to claim 17, wherein the tilting arrangement further comprises a guiding link, and wherein one end of the guiding link is pivotably supported by the main arm and another end of the guiding link is pivotably supported by the kinematic chain.

19. The construction machine according to claim 18, wherein the guiding link is pivotably connected to the tilting link of the kinematic chain.

20. The construction machine according to claim 14, wherein the equipment includes a bucket comprising: a main arm connector connected to the equipment connector of the main arm; and the tilting connector connected to the tilting link of the tilting arrangement, wherein the tilting connector is situated above the main arm connector.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 illustrates a construction machine equipped with a vertical lifting arrangement according to a first embodiment in a lowered position;

[0027] FIG. 2 illustrates a construction machine equipped with a vertical lifting arrangement according to the first embodiment in an intermediate position;

[0028] FIG. 3 illustrates a construction machine equipped with a vertical lifting arrangement according to the first embodiment in a lifted position;

[0029] FIG. 4 illustrates a first embodiment of the tilting arrangement of the vertical lifting arrangement of the construction machine according to the first embodiment in perspective view;

[0030] FIG. 5 illustrates the tilting arrangement of FIG. 4 in side view in a lowered position;

[0031] FIG. 6 illustrates schematically the tilting arrangement of FIG. 4 in side view in a lifted position;

[0032] FIG. 7 illustrates a second embodiment of the tilting arrangement of the vertical lifting arrangement of the construction machine according to the first embodiment in perspective view;

[0033] FIG. 8 illustrates the tilting arrangement of FIG. 7 in side view.

[0034] FIG. 9 illustrates a construction machine equipped with a vertical lifting arrangement according to a second embodiment in a lowered position;

[0035] FIG. 10 illustrates a construction machine equipped with a vertical lifting arrangement according to the second embodiment in an intermediate position;

[0036] FIG. 11 illustrates a construction machine equipped with a vertical lifting arrangement according to the second embodiment in a lifted position;

[0037] FIG. 12 illustrates components of the control system applied to the lifting arrangement according to the second embodiment;

[0038] FIG. 13 illustrates a third embodiment of the tilting arrangement of the vertical lifting arrangement of the construction machine according to the second and first embodiment in perspective view.

DETAILED DESCRIPTION OF EMBODIMENTS

[0039] In the following, embodiments of the present invention are explained in detail based on the drawings. It is noted that the below discussed embodiments can be combined with each other and the invention is not specifically restricted to the structure and arrangement of the specific embodiments and modifications discussed below.

General Overview

[0040] The present invention relates to a lifting arrangement comprising a tilting arrangement which is applicable to construction machines in general. In the following embodiments, the lifting arrangement is illustrated and explained as structure of a construction machine which is embodied as wheel loader. However, the specific application of the lifting arrangement according to the present invention is not limited to the application to a wheel loader. Rather, the lifting arrangement according to the present invention can be applied to drivable construction machines of any type such as loaders having wheels or crawler track chains or even a combination of both. Moreover, the steering type is not limited to the below discussed optional articulating steering arrangement. Rather, the lifting arrangement is applicable to construction machines having any type of steering arrangements such as articulating steering arrangements, skid steering arrangements or any other type.

[0041] The construction machine to which the lifting arrangement according to the present invention is applicable is briefly explained based on the illustration of FIG. 1. FIG. 1 shows the construction machine 1 in a simplified side view. Elements which are not essential for the invention are omitted. FIG. 1 does not illustrate the tilting arrangement of the lifting arrangement of the construction machine. Embodiments of the tilting arrangement of the construction machine are illustrated in FIGS. 4-7.

[0042] The construction machine 1 comprises a front frame portion 30 and rear frame portion 20. In the example according to FIG. 1, a pair of front wheels 301 is mounted to the front frame portion 30 and a pair of rear wheels 201 is mounted to the rear frame portion 20. The front frame portion 30 is mounted to the rear frame portion 20 with an articulating steering arrangement 40. The articulating steering arrangement 40 is well known to the skilled person and comprises one or multiple bearings for providing an articulating mount between the front frame portion 30 and the rear frame portion 20 with a pivoting axis being arranged substantially along the vertical axis of the construction machine 1, i.e. perpendicular with respect to the longitudinal direction of the construction machine 1. The articulating steering arrangement 40 provides a tilting between the front frame portion 30 and the rear frame portion 20 in order to provide a steering by changing the angle enclosed between the rotation axis of the front wheels 301 and the rotating axis of the rear wheels 201. The articulating steering arrangement 40 can be driven by a not illustrated actuator, such as a hydraulic actuator. The type and structure of the articulating steering arrangement 40 is not essential to the invention and can be adapted as required.

[0043] The construction machine 1 according to the example shown in FIG. 1 comprises an operator's cab 203 which is mounted to the rear frame portion 20. Inside the operator's cab 203, space for the operator is provided and the required operating and control elements which are not illustrated are accessible by the operator. The operator's cab 203 comprises not illustrated windows in order to provide visibility of the surrounding field for the operator.

[0044] An engine compartment 202 is provided at the rear frame portion 20 which houses one or multiple power sources for providing power required to operate the construction machine 1. The power sources can include but are not limited to an internal combustion engine, such as a Diesel engine, which can be coupled to further equipment such as hydraulic pumps, generators and the like. The power source is used to provide power for driving the front wheels 301 and/or the rear wheels 201 as well as for providing power for actuators besides other elements of the construction machine.

[0045] The front frame portion 30 extends in the forward direction with respect to the rear frame portion 20. In the present example, the front frame portion 30 is located in front of the operator's cab 203 and the engine compartment 202. However, the application of the lifting arrangement according to the present invention is not limited to the construction machine 1 having such an arrangement.

[0046] Upon a steering operation, the front frame portion 30 tilts with respect to the rear frame portion 20, the operator's cab 203 and the engine compartment 202. However, it is also possible to provide a modified steering arrangement such as a single wheel steering, front wheel steering or rear wheel steering while the articulating steering arrangement is omitted or provided only as option.

[0047] In the following, the lifting arrangement according to the present invention is explained in three embodiments, wherein the lifting arrangement is mounted to the front frame portion 30 of the above explained exemplary construction machine 1 embodied as wheel loader.

First Embodiment

[0048] The lifting arrangement according to the first embodiment will now be explained with reference to FIGS. 4 to 6. The lifting arrangement comprises a main arm 3 having a pivot connector 4 at a proximate end and an equipment connector 5 at a distal end thereof. The pivot connector 4 is pivotally supported at a main arm support means 6 which includes a main arm support link 6a in the present embodiment. The main arm support link 6a has a first end 12 and a second end 13, the first end 12 being pivotably connected to the pivot connector 4 of the main arm 3 and the second end 13 being pivotably connected to an element of the front frame portion 30. The connection between the pivot connector 4 of the main arm 3 and the first end 12 of the main arm support link 6a can be provided as bearing arrangement of a suitable type in order to provide a sliding rotation of the main arm 3 with respect to the main arm support link 6a.

[0049] The main arm support link 6a is pivotably mounted to the front frame portion 30 at its second end 13. In order to provide such a pivotable mount of the main arm support link 6a to the front frame portion 30, a rotating bearing of a suitable type is arranged for providing the pivotable movement of the main arm support link 6a with respect to the front frame portion 30.

[0050] The main arm support link 6a is arranged such that a rotation or pivoting movement of the main arm support link 6a provides a movement of the first end 12 in a direction which at least includes a component in the front-rear direction of the construction machine 1. For this reason, the main arm support link 6a is directed in an upwards direction with a specific inclination from the vertical direction in the situation in FIG. 1.

[0051] The main arm 3 comprises a guided portion 10 which is provided between the pivot connector 4 and the equipment connector 5. In the present embodiment, the guided portion 10 is also offset by a predetermined amount from a line connecting the pivot connector 4 and the equipment connector 5. However, this offset is not essential for the present invention and rather a preferred arrangement.

[0052] The lifting arrangement according to the present invention further includes a guiding means 7 which includes in the embodiment shown in FIG. 1 a guiding arm 7a having a first end 8 and a second end 9. The first end 8 is pivotably mounted to the front frame portion 30 and the second end 9 is pivotably mounted to the main arm 3 at the guided portion 10. The second end 9 is pivotably mounted to a bearing of a suitable type provided in the area of the guided portion 10 of the main arm 3 in order to provide a pivotable movement of the guiding arm 7a relative to the main arm 3. On the other hand, the first end 8 is pivotably mounted to the front frame portion with a bearing of a suitable type in order to provide a pivotable movement of the guiding arm 7a with respect to the front frame portion.

[0053] An actuator 11 is provided in the lifting arrangement. The actuator has a first end 11b which is pivotably mounted to the front frame portion 30 and a second end 11a which is pivotably mounted to the main arm 3. The actuator is embodied as linear actuator such as a hydraulic actuator in the present embodiment but not limited thereto. Upon operating the actuator 11, the distance between the first end 11b and the second end 11a can be changed e.g. by introducing pressurized fluid into pressure chambers of the actuator 11.

[0054] At the equipment connector 5 of the main arm 3, a bucket 15 is provided which is an example of equipment which can be mounted to the main arm. The bucket comprises a main arm connector for connection to the equipment connector 5 of the main arm 3 and a tilt connector 151 for tiltably operating the bucket. The tilt connector 151 is provided above the main arm connector. The tilting arrangement of this first embodiment for tilting the bucket 15 is not illustrated in FIGS. 1-3 and will be explained in further detail below.

[0055] In the exemplary arrangement shown in FIG. 1, the guiding arm 7a is directed rearwards with respect to the first end 8 of the guiding arm 7a. In FIG. 1, the lifting arrangement is shown in a position which is defined as lowered position in which the bucket is positioned at a lowermost position in which the bucket is able to admit material to be lifted and touches the ground. It is, however, possible to provide a lifting range which extends below the ground limit if needed.

[0056] In the following, an operation of the lifting arrangement according to the present invention is explained in detail based on the illustrations of FIGS. 1-3.

[0057] In FIG. 1, the lifting arrangement is illustrated in the lowered position. In this situation, the main arm is rotated downwards as illustrated in FIG. 1. This is achieved by retracting the actuator 11 which is provided for operating the main arm 3. The position of the main arm 3 is determined by the linkage between the guiding arm 7a and the main arm support link 6a. In other words, the position of the pivot connector 4 of the main arm 3 can be changed by changing the rotational position of the main arm support link 6a, whereas the guiding arm 7a determines, due to its rotational connection between the front frame portion 30 and the guided portion 10 of the main arm 3, the position of the pivot connector 4 depending on the rotational position of the main arm 3. As such, the lifting arrangement provides a link-based transmission which uniquely determines the position of the main arm 3.

[0058] Upon actuating the actuator 11, the main arm 3 is rotated in the clockwise direction in FIG. 1. With this rotation, the main arm 3 is rotated with respect to the main arm support link 6a. At the same time, the guiding arm 7a is rotated in the counter clockwise direction. When the guiding arm 7a rotates in the counter clockwise direction, the guided portion 10 of the main arm 3 is forced along a circular path due to the constant distance between the first and second ends 8, 9 of the guiding arm 7a. The circular path provided by the rotation of the guiding arm 7a is bulged towards the main arm support means including, in the present embodiment, the main arm support link 6a.

[0059] FIG. 2 shows the lifting arrangement of FIG. 1 in an intermediate position which is lifted from the lowered position by a predetermined amount. As can be seen, the guiding arm 7a is rotated from the position shown in FIG. 1 in the counter clockwise direction. In this context, the position of the second end 9 of the guiding arm 7a has moved with a component of movement in the rearward direction with respect to the construction machine 1. In the same context, the main arm 3 has rotated in the clockwise direction and the bucket 15 mounted to the equipment connector has lifted by a predetermined amount. Due to the fact, that the guided portion 10 of the main arm 3 is forced in the rearward direction by the predetermined movement path of the second end 9 of the guiding arm 7a, the main arm support link 6a is rotated in the clockwise direction about its second end 13 which is mounted to the front frame portion 30. Therefore, the position of the first end 12 of the main arm support link 6a is moved together with the pivot connector 4 of the main arm 3 in the rearward direction with respect to the construction machine.

[0060] Upon a further operation of the actuator 11, the main arm 3 is further rotated in the clockwise direction and reaches a lifted position shown in FIG. 3. In this position, the bucket 15 mounted to the equipment connector 5 of the main arm 3 has reached a position which is higher than the intermediate position shown in FIG. 2. This position is the maximum lift position of the bucket 15 which can be achieved with the embodiment shown in FIGS. 1-3. Upon further rotating the main arm 3 in the clockwise direction, the guiding arm 7a is further rotated in the counterclockwise direction and forces the guided portion 10 of the main arm 3 further along the circular path. As the second end 9 of the guiding arm 7a has moved forward with respect to the position shown in FIG. 2, the main arm support link 6a is rotated in the counterclockwise direction from the position shown in FIG. 2. Therefore, the position of the first end 12 supporting the pivot connector 4 of the main arm 3 is further forward compared to the position thereof shown in FIG. 2.

[0061] Based on the above operation, the bucket 15 can be moved from the lowered position shown in FIG. 1 to the lifted position shown in FIG. 3 through the intermediate position shown in FIG. 2. Based on the inventive arrangement comprising the guiding arm 7a and the main arm support link 6a , the equipment connector 5 is forced along a predetermined movement path which is shown as path P in the drawings. In the present illustration, the path P is formed with an S-shape but basically follows a substantially vertical path throughout the movement of the equipment connector from the lower most position to the upper most position. The substantially vertical path may be a J-shaped path. In particular, the path P deviates from a circular path which is achievable with prior art lifting arrangements in which the pivot connector 4 of the main arm 3 is immovably and stationary with respect to a frame portion of the construction machine 1. According to the present invention, the movement of the pivot connector 4 of the main arm is achieved by providing the movable support means 6 and the guiding means 7 which forces the main arm 3 to a specified movement pattern leading to a basically vertical movement range of the equipment connector 5.

[0062] Furthermore, the lifting arrangement according to this first embodiment comprises a tilting arrangement 400 for tilting the bucket 15 connected to the equipment connector 151 of the main arm 3. FIGS. 4-5 illustrate a first embodiment of this tilting arrangement 400. The tilting arrangement 400 comprises a lever 401, which is pivotably supported by the main arm 3. Specifically, the main arm 3 comprises a pivot connector 402 for supporting the lever 401. The pivot connector 402 may be provided at a connection piece 403, which extends between two parallel main arm carriers. The connection piece 403 may be provided in the middle of the main arm length extension. Preferably, the pivot connector 402 for supporting the lever 401 is provided at the upper end, i.e. the end which faces towards the wheel loader, of the connection piece 403. In this preferred embodiment, the pivot connector 402 may be provided in the upper half of the length extension of the main arm 3.

[0063] The lever 401 comprises a lower connector 404, which is positioned below the main arm 3, and an upper connector 405, which is positioned above the main arm 3. Preferably, the distance from the upper connector 405 of the lever 401 to the pivot connector 402 for supporting the main arm 3 is larger than the distance from the lower connector 404 to the pivot connector 402. Thus, the lever 401 according to this preferred embodiment exhibits a transmission ratio. In other words, due to the different distances from upper 405 and lower connectors 404 to the pivot connector 402 for supporting the lever 401, a relatively small movement path of the lower connector 404 with a relatively large force leads to a relatively large movement path of the upper connector 405 with a relatively small force.

[0064] Furthermore, the tilting arrangement 400 comprises a kinematic chain 406. The kinematic chain 406 is connected to the upper connector 405 of the lever 401 and the tilt connector 151 of the bucket 15. Thus, the kinematic chain 406 transmits a movement of the upper connector 405 of the lever 401 to the tilt connector 151 of the bucket 15. In this embodiment, the kinematic chain 406 comprises a tilting link 407 and a connection link 408, which are pivotably connected to each other. The length of the connection link 408 may be more than twice the length of the tilting link 407. The tilting link 407 is further connected to the tilt connector 151 of the bucket 15. The connection link 408 is further connected to the upper connector 405 of the lever 401. The complete kinematic chain 406 is provided above the main arm 3. Specifically, in all normal operating conditions of the lifting arrangement, the kinematic chain 406 never extends into a region below the main arm 3. Thus, there is no risk of interference between the tilting link 407/the kinematic chain 406 and the front axle and front wheel 301 of the construction machine, respectively. Accordingly, the tilting arrangement 400 according to this embodiment does not restrain bucket rollback in any normal operating condition of the lifting arrangement due to its provision above the main arm 3.

[0065] In addition, the tilting arrangement 400 according to this embodiment comprises a guiding link 409. The guiding link 409 is pivotably supported by the main arm and the tilting link 407 of the kinematic chain 406. The guiding link 409 ensures a specific movement pattern of the tilt connector 151, thereby allowing for large tilting forces. The guiding link 409 may be supported at the lower end, i.e. the end that faces away from the construction machine, of the connection piece 403 of the main arm 3.

[0066] Furthermore, the tilting arrangement 400 comprises a tilting cylinder 410 for actuation of a tilting movement of the bucket 15. The tilting cylinder 410 is connected to the lower connector 404 of the lever 401 and extends from this lower connector 404 towards the construction machine. In this embodiment, the tilting cylinder 410 is completely provided below the main arm 3. Furthermore, in this embodiment, the tilting cylinder 410 is connected to the front frame portion 30 of the articulating frame arrangement. Thus, the main arm 3 and the main arm support means 6 do not have to carry the weight of the tilting cylinder 410 upon movement of the bucket 15 between lowered and lifted position.

[0067] For tilting the bucket 15, the tilting cylinder 410 is actuated, thereby moving the lower connector 404 of the lever 401 to which it is connected. The movement of the lower connector 404 leads to a rotation of the lever 401 around the pivot connector 402, which moves the upper connector 405 of the lever in a direction opposite to that of the lower connector 404 movement. The movement of the upper connector 405 is transferred to the tilt connector 151 of the bucket 15 via the kinematic chain 406, thereby tilting the bucket 15. As all of the parts of the tilting arrangement 400, which may principally interfere with the front axle and/or front wheel 301 of the wheel loader, are located above the main arm 3, such an interference can be prevented. Thus, the tilting arrangement of the lifting arrangement according to the present embodiment does not restrain bucket roll back in any normal operating condition of the wheel loader, especially not in the lowered position.

[0068] As shown in FIG. 6, since the kinematic chain 406 comprises the tilting link 407 and the connecting link 408 pivotably connected to each other via a kinematic chain connector 411 it is possible to tilt the bucket 15 by retracting the tilting cylinder 410 in the lifted position. By retracting the tilting cylinder 410 in the lifted position the kinematic chain connector 411 moves upward away from the main arm 3 thereby avoiding collision of the kinematic chain 406 with the main 3.

Second Embodiment

[0069] FIGS. 7-8 illustrate a lifting arrangement according to a second embodiment. The lifting arrangement according to the second embodiment comprises a tilting arrangement 400 substantially according to the first embodiment, therefore only differences between these embodiments will be outlined in the following.

[0070] The tilting arrangement 400 according to the second embodiment is configured identically to the tilting arrangement of the first embodiment with the exception that the tilting cylinder 410 is not connected to the front frame portion 30 of the articulating steering arrangement, but to the main arm support means 6. This facilitates the mounting of the lifting arrangement to the front frame portion 30 of the wheel loader since the tilting cylinder 410 does not have to be connected thereto.

[0071] The lifting arrangement according to the second embodiment and lifting procedure thereof is now explained in detail under reference to FIGS. 9-12. Except for the differences outlined below, the lifting arrangement according to this second embodiment is configured as that of the first embodiment described above and therefore the explanations concerning the lifting procedure apply also to the first embodiment.

[0072] An auxiliary actuating element 21 embodied as linear actuator is provided in the lifting arrangement according to this second embodiment. The auxiliary actuating element 21 has a first end 21a and second end 21b, the first end 21a being pivotably mounted to said main arm support link 6a in the embodiment shown in FIG. 9. The second end 21b of the auxiliary actuating element 21 is pivotably mounted to said main arm 3. Accordingly, the auxiliary actuating element 21 operates in order to vary the angle of inclination between the main arm support link 6a and the main arm 3. In other words, by extending the auxiliary actuating element 21, the angle enclosed by the main arm support link 6a and the main arm 3 is increased.

[0073] By actuating the main arm actuating element 11, the main arm 3 is rotated about a pivot center provided at the second bearing portion 13 of said main arm support link 6a. In other words, by extending the main arm actuating element 21, the main arm 3 is rotated together with the main arm support link 6a in the clockwise direction such that a lifting operation is achieved.

[0074] Reference is made to FIG. 12, which discloses the elements of the control system used for the lifting arrangement according to this second embodiment of the invention.

[0075] The shown control system is only an example and elements which are not essential for the invention are not shown in this illustration. The control system shown in FIG. 12 is mounted in the construction machine at a suitable position. The basic element of the control system is a control means 60 which includes a CPU for performing control operations and other calculations which are required for operating the control system. Information can be obtained from a determining means 50 for determining a lifted related quantity reflecting a position of said equipment connector 5 with respect to the front frame arrangement 30. The determining means 50 can include sensors 51, 52, 51A, 52A. The sensors can be embodied as linear sensors 51, 52 which provide information on the extension position of the linear actuators used for the main arm actuating element 11 and the auxiliary actuating element 21. Such sensors are well known to the skilled person and will be suitably selected from available types. As alternative, rotation sensors can be mounted to those elements of the lifting arrangement which experience a relative rotation between two elements, such as at the connection between the pivot connector 4 of the main arm 3 and the first bearing portion 12 of the main arm support link 6a or at the bearing portion supporting the second bearing porting 13 of the main arm support link 6a on the front frame portion 30. The type of sensors can be selected as needed as long as it is possible to provide information on the relative position of the main arm with respect to the main arm support link 6a as well as the relative position of the main arm support link 6a with respect to the front frame portion 30. The determining means 50 using the above mentioned sensors transmits electric signals to the control means 60 which are further processed by the CPU as follows.

[0076] The CPU of the control means 60 communicates with a storage means 63 and is capable of obtaining information from the storage means and of transferring information to the storage means 63. The storage means 63 includes besides others information in the form of a set of data, such as functions or patterns.

[0077] Furthermore, an input section 61 communicates with the control means 60. The input section 61 is capable of transferring signals to the control means 60 which are e.g. triggered by the operator operating the construction machine. As alternative or in addition, the input section 61 can further communicate with additional control systems in order to provide an automatic trigger for transferring signals to the control means 60.

[0078] The control means 60 communicates with an output section 63 which is provided for controlling the actuating system of the lifting arrangement, in particular, the main arm actuating element 11 and the auxiliary actuating element 21. The output section 63 can be combined with a not illustrated solenoid section controlling pressures and/or flow rates of hydraulic fluid to and from the pressure chambers of the actuators in a known manner. Consequently, the output section 62 can transfer the signals provided from the control means 60 into actuating movements of the main arm actuating element 11 and the auxiliary actuating element 21.

[0079] The above indicated functions or patterns included in the storage means 63 is used for controlling the movement pattern of the equipment connector 5 of the lifting arrangement in the course of a lifting operation. According to the present embodiment, the control system provides a relationship between the movement of the main arm actuating element 11 and the movement of the auxiliary actuating element 21. In other words, the function or pattern included in the storage means 63 includes a relationship between the operating position of the main arm actuating element and the operating position of the auxiliary actuating element 21. The relationship can be continuous.

[0080] The operation of the control based lifting arrangement is explained in the following. Starting out from the situation in FIG. 9, the operator manipulates a not illustrated operating element which is associated with the input section 61 in order to initiate a lifting operation for lifting the equipment connector 5 from the lowered position shown in FIG. 9 to a lifted position shown in FIG. 11 through an intermediate position shown in FIG. 10. With the lifting arrangement shown in FIG. 9, the main arm actuating element 11 is extended in order to rotate the main arm 3 together with the main arm support link 6a in the clockwise direction in the drawing. In the course of the operation of the main arm actuating element 11, the auxiliary actuating element 21 is retracted as can be derived from a comparison of FIG. 9 with FIG. 10. Based on this retraction of the auxiliary actuating element 21, the angle enclosed between the main arm 3 and the main arm support link 6a is decreased and the pivot connector 4 is withdrawn in the rearward direction with respect to the frame arrangement.

[0081] Upon further performing the lifting operation from the intermediate position shown in FIG. 10, the main arm actuating element 11 is further extended in order to further rotate the main arm 3 in the clockwise direction in the drawing. In the course of the lifting operation between the intermediate position shown in FIG. 10 towards the lifted position shown in FIG. 11, the auxiliary actuating element 21 is again extended in order to increase the angle enclosed between the main arm 3 and the main arm support link 6a. By this, the pivot connector 4 moved in the forward direction with respect to the frame arrangement.

[0082] Based on the above cooperation of the main arm actuating element 11 and the auxiliary actuating element 21 in combination with the construction using the main arm support link 6a, a movement pattern of the equipment connector 5 can be provided which deviates from a circular path having a constant radius.

[0083] The above explained resulting movement pattern which can be derived from FIGS. 9-11, is achieved by using a closed loop control with signals from the sensors as input and signals from the output section 62 as output. Starting again out from the situation in FIG. 9, the determining means 50 using the sensors continuously determines the extension positions of the main arm actuating element 11 and the auxiliary actuating element 21 under the precondition that linear sensors are used. By initiating the lifting operation, the sensor determining the extension position of the main arm actuating element 11 senses a predetermined extension and transmits this as a signal to the control means 60. The control means uses this signal and compares the obtained signal continuously with a selected function or pattern present the storage means. The function can be provided as a continuous function defining the relationship between the extension position of the main arm actuating element 11 and the extension position of the auxiliary actuating element 21 such that this comparison will result in a unique output of a target extension position of the auxiliary actuating element 21. The output section 62 will control the solenoid section in order to set the auxiliary actuating element 21 to the position which corresponds to the target position obtained from the pattern in the storage means.

[0084] The above mentioned closed loop control is continuously performed by the control system such that there is always a unique relationship between the extension position of the main arm actuating element 11 and the extension position of the auxiliary actuation 20 element 21. According to the present embodiment, as stated above, the pattern or function can be set such that the movement pattern of the equipment connector can be predetermined in various ways.

[0085] Based on the above operation, the bucket 15 shown as example in FIG. 9 can be moved from the lowered position shown in FIG. 9 to the lifted position shown in FIG. 11 through the intermediate position shown in FIG. 10. Based on the control system and arrangement, the movement of the equipment connector 5 is controlled by the control system along a predetermined movement path which is shown as path P in the drawings. In the present illustration, the path P has an S-shape but basically follows a vertical path throughout the movement of the equipment connector from the lowered position to the lifted position. In particular, the path P deviates from a circular path which is achievable with prior art lifting arrangements in which the pivot connector 4 of the main arm 3 is immovably and stationary with respect to a frame portion of the construction machine 1 and the equipment connector 5 is stationary with respect to the main arm 3. According to the present embodiment, the movement of the pivot connector 4 of the main arm is achieved by providing the moveable main arm support means 6 and the auxiliary actuating element 21 in addition to the above discussed control system such that the main arm 3 is moved with a specified movement pattern such that a basically vertical movement range of the equipment connector 5 is achievable.

[0086] The lifting arrangement according to the second embodiment further comprises a tilting arrangement 400, which is not illustrated in FIGS. 9-11. The tilting arrangement 400 is configured according to the first or second embodiment of the tilting arrangement 400 described in connection with the lifting arrangement of the first embodiment.

Third Embodiment

[0087] The lifting arrangement according to the third embodiment is now explained in detail with reference to FIG. 13. FIG. 13 illustrates the lifting arrangement according to the third embodiment on a left side in a lowered position and on a right side in a lifted position.

[0088] Except for the differences outlined below, the lifting arrangement according to the third embodiment is configured as that of the first and second embodiment described above. Therefore, also the explanations concerning the lifting procedure made above (see second embodiment) apply also to the third embodiment.

[0089] The third embodiment differs from the second embodiment in that a short self-level link 412 and long self-level link 413 have been added. The short self-level link 412 is attached to the main arm support link 6, and to both the long self-level link 413 and the tilting cylinder 410. The long self-level link 413 is attached to the front frame 30, and to both the short self-level link 412 and the tilting cylinder 410.