Front frame arrangement for a working machine and a wheel loader

TECHNICAL FIELD

The present invention relates to a front frame arrangement for a working machine, for supporting a pair of front wheels. The invention also relates to a wheel loader comprising a front frame arrangement as mentioned above.

BACKGROUND ART

A working machine is provided with a bucket, container or other type of implement for lifting, carrying and/or transporting a load. A working machine may be operated with large and heavy loads in areas where there are no roads, for example for transports in connection with road or tunnel building, sand pits, mines and similar environments.

A working machine in the form of a wheel loader is also usually provided with a prime mover, such as an internal combustion engine, a transmission line, and a gearbox for supplying torque to the driving wheels of the wheel loader. In addition to supplying torque to the driving wheels, the internal combustion engine has to supply energy to one or more hydraulic pumps of a hydraulic system of the wheel loader. Such a hydraulic system is used for lifting operations and/or steering the wheel loader.

Hydraulic working cylinders are arranged for lifting and lowering a lifting arm unit, on which a bucket or other type of implement, attachment or working tool, for example forks, is mounted. By use of another hydraulic working cylinder, an implement such as a bucket can also be tilted or pivoted. Furthermore, hydraulic cylinders known as steering cylinders are arranged to turn the wheel loader by means of relative movement of a front body part and a rear body part of the wheel loader.

Furthermore, a traditional wheel loader comprises a front body part with a rigid front axle which is mounted to a front frame arrangement and which is adapted for supporting the two front wheels of the wheel loader. The front axle normally consists of a cast or welded housing having rotating internals and being bolted to the front frame. The front frame arrangement is normally arranged to support a lift

arrangement with a lifting arm and an implement, as mentioned above.

The front frame, the wheel axle and the lifting arm are designed to fulfil requirements regarding a specified loading capacity, flexibility of the lift arrangement, visibility and ease of operation for the driver and other operation parameters.

It is previously known to provide a wheel loader with individual hub motors, i.e.

separate hub motors arranged in each wheel. In this manner, torque can be supplied to each one of the driving wheels by means of the hub motors. The patent document US 2009/272596 teaches a wheel end assembly for a working machine which comprises a wheel hub support housing and a wheel hub drive assembly which is rotatably connected to the wheel hub support housing. The document also teaches that a hydraulic motor and wheel hub drive can be integrated into a single unit. The assembly according to US 2009/272596 solves a problem regarding the need for a reduced weight and improved steering control through the use of individual hub motors.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a front frame arrangement which enables improvements regarding weight, flexibility and/or operation of the lifting arrangement for a working machine such as a wheel loader.

In accordance with the invention, this is obtained by means of a front frame arrangement for a working machine, for supporting a pair of front wheels, which is characterized in that said front frame arrangement comprises a first arm and a second arm which are arranged at a predetermined distance from each other, each of the first arm and the second arm having a main extension direction intended to be substantially in parallel to the longitudinal direction of a working machine, thereby creating a space between the first arm and the second arm for accommodating at least a portion of a lift arrangement of a working machine in said space, each of the first and second arms having a means for individual suspension of a front wheel. The fact that the front frame arrangement according to the invention comprises individual suspension of a front wheel for each of said arms, and also that the invention lacks the traditional front axle connecting the front wheels, means that the above-mentioned space can be created. According to the invention, the space is adapted for accommodating the lift arrangement, at least partly. To this end, and according to an embodiment, the space between the arms is suitably positioned at a position generally between the front wheels. Furthermore, said means for suspension comprises a hub motor for driving each front wheel, said hub motor preferably being an electric motor

By means of the front frame arrangement according to the invention, certain advantages can be obtained. Firstly, the arrangement leads to a reduced weight of the working machine. In particular, the combined weight of a front frame with integrated hub motors can be reduced as compared with the weight of a traditional front axle and front frame.

According to an embodiment, the front frame arrangement is adapted to support a lift arrangement comprising an implement and a lifting arm. Due to the fact that said space is created, a more flexible and effective use of the available space between the arms is provided during operation of the lift arrangement. In particular, the invention allows the lifting arrangement to be lowered and positioned between the arms. This means that the handling of an implement such as a bucket can be improved. For example, the linkage and working load can be displaced closer to the front wheels which improves tipping load and machine performance. Furthermore, the invention leads to improved visibility.

Furthermore, the front frame arrangement according to the invention is suitably arranged for pivotally supporting the lifting arm. In this manner, the lifting arm can be arranged to pivot about a substantially horizontal axis extending generally transverse to the longitudinal direction of the working machine. The pivoting support of the lifting arm is preferably obtained by arranging the lifting arm pivotally in the first and second arms. Also, the first arm and a second arm are suitably shaped as closed, generally boxlike structures, generally having a triangular form with sufficient strength and stiffness, wherein an upper, rear corner of such a triangle defines a support point for the lifting arm. Furthermore, a lower, front corner of such a triangle suitably defines a support for each one of the front wheels. Also, the lower part of each arm is suitably connected by means of a connecting element.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be described below with reference to the enclosed drawings, which:

Fig. 1 is a perspective view of a working machine having a front frame arrangement according to the invention; Fig. 2 is a schematic perspective view showing certain parts of the front frame arrangement; and

Fig. 3 is a perspective view of a cut-out part of a front frame arrangement according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

The invention will now be described initially with reference to Fig. 1 , which is a perspective view of a working machine 1 in which the present invention can be implemented.

According to the shown embodiment, the invention is implemented in a working machine 1 in the form of a wheel loader which is intended for use in construction work, road and tunnel building and similar situations. The wheel loader 1 comprises a rear body part 2 and a front body part 3. The rear body part 2 comprises for example an engine compartment with a combustion engine, a gearbox etc. (not shown in Fig. 1), and also a driver ^' s compartment.

The front body part 3 comprises a front frame arrangement 4 which is arranged for supporting a pair of front wheels 5, 6. The front frame arrangement 4 according to the invention will be described in greater detail below. Also, the rear body part 2 is arranged for supporting a pair of rear wheels 7, 8.

These parts of the wheel loader 1 are designed generally according to known technology, and for this reason they are not described in detail here. According to an embodiment, the combustion engine and gearbox are used for operating the rear wheels 7, 8 of the wheel loader 1. In a manner which is known as such, the combustion engine can also be used for operating electric and/or hydraulic devices, which for example can be used to operate lifting arrangements and similar in the wheel loader 1.

The front frame arrangement 4 comprises a first arm 9 and a second arm 10. In the context of the invention, the term "arm" is intended to describe a relatively thin and flat component which extends substantially along the longitudinal direction of the wheel loader 1. Each one of the first arm 9 and the second arm 10 can preferably be formed as a generally closed, box-like structure. The arms are positioned at a predetermined distance from each other. The distance is indicated by means of the letter "d" in Fig. 1. In the example embodiment, the first arm 9 and the second arm 10 are oriented with a generally flat side of each box-like structure facing towards each other.

Furthermore, each one of the first arm 9 and the second arm 10 extends along a main direction which is substantially parallel to the longitudinal direction of the wheel loader 1. The arms 9, 10 are preferably parallel to each other but the invention is not limited to such an arrangement only, i.e. the arms 9, 10 can be arranged in a slightly non-parallel manner without departing from the scope of the invention.

As shown in Fig. 1 , the wheel loader 1 is provided with a lift arrangement, which in turn comprises a lifting arm 11 and an implement 12, wherein the implement 12 suitably is in the form of a load-carrying bucket, as shown in Fig. 1. However, the invention is not limited to such an implement only but can be realized with other types of implements such as other load-carrying devices or working tools. Each one of the first arm 9 and the second arm 10 is provided with means for suspension of said front wheels 5, 6. The embodiment shown has means for suspension comprising a hub motor 13, 14 for each wheel 5, 6. The hub motors 13, 14 are positioned inside the front wheels 5, 6 as indicated in a schematic manner in Fig. 1. Furthermore, the hub motors 13, 14 are preferably of electric type. In a similar manner, two further hub motors 15, 16 can be arranged for the two rear wheels 7, 8. In this way, four hub motors 13, 14, 15, 16 provide independent traction of each wheel 5, 6, 7, 8 of the wheel loader 1. Fig. 2 is a simplified perspective view of certain parts of the front frame arrangement 4 according to the invention. Due to the fact that the first arm 9 and the second arm

10 are arranged along the longitudinal direction 17 of the wheel loader 1 , at a predetermined distance d, a space 18 is created between the first arm 9 and the second arm 10. The intention with this space 18 is to accommodate at least a portion of the lift arrangement, i.e. at least a portion of the lifting arm 11 and/or the implement 12.

In contrast to prior art technology, the invention relies on the principle that the lift arrangement can be at least partly positioned within the space 8. For example, the lifting arm 11 can be positioned in a lowermost position in which it extends through the space 18 (as shown in Fig. 1). In other words, a substantial part of the lifting arm

11 is positioned between the two front wheels 5, 6. This leads to certain advantages. Firstly, it should be noted that the lifting arm 11 and implement 12 can be made lighter and the visibility during operation of the wheel loader 1 can be improved. Also, the lifting arm 11 and implement 12 can be moved closer to the front wheels 5, 6, which improves tipping load and machine performance. The combination of the front frame arrangement 4 and integral hub motors 13, 14 also saves weight and energy for the complete wheel loader 1. With reference to Fig. 3, which is a perspective view of a cut-out section of an embodiment of the front frame arrangement according to the invention, there is shown that the arms 9, 10 (of which only the first arm 9 is visible in Fig. 3) are generally shaped as box-like structures having a triangular shape. Also, the lifting arm 11 is preferably pivotally arranged in the first and second arms 9, 10. More precisely, an upper, rear corner of each of said triangular structures formed by the arms 9, 10 constitutes a support point for the lifting arm 11 so that said lifting arm 11 can be pivoted about an geometrical horizontal axis 19. Preferably, the lifting arm 1 is arranged in the first and second arms 9, 10 in a manner so that it can be pivoted about the substantially horizontal axis 19 which extends substantially transverse to the longitudinal direction of the wheel loader 1.

Furthermore, a lower corner of each of said triangular structure - which is situated at the front of each arm 9, 10 - constitutes a support for each of the front wheels 5, 6 with their hub motors 13, 14.

As mentioned above, the first arm 9 and the second arm 10 can be designed as closed, generally box-like structures. The geometry and material properties of the arms 9, 10 are chosen in order to obtain the necessary stiffness and strength of the arms 9, 10. As particularly indicated in Fig. 3, the front frame arrangement 4 according to the embodiment can comprise a bottom component 20 which serves as a connecting element connecting the lower parts of the first arm 9 and the second arm 10 to each other. In this manner, the complete front frame arrangement 4 can be given the desired stiffness and strength.

Furthermore, the front frame arrangement 4 suitably comprises a rear component 21 which also contributes to connecting the first arm 9 and the second arm 10 with each other. According to one embodiment, the rear component 21 can be provided with a coupling unit, such as an upper pivot bracket 22 and a lower pivot bracket 23, for connecting the front body part 3 (cf. Fig. 1) to the rear body part 2 in a pivoting manner. Due to this arrangement, there is provided a front frame arrangement 4 which - in addition to creating a space 18 between the first arm 9 and the second arm 10 for accommodating the lift arrangement 11 - also serves as a coupling unit for connecting the rear body part 2 and the front body part 3 to each other.

The invention is not limited to the embodiment described above, but can be varied within the scope of the appended claims.