TECHNICAL FIELD

This technology generally concerns track systems that are employed for guiding carriages between positions on a track and specifically concerns a track configured to guide and support moveable load carrying carriages thereon and including straight and curved track sections, a load carrying carriage to be supported on and moved along a track and a track system including such a track and carriage combination. BACKGROUND

Conveying track systems have been frequently used for transporting items of various kinds between different stations, such as loading and unloading stations where the items are to be handled. Such systems generally include an endless guide track with interconnected straight and curved track sections and carriages separately supported on and moved along the track. Conveying track systems including so-called linear drive systems have been on the market for some years and they employ individually controlled movable carriages called "movers". This linear type of drive system in essence consists of a number of such movable carriages or movers having magnets driven by magnetic fields from coils fitted to a fixed part of the system that is commonly named a motor module. The systems are constantly being de- veloped so as to include more and more types of motor modules, e.g. modules for 45° or 90° degree curves and modules for varying drive forces. To control movement of the carriages a mechanically linear support and guide system is required that keeps the magnets positioned above the coils and that may carry an external useful load. Based on an evaluation of a number of systems being presently available on the market it has been established that today the existing integrated mechanical support systems suffer from a number of weaknesses. In summary, such existing systems are above all configured for supporting lighter live or useful loads; the systems require lubrication in order to provide an acceptable service life; and since the carriages of the systems are designed to be propelled both in curves and along straight track sections, it has been necessary to make compromises in the configuration thereof, with the resulting reduction of the load carrying capacity.

The basic types of track systems that have been developed include overhead track systems with carriages that are supported on upper track surfaces and track systems with carriage support or bearing wheels engaging side surfaces of a track. The overhead type track system normally includes carriages having wheels engaging an upper as well as a lower track surface. It has the advantage that the carriage support wheels at all times make good contact with the track upper surface. Thus, the carriages are securely supported on the track since loads applied on the carriage assist in maintaining good contact between track and carriage support wheels. The overhead type track system therefore also allows for track configurations with height variations or curves in a vertical plane. On the other hand such systems may be unstable in a sideways direction and are less suited for coping with curves extending in a horizontal plane.

The track systems having carnage support or bearing wheels engaging track side surfaces will generally tend to cope better with track curves extending in a horizontal plane. However, in such track systems it will be difficult to maintain good contact between all bearing wheels and the track surfaces. In particular they will allow less weight to be applied on the carriages in order to maintain secure and stable guiding of the carriages on the track.

EP2617620A2 discloses a track system of the latter type with carriage side bearing wheels and proposes to improve track side and bearing wheel contact by varying the track width. SUMMARY

It is a general object to provide an improved solution to the above discussed problems.

In particular it is an object to suggest an improved track configured to guide load carrying carriages between positions thereon.

In particular it is another object to suggest an improved carriage configured to be supported on and move along a track.

In particular it is yet another object to suggest a track system including an improved track and carriage combination.

These and other objects are met by the technology as defined by the accompanying claims. The technology generally relates to a track system for transporting items of various kinds between different stations. The track system includes a track for supporting and guiding load carrying carriages between positions on the track. In a first aspect of the technology, there is provided a track for supporting and guiding load carrying carriages between positions on the track that includes straight and/or curved track sections. The track has inner and outer track sides with guide formations and guide surfaces for multiple stabilizing guide wheels of said load carrying carriages, a track top for cooperation with multiple load carrying wheels of said load carrying carriages. In a basic configu- ration the track top, extending lengthwise along the track has an upper surface with areas of varying height profile around the track. The track upper surface includes a first area having a high profile in curved track sections and a low profile in straight track sections and a second area having a low profile in curved track sections and a high profile in straight track sections. In accordance with another aspect of the technology there is provided a load carrying carriage configured to be supported on and to move along a track having straight and/or curved track sections, inner and outer track sides with guide formations and guide surfaces for multiple stabilizing carriage guide wheels and a track top for cooperation with upper load carrying wheels of said load carrying carriage. In a basic configuration the load carrying carriage has four load carrying wheels arranged at fixed locations in upper, front areas as well as in upper, rear areas of the load carrying carriage. The load carrying wheels are arranged at approximately the same height and one pair of front and rear load carrying wheels on a first side of the carriage are supported on shafts being perpendicular to a carriage longitudinal plane and another pair of front and rear load carrying wheels on a second side of the carriage are support- ed on shafts arranged at an angle other than perpendicular to the carriage longitudinal plane.

According to a further aspect of the technology there is provided an improved track system consisting of a track and at least one load carrying carriage. The track serves to support and guide the carriage between positions on the track that includes straight and/or curved sections and that has inner and outer track sides with guide formations and guide surfaces for multiple stabilizing guide wheels of said carriage. The track also has a track top for cooperation with multiple load carrying wheels of the load carrying carriage that is configured to be supported and guided along the track. In a basic configuration of the track system the track top, extend- ing lengthwise along the track, has an upper surface with a first area having a high profile in curved track sections and a low profile in straight track sections and a second area having a low profile in curved track sections and a high profile in straight track sections. The load carrying carriage has four load carrying wheels arranged at fixed locations in upper, front areas as well as in upper, rear areas of the load carrying carriage. The load carrying wheels are arranged at the same height and one pair of front and rear load carrying wheels on a first side of the carriage are supported on shafts being perpendicular to a longitudinal plane of the carriage and another pair of front and rear load carrying wheels on a second side of the carriage are supported on shafts arranged at an angle other than perpendicular to the longitudinal plane of the carriage.

Preferred further developments of the basic idea as well as embodiments thereof are specified in the dependent subclaims.

Advantages offered by this technology, in addition to those described above, will be readily appreciated upon reading the below detailed description of embodiments of the technology.

BRIEF DESCRIPTION OF THE DRAWINGS

The technology and its further objects and advantages will be best understood by reference to the following description taken together with the accompanying drawings, in which:

Fig. 1 is a very schematic illustration of a prior art track system;

Fig. 2A is a perspective view of an exemplary embodiment of a track system according to the presently suggested technology;

Fig. 2B is a top view of the track system of Fig. 2 A;

Fig. 3A illustrates a first cross-section through the exemplary embodiment of the track system, taken along line A- A in Fig. 2B;

Fig. 3B illustrates a second cross-section through the exemplary embodiment of the track system, taken along line B-B in Fig. 2B; Fig. 4A is a top view of a track included in the exemplary embodiment of the track system of Fig. 2A;

Fig. 4B is a first cross-section through the right half of the exemplary track of Fig. 4A, taken along line C-C in Fig. 4A;

Fig. 4C is a second cross-section through left and right halves of the exemplary track of

Fig. 4A, taken along line D-D in Fig. 4A;

Fig. 5 is an enlarged front end view of an embodiment of a carriage in the track system of

Fig. 2A, shown as supported on a straight track section shown schematically and in section;

Fig. 6 is a rear perspective view illustrating the carriage in the embodiment of Fig. 5;

Fig. 7 A is a bottom view of the carriage in the embodiment of Fig. 5;

Fig. 7B is a top view of the carriage embodiment of Fig. 5;

Fig. 7C is a rear end view of the carriage embodiment of Fig. 5; and

Fig. 7D is a side view of the carriage embodiment of Fig. 5.

DETAILED DESCRIPTION

The present technology will now be explained with reference to an exemplifying embodiment of a track system of this technology that includes a track and carriages and as illustrated in the accompanying drawing figures 2-7D. The illustrated embodiment of the track system with track and carriages relates to an application of the proposed technology to a product handling system for conveying products between loading and unloading stations that may be served by material/product handling robots. It is emphasized though, that the illustrations are for the sole purpose of describing preferred embodiments of the technology and are not intended to limit the presently proposed technology to details or to any specific field of application thereof. The presently proposed solutions may with only minor adaption be applied to most types of material and product handling and transport systems. It is also emphasized that the use throughout the specification and claims of the terms "track", "carriage" and "wheels" shall not limit the technology to any specific type of system or system configuration. Therefore, the term "carriage" shall include any type of moving device, the term "track" shall include any type of supporting structure on which such moving devices may be supported and guided and the term "wheels" shall include any type of means allowing a moving device to be supported and guided along a supporting structure irrespective of size or shape.

In the introductory part of the specification reference was made to a known type of track system having carriage support or bearing wheels engaging track side surfaces. Fig. 1 schematically illustrates one example of such a prior art track system 1 having a track 2 with curved and straight sections. In this system 1 efforts have been made to increase the stability of the carriages 3 moving along the track. An essential feature of this known system is that the carriages each have a single wheel 5 engaging an inner side of the track 2 and a pair of wheels 4 engaging an opposite side of the track. The track 2 has also been configured with a varying width between the two sides to maintain a better tolerance between the wheels and the sides of the track. The purpose thereof would be to try and reduce the play between the guide wheels 4, 5 engaging the sides of the track and said track side surfaces. As a result of such efforts it has been possible to increase the load capacity of the carriages to a certain degree. However, the stability and load carrying capacity of this prior art system is still far from adequate for many applications requiring a high load capacity.

To overcome the above described disadvantages and problems with the operation of known systems, the present technology now suggests a novel approach for optimizing overall system operation by enabling the system to carry greater useful load. In essence this is achieved by improving the support and stability of the carriages by suggesting a unique combination of wheel guide surfaces and formations at both sides of the track and areas with specifically configured wheel support surfaces at a track upper surface. This configuration provides several essential advantages that include:

A possibility to dimension the system for optional loads;

Enables the use of pre-lubricated ball bearings in the wheels, which essentially increases the useful life of the system A unique design of the support surfaces of the wheels secures that the ball bearings can carry the same high loads in both straight track sections and in curve sections;

Compared to existing systems the load carrying capacity of the support may be used to a maximum level.

An additional advantage is that the system that being based on the new technology optionally may be used in combination with existing drive systems available on the market or may be equipped with its own drive system. In Figs. 2A-3B is illustrated a first exemplary embodiment of the application of the proposed technology to a track system 11 configured specifically but not exclusively for conveying products between different positions/stations (not specifically shown) where robots may be located for loading and unloading products onto and from the track system, respectively. Fig. 2 A is a perspective view of the proposed track system 11 that includes a track 12 of rail-like design and load carrying carriages 25.1 and 25.2 supported on the track 12. In the figure the track system 11 is for convenience only shown having two load carrying carriages. It should be realized, though, that in practical applications the track system 11 could support any appropriate number of load carrying carriages, as is schematically indicated in Fig. 2B by a further carriage 25N.

The actual track 12 is configured to support and guide the load carrying carriages 25.1, 25.2, 25N between said positions on the track 12. The track 12 may be designed having a specific length but is normally endless, including a combination of interconnected straight track sections 12A and curved track sections 12B, as in the illustrated embodiment. It will be empha- sized, though, that the track 12 may in other applications also consist only of a number of curved sections with different radiuses of curvature. The track may further be manufactured as one integral structure or may consist of a number of assembled and interconnected track parts of varying length. In the shown embodiment the track consists of the above mentioned straight and curved sections 12 A, 12B that are appropriately fixed to each other such as by means of suitable, but not specifically illustrated attachments 10 (Fig. 2 A). The track 12, or sections thereof, such as curved sections 12B, may be integrated with or fixed to a base plate 15 providing additional support as well as accommodating fasteners 16 for securing the track 12 to a foundation or frame (not shown). As illustrated especially in Figs. 3 A and 4B the track 12 or sections thereof may be supported on individually adjustable supports/spacers 17. The track system 1 1 of this technology also has a drive arrangement for moving the load carrying carriages 25.1, 25.2, 25.N along the track 12. An example of such a drive arrangement 40 is illustrated very schematically in Fig. 2B and consists of an inner, substantially parallel track 41 with movers or driver units 42 that in turn each have a link 43 fixed to one each of the carriages 25.1, 25.2, 25. N. To increase drive power several such movers may be linked to each carriage of the track system 11. This parallel drive track 41 may be based on the above mentioned prior art drive system where the movers are driven by magnetic fields from coils of a motor module. Optionally, the track system may include a drive arrangement based on the known principles of belt-drive or rack-and-pinion-drive.

With reference specifically also to Figs. 3A and 4A-4C the rail-like track 12 has inner 21 and outer 20 track sides with guide formations 18, 19A, 19B and 19C and guide surfaces 23, 24 for multiple stabilizing guide wheels 27, 28 of said load carrying carriages 25.1, 25.2, 25N, as will be described in greater detail below. The track 12 also has a track top 22 for cooperation with multiple load carrying wheels 26 of each load carrying carriage 25.1, 25.2, 25N that is configured to be supported on and guided along the track 12. Extending lengthwise, i.e. longitudinally along the track, the track top 22 has an upper surface 13, 14 with areas of varying height profile around the track; a first area 13 with a high profile in curved track sections 12B and a low profile in straight track sections 12 A; and a second area 14 with a low profile in curved track sections 12B and a high profile in straight track sections 12 A. With the overall configuration of the illustrated embodiment the first area 13 of the track upper surface is an outer area of the track top 22 and the second area 14 of the track upper surface is an inner area of the track top 22.

The transitions from high to low profiles of the respective first 13 and second 14 track top areas are provided approximately at entrance and exit portions 12C and 2D, respectively between curved 12B and straight 12A track sections. These transitions of the respective first and second track top areas 13, 14 between the high and low profiles overlap slightly at said entrance 12C and exit portions 12D between the curved 12B and straight 12A track sections. In other words, the high profiles of the first 13 and second 14 track top areas run in parallel for a slight distance at said entrance and exit portions. This configuration will contribute to the stable movement of the carriages 25.1, 25.2, 25N with their load carrying wheels 26 supported on said track top 22 around the track 12, as will be further explained below.

As was mentioned above, the track sides 21, 20 are provided with guide formations and guide surfaces. Specifically, a first guide formation in the shape of a lock groove 18 is formed in an outer side 20 of the track and is configured for holding and guiding a number of, in this embodiment two, below described carriage locking wheels 28.1, 28.2. This lock groove extends along the full extension of the track 12 outer side 20. Furthermore, a central guide formation in the shape of an inner recess 19A is formed at least in the area of an exit portion 12D of the inner track side 21 of the curved track sections 12B. The inner recess 19A has a largest depth in a radial direction of the track 12 in the area of the exit portion 12D but preferably extends with a smaller radial depth all around the curved section 12B. In most applications the central inner recess 19A does also extend a limited distance into the adjoining straight section 12 A, past the transition between the curved and straight sections. This inner recess 19A is configured for guiding a number of first inner radial carriage stabilizing wheels 27.1.1, 27.1.2 at said exit portion 12D.

Further guide formations are provided in the shape of upper and lower, inner recesses 19B, 19C that are formed at least in the area of an entrance portion 12C of the inner track side 21 of the curved track sections 12B, as will be seen especially in the left side of the cross-section of Figs. 3B and 4C. The upper and lower, inner recesses 19B, 19C likewise have a largest depth in a radial direction of the track 12 in the area of the entrance portion 12C but preferably extend with a smaller radial depth all around the curved section 12B. In most applications the upper and lower inner recesses 19B, 19C also extend a limited distance into the adjoining straight section 12A, from a position just before the entrance portion 12C and past the transition between the curved and straight sections. In this case the recesses 19B, 19C are configured for guiding a number of second inner radial carriage stabilizing wheels 27.1.3, 27.1.4 at said entrance portion 12C and through the curved section 12B. The entrance 12C and exit 12D portions of the curved track sections 12B thereby relate to a travel direction TD of the carriages 25, 25.1 , 25.2, 25. N on the track 12, as indicated in Fig. 2B, but it should be emphasized that the same functionality will be obtained if the travel direction is reversed. With the identical carriages the only difference would be a change of terms where the entrance portions would be the exit portions etc. Inner and outer guide surfaces 23, 24 are further formed by inner and outer track sides 21 , 20, respectively, and configured for guiding the number of first and second inner radial carriage stabilizing wheels 27.1.1 , 27.1.2, 27.1.3, 27.1.4 around the inner track side 21, essentially outside the curved sections 12B and said recesses 19A, 19B, 19C_and for guiding later de- scribed, outer radial carriage stabilizing wheels 27.2.1, 27.2.2, 27.2.3, 27.2.4 around the full length of the outer track side 20, outside of the lock groove 18.

With specific reference to Figs. 5-7D the load carrying carriages 25.1, 25.2, 25N of the track system 1 1 will now be further explained as will their cooperation with the system track 12. Each carriage is here represented by the load carrying carriage, 25.2 of Fig. 2B and has four load carrying wheels 26.1.1, 26.1.2, 26.2.1, 26.2.2 provided at fixed locations in upper, front areas as well as in upper, rear areas of the load carrying carriage 25.2. The load carrying wheels 26.1.1, 26.1.2, 26.2.1, 26.2.2 are all arranged at the same height. This means that a load carrying outer circumference OC of all load carrying wheels is arranged at approxi- mately the same height and is set to engage and roll on a common plane that in practice is a horizontal plane in which all high profiles of the track areas 13, 14 lie.

Specifically, one first pair of front and rear load carrying wheels 26.1.1, 26.1.2 are provided on a same, first side of the load carrying carriage 25.2. This first side is the left side of a central longitudinal plane LP through the load carrying carriage 25.2 when viewed from the front end of the load carrying carriage 25.2, against the direction of travel TD as specified in Fig. 2B. In this case, the left side load carrying wheels 26.1.1, 26.1.2 are supported on shafts 29.1, 29.2 being perpendicular to the longitudinal plane LP of the load carrying carriage 25.2. Another second pair of front and rear load carrying wheels 26.2.1 , 26.2.2 are provided on a same, second side of the load carrying carriage 25.2. In consequence with the above, this second side is the right side of the longitudinal plane LP through the load carrying carriage 25.2 when viewed from the front end of the load carrying carriage 25.2, against the direction of travel TD. The right side load carrying wheels 26.2.1, 26.2.2 are supported on shafts 30.1, 30.2 arranged at an angle other than perpendicular to the longitudinal plane LP of the carriage 25.2. The angle of the shafts 30.1, 30.2 of the second pair of front and rear load carrying wheels 26.2.1, 26.2.2 to the longitudinal plane LP of the carriage is calculated based on a radius of curvature of the curved track sections 12B. Each load carrying carriage 25.2 has inner and outer side wall sections 31, 32 configured for straddling the track 12 of the track system 11 and at least one pair of front and rear carnage locking wheels 28.1 , 28.2 journalled in an outer side wall section 32. Again, it shall be realized that the expressions "front" and "rear" relate to the travel direction TD of the carriage 25.2 on the track 12. Said carriage locking wheels 28.1, 28.2 are configured for engaging and cooperating with the wheel lock groove 18 formed in the outer track side 20 in order to stabilize and lock the carriage 25.2 in position.

Each load carrying carriage 25.2 has a number of, at least a pair of, first inner, upper and lower guide wheels 27.1.1 , 27.1.2. Related to a travel direction TD of the load carrying carriages 25.2 on the track 12 said first carriage stabilizing guide wheels are named front guide wheels 27.1.1, 27.1.2. These first inner guide wheels 27.1.1, 27.1.2 are journalled in an inner side wall section 31 of the load carrying carriage 25.2. They are configured for constantly engaging the inner track side 21. Specifically, this constant engagement takes place so that the first inner guide wheels 27.1.1, 27.1.2 alternatingly engage the inner guide surface 23 of the inner track side 21 or are guided by the central inner guide recess 19A formed at an exit portion 12D and in the curved track sections 12B of the track 12. Each load carrying carriage 25.2 also has number of, at least a pair of, second inner, upper and lower carriage stabilizing guide wheels 27.1.3, 27.1.4. Again related to the travel direction TD of the load carrying carriages on the track 12 said second carriage stabilizing guide wheels are named rear guide wheels 27.1.3, 27.1.4. They are in this case configured for constantly engaging the inner track side 21. Specifically, this constant engagement takes place so that the first inner guide wheels 27.1.3, 27.1.4 alternatingly engage the inner guide surface 23 of the inner track side 21 or are guided by the upper and lower inner recesses 19B, 19C formed at the entrance portions 12C of the inner track side 21 and in the curved track sections 12B.

A number of, at least two pairs of, outer, front and rear, upper and lower radial carriage stabilizing guide wheels 27.2.1, 27.2.2, 27.2.3, 27.2.4 are also provided and configured and arranged to engage and be guided on the outer guide surface 24 formed along a full length of the outer track side 20 to stabilize the load carrying carriages 25.1 , 25.2, 25 in position. They are journalled in the outer side wall sections 32 of the load carrying carriages. As is clear from the above, the four load carrying wheels 26.1.1 , 26.1.2, 26.2.1 , 26.2.2 are configured for being supported on the track top 22 and assist greatly in stabilizing the travel of the load carrying carriages, especially at the transitions between curved and straight sections of the track. As a result of the different angles of the load carrying wheels in combination with the different levels or height profiles of the track areas engaged by said load carrying wheels in straight and curved track sections the travel of the carriages along the entire track extension will be stable and free from play. This in turn reduces the risk of incorrect positioning, vibration and mechanical overloads. By loading different wheels in the different track sections and areas, wear may be reduced. Thus, a stable and uniform carriage operation may be guaranteed for a rigid carriage since the fixed load carrying wheels have a different angular alignment in order to secure that they roll on a radius in the curved track sections and are longitudinally aligned in straight track sections.

Each load carrying carriage also has several carriage stabilizing wheels that serve to stabilize the carriage position in a radial direction, in straight track sections as well as in curved track sections. In the exemplary embodiment the outer radius of the track 12 in the curved sections 12B is constant and serves as the base for the positioning and guiding of the load carrying carriages by means of the outer stabilizing guide wheels around the curved track sections and in the transition areas between curved and straight sections. All deviations of the load carrying carriages will therefore be compensated for by the provision of the guide recesses 19A, 19B, 19C at the track 12 inner side 21. However, in other embodiments of the technology it is likewise possible to maintain a centre of the carriages on a constant radius and to configure both the outer and the inner sides of the track with guide formations having curved profiles. The extension of the inner central 9 A, upper 19B and lower 19C guide recesses along the inner track side 21 as well as a depth thereof is calculated based on the dimensions of the curved sections 12B. With the illustrated configuration of the load carrying carriages the extension and positioning of said recesses is not related to a travel direction TD of the load carrying carriages on the track, so that said carriages may travel on said track in a clockwise as well as a counterclockwise direction.

In total there are fourteen wheels provided for stabilizing each load carrying carriage of the illustrated embodiment. Four wheels are supported on the track top, four wheels engage the inner track side radially, four further wheels engage the outer track side radially, and two locking wheels engage the lock groove on the outer track side. The above described configuration of the guide recesses that may be milled from the track side, secures that the radial carriage stabilizing guide wheels never loose contact with the surface that they roll on. This great number of guide wheels assists further in providing stability and serve the different mentioned purposes in straight and curved track sections. Not least do they serve to maintain an exact carriage positioning, to secure a high load capacity and to provide less track wear.

The present technology has been described in connection with embodiments that are to be regarded as illustrative examples thereof. It will be understood by those skilled in the art that the present technology is not limited to the disclosed embodiments but is intended to cover various modifications and equivalent arrangements. The present technology likewise covers any feasible combination of features described and illustrated herein. The scope of the present technology is defined by the appended claims.