Technical field

The present invention relates to a drawbar configured to improve maneuverability of a trailer equipped with the drawbar.

Background

Trucks are often used to transport goods and are commonly used for towing trailers in order to improve the loading capabilities. Trucks with attached trailers constitute a relatively long vehicle affecting its maneuverability and turning radius. Accordingly, there is a demand of improved maneuverability of trucks and their attached trailers, especially to improve their maneuverability on roads which are difficult to access due to for example buildings or other structures arranged close to the road that may obstruct movement of the truck and its attached trailer. In order to achieve a certain turning radius for the truck and the trailer, towbars of different lengths have often been implemented.

Another approach is to use drawbar having an adjustable length in order to improve the maneuverability and to achieve an adjustable setting. An example of a drawbar with adjustable length is presented in WO 12/153005, where the drawbar has an adjustable length in order to create a versatile arrangement in connection with the drawbar of a trailer which will permit a truck to be reversed to couple a trailer.

Yet another approach to improve the maneuverability is to implement a drawbar being pivotably attached to the trailer. An example of a drawbar being pivotably attached to a trailer is presented in EP 0869896.

Despite the improvements within prior art there is still room for an improved drawbar for a trailer in order to achieve an improved maneuverability.

Summary of the invention

It is an object of the present inventive concept to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in combination. In particular, it may be desirable to provide an improved control of a truck and attached trailer. According to a first aspect of the inventive concept, these and other objects are achieved in full, or at least in part, by a drawbar arrangement comprising a base portion configured to be fixedly mounted to a wheelset of a trailer, a drawbar having a first end configured to be coupled to a coupling device of a towing vehicle, and a second end being pivotably connected to the base portion around a vertical pivoting axis, at least one actuator arranged to pivot the base portion with respect to the drawbar, the actuator having a first end attached to the base portion and a second end attached to the drawbar. In use, when the base portion is mounted to a wheelset of a trailer and the drawbar is coupled to a coupling device of a towing vehicle, the actuator is operable to pivot the base portion with respect to the drawbar so as to rotate the wheelset around a vertical axis.

When the pivotable drawbar arrangement of the invention is mounted on a trailer and connected to a towing vehicle, the actuator in effect allows turning the wheelset of the trailer, thereby offering superior maneuverability of the trailer. With a conventional (rigid) drawbar, the rotational angle of the wheelset is determined by the angle of the drawbar (i.e. the position of the towing vehicle). With the present invention, the rotational angle of the wheelset can be controlled independently of the drawbar angle (with limits determined by the design).

The wheelset may be a front wheelset of a so-called full trailer, in which case the wheelset is rotatable around a vertical axis with respect to the trailer frame. In this case, the base portion may be directly attached to the wheelset. Alternatively, the trailer has at least one centrally located wheelset which is fixed with respect to the trailer frame, and the entire trailer rotates with the wheelset(s). Such a trailer is referred to as a “central axle trailer”. In this case, the base portion may be attached to the wheelset indirectly, by being attached to the frame of the trailer.

The base portion may comprise two fittings configured to be attached to the trailer.

The drawbar arrangement may further comprise two actuators, one on each side of the drawbar. Two actuators allow a greater force to be exerted on the base portion. The first end of each actuator may further be attached to a fixation point on the base portion such that the fittings are located between the two fixation points. This means that the fixation points of the actuators are located further away from the vertical pivoting axis, thereby increasing the torque exerted by the actuators. The placement of the fixation points further away from the center of the trailer also allows for longer actuators. In the case of hydraulic actuators, which is a typical choice, a longer hydraulic cylinder can be more powerful than a short.

The drawbar arrangement may further comprise a locking mechanism for fixating the rotational position of the base portion with respect to the drawbar. Such fixation may be appropriate, or even required, for safety reasons when drawbar arrangement is used on a trailer towed on a public road at high speeds.

In one example embodiment, the locking mechanism includes a locking member arranged in a slot formed in the drawbar so as to be movable in a longitudinal direction of the drawbar between an open position and a locked position, and an opening in the base portion, which opening is configured to receive the locking member when the locking member is in the locked position, thereby preventing pivoting of the base portion with respect to the drawbar.

Brief description of the drawings

These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing currently preferred embodiments of the invention.

Fig. 1 a is a perspective view of a drawbar arrangement according to an embodiment of the present invention mounted to a full trailer.

Fig. 1 b is a schematic top view of the trailer in figure 1 a connected to a towing vehicle by means of the drawbar.

Fig. 2a is a perspective view of a drawbar arrangement according to an embodiment of the present invention mounted to a central axle trailer.

Fig. 2b is a schematic top view of the trailer in figure 2a connected to a towing vehicle by means of the drawbar.

Figs. 3a - 3b are schematic perspective views of the drawbar arrangement in figure 1 .

Fig. 4a - 4b are schematic perspective view of a drawbar arrangement according to another embodiment of the present invention. Fig. 5 is a schematic perspective view of a drawbar arrangement according to another embodiment of the present invention.

Fig. 6 is a top view of a drawbar arrangement attached to a trailer and connected to a truck according to an embodiment of the present invention.

Fig. 7 is a flowchart of a method for controlling a drawbar arrangement according to at least one embodiment of the present invention.

Detailed description of the invention

Fig. 1 a - 1 b illustrates a trailer 2. The trailer may be substantially elongated extending between a front and an aft side. Further, the trailer has a main towing direction, i.e. a direction resulting from towing the trailer in a forward direction.

The illustrated trailer 2 has a frame 3 supporting a cargo unit, here an open cargo unit. However, it should be understood that the cargo unit may be any type of unit arranged to transport goods and wherein the cargo unit is selected depending on the goods to be transported. The frame has a fixed rear wheelset 4 and a front wheelset 5. The front wheelset of the trailer 2 is configured to rotate about a vertical axis, A1 , to facilitate controlling the towing of the trailer 2.

A drawbar arrangement 1 is mounted to the front wheelset 5 of the trailer 2. The drawbar arrangement 1 comprises a base portion 6 mounted to the wheelset 5, a drawbar 8 pivotably attached to the base portion 6, and at least one actuator 7. Accordingly, the drawbar 8 is pivotable in substantially a sideways direction (in a horizontal plane) with respect to base portion 6 around a vertical axis B. The actuator(s) may be a linear actuator, a circular actuator, or any type of actuator suitable to control the pivot lateral and or pivoting position of the drawbar with respect to the base portion.

The drawbar 8 comprises a towing eye 9 for coupling to a coupling device 10 of a towing vehicle 11 , such as a truck or an intermediate trailer. When the base portion 6 is mounted to the rotatable wheelset 5 and the drawbar is coupled to the towing vehicle 11 , the actuator 7 is capable of rotating the wheelset 5 around axis A1 with respect to the longitudinal direction of the drawbar 8.

When the trailer 2 is coupled to a towing vehicle, the drawbar 8 will be fixed to the coupling device 10 of the towing vehicle. The actuator 7 may then rotate the front wheelset 5 about the vertical axis, A1 , such that the front wheelset 5 is set in a desired direction (different than the longitudinal axis of the drawbar), which may facilitate the maneuvering of the trailer 2 when being towed.

Fig.2a-b illustrates the drawbar arrangement 1 attached to a central axle trailer 12, having a frame 13 and a front wheelset 15 and a rear wheelset 14 arranged relatively close to each other. In this case, the wheelsets are not rotatable, i.e. the wheelsets 14, 15 of the trailer 12 are fixed in the main direction of travel.

The drawbar arrangement 1 in Fig. 2a may be identical to the drawbar arrangement in Fig 1a but the base portion 6 is here attached to the frame 13

With reference to figure 2b, the towing eye 9 of drawbar 8 is again connected to the coupling device 10 of a towing vehicle 11 . When the base portion 6 is mounted to the frame 13 and the drawbar 8 is coupled to the towing vehicle 11 , the actuator 7 is capable of rotating the entire trailer 12 around axis A2 with respect to the longitudinal direction of the drawbar 8. As is clear form figure 2b, the drawbar arrangement 1 allows backing up without bringing the trailer out of its course.

It should further be understood that the trailers 2,12 in Figs 1a-b and 2a-b may comprise more than two wheelsets, i.e. additional wheelset(s) (not shown).

Figure 2c shows another example of a drawbar arrangement 1 applied on a central axle trailer 12. As shown in figure 2c, the base portion 6 is mounted to the frame 13 a distance in under the body of the trailer, in order to be mounted closer to the wheel set 15. Such mounting will be beneficial when maneuvering, as the forces required to turn the trailer 12 will be smaller.

With reference to Figs. 3a - 3b the drawbar arrangement 1 in Figs. 1a -1b and 2a - 2b will now be discussed. As mentioned above, the drawbar arrangement 1 comprises a base portion 6 and a drawbar 8, pivotable with respect to each other around an axis B by means of (in this case) two actuators 7. It is noted that it may be sufficient with one single actuator (on one side of the pivoting point 23). The drawbar 8 is attached to the base portion 6 in a pivoting point 23. Outer ends 7a of the two actuators 7 are attached in two fixation points 24, formed in the base portion 6, while the inner ends 7b of the actuators are attached to the drawbar, a distance in front of the pivoting point 23, in two fixation points 25. Operation of the actuators 7 will thus turn the base portion 6 and the drawbar 8 with respect to each other around the pivoting point 23. It is noted that the relatively short distance between the axis B and the fixation points 25 allows a relatively angular displacement of the drawbar 8.

In the illustrated case, the base portion is formed by two plates 22, and the pivoting point 23 and the outer actuator fixation points 24 are formed between these plates 22. In a similar manner, fixation points 25 are formed between two plates 26 mounted to the upper and bottom sides of the drawbar 8.

Two fittings 27 are provided on the base portion 6, for attaching the base portion 6 to the wheelset 5 (fig 1a-b) or the trailer frame 13 (fig 2a-b). The fittings 27 are here located closer to a center axis of the base portion than the fixation points 24 (i.e. between the fixation points 24). It is noted that the distance between the two fittings 27 is typically determined by a standard regulated distance between drawbar attachment points on the trailer 2 (i.e. on the wheelset 5 or the frame 13). By providing fixation points 24 outside the fittings 27 (i.e. further away from the center axis of the base portion 6) the actuators 7 may be longer and thus more powerful. Also, with such a design a larger part of the force of the actuators acts in a direction tangential to the rotation axis B, thereby subjecting the base portion 6 (and thus the wheelset 5, 15) to a greater torque. The fittings 27 are here configured to allow a pivoting motion around a substantially horizontal axis C of the base portion 6.

The drawbar arrangement further comprises a control unit 30 connected to operate the actuators 7 in synchrony. The control unit 30 may be configured to control the actuators 7 based on user input from a user interface 31 , or based on a control signal from processing circuitry 32, programmed to determine a desired rotational angle of the wheelset 5 based on sensor input from one or several sensors 33, given appropriate programming of the control unit 27.

With reference to figure 4a-d, a drawbar arrangement 101 according to another embodiment of the invention is illustrated. Similar to the drawbar arrangement 1 , the drawbar arrangement 101 has a base portion 106 and a draw bar 108 pivotably connected to each other around an axis B. The drawbar arrangement 101 further comprises a locking mechanism for fixating the base portion 106 with respect to the drawbar 108. More specifically, a locking member 110 is arranged in a slot 111 in the drawbar 108, so as to be movable along the drawbar between a front, unlocked position, and a rear, locked position. In the locked position, the locking member 110 is received by a matching opening 112 which is centrally located in the base portion 106.

In figure 4a, the locking member 110 is in the unlocked position, and the base portion 106 can pivot freely with respect to the drawbar 108. The drawbar 108 is shown in a rotational position forming an angle a with respect to a central (“neutral”) position.

In figure 4b, the locking member is in the locked position, and has been received by the opening 112. This means the base portion 106 is fixated in the central position with respect to the drawbar 108, and cannot be pivoted by the actuators 107.

Figures 4c and 4d shows the locking mechanism in more detail. The locking member is here operated by means of a hydraulic spring 113. The hydraulic spring is mechanically connected to the locking member, and biased towards the locked position (figure 4c). Hydraulic pressure is required to move the locking member 110 into the unlocked position (figure 4d).

Turning to Fig. 5, an alternative drawbar arrangement 201 is illustrated. Also in this case, the drawbar arrangement 201 has a base portion 206 and a draw bar 208 pivotably connected to each other around an axis B. In this case, however, the actuator 107 is a circular actuator, for example a planar/worm gear actuator. The circular actuator 107 may be operated such that the base portion 106 is set into the desired rotational position with respect to the drawbar 208, just as discussed in relation to Fig. 1a-b and 2a-b.

With reference to Fig. 6, operation of a full trailer 2 connected to a towing vehicle 11 by the drawbar arrangement 1 will be described.

With a conventional drawbar, the rotational position of the front wheelset 5 would be determined by the position and direction of the towing vehicle pulling (or pushing) the trailer. With a drawbar arrangement according to the present invention, the rotational position of the wheelset 5 will be determined by: a) the movement of the truck 11 relative the orientation of the trailer 2, and b) the pivoting position of the base portion 6 with respect to the drawbar 8.

As the towing direction of the trailer 2 is determined by the rotational position of the wheelset 5, the towing direction is not necessarily in a direction towards the towing vehicle 10. In the illustrated case, the wheelset 5 is oriented in the longitudinal direction of the trailer.

The processing circuitry 32 may be configured to receive a driving scenario indicating at least one of a driving speed, a forward driving direction, a backward driving direction, a steering action, and a rotational position of the wheelset 5 with respect to the trailer frame 3. The driving scenario may be determined and provided to the processing circuitry 32 by an ECU (Electric control unit) 34 of the truck 11 , by manual input by the driver using the user interface 31 , and/or in any way known in the art to determine the driving scenario of the truck 11 . In the illustrated example, the processing circuitry 32 is located in the trailer 2, and connected to the control unit 30 of the drawbar arrangement, while the ECU 34 and user interface 31 are located in the cabin of the towing vehicle 11 . Communication between the various units may be provided by wired or wireless connection.

The processing circuitry 32 is further configured to receive input from the sensor arrangement 33, here including a sensor 33a at the rear of the trailer 2, sensors 33b arranged on the sides of the towing vehicle 11 , a sensor 33c on the front of the trailer 2, and a sensor 33d on the rear of the towing vehicle 11 . Based on the driver scenario and the sensor input, the processing circuitry may be configured to determine a desired rotational position of the wheelset 5, and to provide a control signal to the control unit 30 to operate the actuators 7 to achieve this rotational position.

In a situation when the trailer 2 is going backwards, the sensor 33a is configured to detect the environment in a predicted path of the trailer behind the trailer 2, including any obstacle 62. The processing circuitry 32 may then, based on the detected environment and the predicted path of the trailer, determine a desired rotational position of the wheelset 5, and to provide a control signal to the control unit 30 to operate the actuators 7 to achieve this rotational position such that the trailer 2 avoids the obstacle 62.

In a situation when the trailer 2 is moving forward, sensors 33b, 33c and 33d may detect an environment in a predicted path substantially in front of the trailer 2, including any obstacles 64, 65. The processing circuitry 32 may then, based on the detected environment and the predicted path of the trailer, determine a desired rotational position of the wheelset 5, and to provide a control signal to the control unit 30 to operate the actuators 7 to achieve this rotational position such that the trailer 2 avoids the obstacles 64, 65.

In a situation when the processing circuitry 32 is not able to determine a predicted path wherein all obstacles 62, 64, 65 are avoided, the processing circuitry 32 may provide a warning signal. The warning signal may be received by the driver which may control the truck 11 accordingly. Further, the warning signal may be received by the ECU 34 which may automatically put the truck 53 to a stop (e.g. by activating the brakes).

The user interface 31 may present data associated with the set of parameters in an upcoming environment of said trailer received by the user interface 31 . Subsequently, the driver may input the operational parameters based on the present data on the user interface in order to control the pivot position of the drawbar such that the detected obstacles 62, 64, 65 are avoided when the trailer 2 is moving. The operational parameters may for example be a direction inputted by an operation means by the driver. In another example, the driver inputs a target destination that may be transmitted from the user interface and received by the processing circuitry 32, which in turn calculates a target predicted path of the trailer based on the target destination and subsequently controls the truck and the pivot position of the drawbar such that the trailer follows the target predicted path. In yet another example, the driver may select a selected path such that obstacles behind or in front of the trailer are avoided. Subsequently the control unit may control the truck and the pivot position of the drawbar such that the trailer follows the selected path. The processing circuitry 32 may calculate a number of available paths and present the number of available paths to the driver by the user interface, and the driver may select one of these as the selected path.

The processing circuitry 32 may be configured to automatically output the set of operational parameters indicating at least one of a direction, a path and a target destination based on the set of parameters. Subsequently the truck 11 may be automatically controlled based on the operational parameters such that the obstacles 62, 64, 65 in front or behind the trailer 2 are avoided.

The drawbar arrangement 1 may further comprise a navigational system 35 for providing geographical data to the processing circuitry 32. The navigational system may typically be a satellite-based navigation system and may be selected from the group Global Positioning System (GPS), Galileo, Global Navigation Satellite System (GLONASS), Compass Navigation Satellite System (CNSS), Indian Regional Navigation Satellite System (IRNSS) and BeiDou Navigation Satellite System (BDS). The geographical data may comprise at least a geographical position, wherein the geographical position may comprise known obstacles and/or available space associated with the geographical position. The navigational system 35 is here shown as located in the cabin of the towing vehicle 11 , but may alternatively be located in the trailer. The processing circuitry 32 may, based on the geographical data, control the rotational position of the wheelset 5 solely or in combination with input from the sensor arrangement 33.

In order to power hydraulically, electrically and/or pneumatic devices on the trailer 2, a power transmission from the truck to the trailer may be used. In other words, a power system of the truck may be connected to the power system of the trailer in order to transmit hydraulic, electric and/or pneumatic power from the truck to the trailer. Preferably, the necessary power is transported within the drawbar to shield the hydraulic, electric and/or pneumatic lines from wear and tear. Accordingly, the drawbar of the drawbar arrangement may comprise a power transmission line being at least one of a hydraulic line, a set of electric lines and a pneumatic line. The drawbar may further comprise a first connection port for each type of power transmission line within the drawbar and for receiving power from the truck, wherein the first connection port is arranged adjacent the coupling means. The drawbar may further comprise a second connection port arranged on the drawbar adjacent the base portion for the power system of the trailer to connect to.

Thus, the power system of the truck may be connected to the first port of the drawbar and the power system of the trailer may in turn be coupled to the second port of the drawbar. The power system of the drawbar may be pre-coupled such that when the drawbar mates with the coupling of the truck and the power system of the truck connects to the first connection a power transmission between the power system of the truck and the power system of the trailer is established. Further, it should be understood that the coupling of the truck may comprise automatically connecting power lines for automatically connect with the first connection when the coupling means and the coupling of the truck mate.

The trailer may further comprise a power storage means. The power storage means may be at least one of an electrical battery, a pressurized hydraulic tank, and a pressurized pneumatic tank. Thereby, controlling the pivot position of the drawbar before the drawbar is attached to the truck is enabled by using energy (electrical or mechanical) in the storage means.

With reference to Fig. 7 a method 100 for controlling a drawbar arrangement will be discussed. The trailer may be identical to the trailer discussed in relation to e.g. Fig. 1a or Fig. 1b. Hence, the trailer comprises a frame having at least a rear wheelset and a front wheelset. The drawbar arrangement comprises a base portion for attachment to the front wheelset of the trailer. The drawbar arrangement further comprises a sensor arrangement, and a first actuator connecting a drawbar of the drawbar arrangement to the base portion. The trailer is communicatively coupled to a control unit configured to control the first actuator. The method comprises the steps

- detecting 110, by the sensor arrangement, a set of parameters in an upcoming environment of the trailer,

- determining 120 a desired pivoting position of the drawbar based on the set of parameters,

- controlling 130, by the control unit, the first actuator based on the set of parameters in an upcoming environment of the trailer such that the drawbar is pivoted based on the desired pivoting position of the drawbar.

The set of parameters in an upcoming environment of the trailer may comprise parameters associated with at least one of a coupling position of a truck or an intermediate trailer in front of the trailer and a position of the drawbar. The desired pivoting position of said drawbar is determined based on the coupling position and/or the position of the drawbar.

The set of parameters in an upcoming environment of the trailer may comprises parameters associated with an environment in a predicted path of the trailer and the desired pivoting position of the drawbar is determined based on the environment in the predicted path of the trailer. Further, any functions or features as described in relation to the arrangement are equally applicable in the method. E.g. the arrangement is described as being controllable by pivoting the drawbar with an actuator acting on a central drawbar, this is also to be understood as a method step. Optionally, it is disclosed that the drawbar arrangement may comprise a right drawbar and a left drawbar and that at least one of the drawbars are adjustable in length with the first actuating means, so as to adjust the lateral position of the drawbar. These features are also understood to be applicable method steps disclosed herein.

It should however be understood that the trailer 52 may be coupled to an intermediate trailer (not shown) by the drawbar 54 of the drawbar arrangement 51 . Accordingly, the intermediate trailer may be arranged between the trailer 52 and the truck 53. The intermediate trailer may also comprise a drawbar arrangement identical to the drawbar arrangement discussed to Fig. 2a - 2b or the drawbar arrangement discussed to Fig. 3.