TECHNICAL FIELD

The invention relates to an operating device according to the preamble of claim 1. The application relates also to a motor vehicle according to claim 11.

BACKGROUND

There are various ways for a driver of a motor vehicle, particularly of heavy motor vehicles such as trucks, to cope with difficult conditions such as steep upgrades and running surfaces with poor grip. The vehicles may for example be equipped with load transfer systems and tag axle lift systems. These systems are also used for distributing over a plurality of wheel shafts the weight of any freight carried. The vehicle will normally have a powered axle with two powered wheels and normally also a load-bearing tag axle. The load transfer system usually uses air bellows in a suspension system of the vehicle for raising and lowering the load-bearing tag axle, thereby regulating the pressure on the powered axle. If both of the powered wheels slip, the driver can thus raise the load-bearing tag axle to increase the pressure on the powered axle so that the powered wheels can gain a grip. The load transfer system is controlled manually by its button being kept pressed in for a lengthy period until a desired load transfer level is reached (it may in certain operating situations take several minutes to reach a desired load transfer level). This entails the driver having to judge for him/herself the extent to which the powered axle can be loaded, which he/she is usually not well equipped to do. It also means that the driver's concentration is diverted away from traffic during the time taken to reach a desired load transfer level, nor can the driver pay attention to anything else. The problem of having to set in motion or drive a vehicle up steep upgrades on running surfaces with such low friction that its powered wheels slip on the running surface, thereby limiting the possibility of driving the vehicle, can also be solved by totally discharging the tag wheels, thereby increasing the pressure by which the powered wheels are applied to the running surface and hence allowing a greater friction force between powered wheels and running surface. On trucks this is traditionally done by the tag wheels being raised by a purpose-made lifting device. This may involve using, for example, the device described in WO99/55576. Tag wheel discharge may in certain cases be only possible at relatively low travel speeds, depending on the configuration of the vehicle and possibly on laws and regulations of the country in which the vehicle is running. Tag wheel discharge is affected manually by button pressing by the driver in the cab. Tag wheel discharge involves a maximum load transfer being first affected automatically and the tag axle thereafter being lifted.

The buttons for the two functions of load transfer and tag axle lift take at the present time the form of two separate buttons situated on the instrument panel beside the steering wheel. The buttons for these two functions are confusingly alike and it can be confusing for the driver to have two buttons which perform approximately the same task. A further problem is that the load transfer button has to be kept pressed in for a lengthy period until a desired load transfer level is reached, and that the driver has to watch the instrument panel to see when the desired level is reached. This leads to his/her concentration being diverted from traffic. A further problem with the load transfer button is that the driver has to judge for him/herself the extent to which the powered axle can be loaded, which he/she is usually not well equipped to do. OBJECT OF THE INVENTION

An object of the present invention is to propose an operating device for a motor vehicle which makes easy and safe setting of a switching means possible so that the operability and driving safety of the motor vehicle are improved. This is achieved with devices which exhibit the features indicated in the characterising parts of the independent claims 1 and 11. Preferred embodiments of the operating device are defined in the attached dependent claims 2-10

The problems of today's solutions are solved by the two buttons for the load transfer function being replaced by an operating device which is fitted on the instrument panel and comprises a switching means used for setting at least two drive functions, the one drive function being a load transfer function and the other a tag axle lift function. The driver can directly choose a load transfer level in order thereafter to concentrate on traffic and other tasks without having to keep a finger on the button and watch the instrument panel. This means that these two related functions are combined in a single operating device, resulting in a more ergonomic and functional setting of these two functions.

The two buttons being replaced by one switching means simplifies the setting of the switching means, with consequent improvement of the vehicle's operability and driving safety. A switching means of the operating device which is, for example, arranged for rotation makes it easier for a driver to regulate the load transfer in that no button needs to be kept pressed in, since the driver can instead directly select a load transfer level. This makes quicker setting of the load transfer level possible without the driver having to take his/her eyes off the road. The fact that the switching means provided can also be used for setting at least two drive functions makes easy and quick setting of these drive functions possible, since the driver uses a single switching means for setting them. Great user-friendliness and simplicity requirements apply to an operating device which has two or more functions. The operating device needs to be easy, intuitive and natural to use. A further object of the invention is therefore to propose a user-friendly and logically configured operating device.

DESCRIPTION OF THE DRAWINGS

The present invention will be better understood with reference to the following detailed description read together with the attached drawings, in which the same reference notations pertain to the same items throughout the many views, and in which:

Fig. 1 depicts schematically a side view of a heavy vehicle;

Fig. 2 depicts a known button for load transfer function;

Fig. 3 depicts a known button for tag axle lift function;

Fig. 4a depicts schematically a front view of an operating device for setting a load transfer function and a tag axle lift function of a motor vehicle according to a first embodiment of the present invention;

Fig. 4b depicts schematically a side view of the operating device according to Fig. 4a;

Fig. 5a depicts schematically a front view of an operating device for setting a load transfer function and a tag axle lift function of a motor vehicle according to a second embodiment of the present invention;

Fig. 6a depicts schematically a front view of an operating device for setting a load transfer function and a tag axle lift function of a motor vehicle according to a third embodiment of the present invention; Fig. 6b depicts schematically a side view of the operating device according to Fig. 6a;

Fig. 7a depicts schematically a front view of an operating device for setting a load transfer function and a tag axle lift function of a motor vehicle according to a fourth embodiment of the present invention;

Fig. 7b depicts schematically a side view of the operating device according to Fig. 7a;

Fig. 8 depicts schematically a block diagram for control of drive functions via the operating device according to a variant of the present invention;

Fig. 9 depicts schematically a motor vehicle comprising an operating device according to the present invention.

DESCRIPTION OF EMBODIMENTS

Figure 1 depicts an engine-powered heavy vehicle 1 on an earth running surface 2. The vehicle 1 comprises a tag wheel arrangement 3 which comprises tag wheels 5 and their tag axle, a first main wheel arrangement 6 which comprises powered wheels 8 and their powered axle, and a second main wheel arrangement 9 which comprises steerable wheels 11 and their steerable axle. In the present example, the vehicle 1 comprises a total of four main wheels 8, 11. The vehicle is not limited to comprising one or more wheels of a single type. The invention is applicable to all types of heavy vehicles with a tag axle or other extra wheel shaft which can be raised, eg trucks and buses.

When the vehicle 1 travels on a low-friction earth running surface 2, the grip of the powered wheels 8 on the earth running surface 2 can be improved by discharging the tag wheels 5, which can be done by raising the tag wheels 5 or by reducing the pressure by which the tag wheels 5 are applied to the earth running surface 2, thereby increasing the application pressure and grip of the main wheels 8, 11 on the earth running surface 2. This makes it possible for the vehicle 1 to travel in situations where, for example, the powered wheels 8 would otherwise slip, as when moving off or when on an upgrade where the earth running surface 2 is slippery.

The vehicle 1 comprises an ELC (electronic level control) load transfer system which uses an air bellows suspension system in the vehicle to keep the vehicle at a desired level above the ground. Load transfer involves using the ELC system to make it easier for the driver to cope with difficult conditions such as steep upgrades or running surfaces with poor grip, by causing the ELC system to increase the powered axle pressure. This is done by using the air bellows in the vehicle's air suspension system to regulate the position of the load-bearing tag axle in such a way that the auxiliary axle is moved upwards closer to the vehicle's chassis, thereby reducing the proportion of load carried by the load-bearing tag axle and increasing the proportion of load carried by the powered axle and hence the pressure on the powered axle. The factors which control the available driving power allowed by the running surface are the normal force and the friction between the running surface and the powered wheels. The normal force increases when the powered axle force increases, resulting in more available driving power. There are, however, various limitations, both legal and technical, on the extent to which the powered axle pressure can be increased. Stresses on the dhveline, which comprises the engine, gearbox, propeller shaft and drive shafts, may be very great, with consequent risk of breakdown.

At present, load distribution functions such as load transfer and tag axle lift with ELC are activated by means of the known load transfer function button depicted in Figure 2 for distributing the load on the tag and powered axles, and the known tag axle lift button depicted in Figure 3 for raising the tag wheels 5 and their tag axle. At present, these two buttons are located separately on the instrument panel 10 beside the steering wheel. The buttons for the two functions are confusingly alike and it may be confusing for the driver to have two buttons which perform approximately the same task.

Fig. 4a depicts schematically a front view of an operating device I for setting two drive functions, the one drive function being a load transfer function and the other a tag axle lift function, of a motor vehicle according to a first embodiment of the present invention, and Fig. 4b depicts schematically a side view of the operating device I according to Fig. 4a arranged on an instrument panel 10 of a motor vehicle.

The operating device I is intended to be arranged on the instrument panel 10 in the driver's space of the vehicle. The operating device I comprises a square element 20 intended to be firmly arranged on the instrument panel 10.

The operating device I comprises a switching means 30 which is surrounded by the square element 20. The switching means 30 has a circular base portion 32 accommodated sealingly in and arranged for movement relative to the square element 20. The switching means 30 has also a preferably centrally transverse gripping portion 34 in the form of a knob running across and protruding from the base portion 32.

The switching means 30 is adapted to using the same type of movement to set at least two drive functions, both a load transfer function and a tag axle lift function. Drive function here means a function/device which is suitable for increasing the operability/dhvability of the vehicle on smooth, slippery or similar running surfaces, and incorporates functions such as load transfer and tag axle lift. In this embodiment, a first and a second movement are thus integrated in the operating device I in a single switching means 30.

According to a first embodiment of the present invention, the switching means is arranged for rotation to set load transfer function and tag axle lift function by a rotary movement. Symbols denoting various states of the load transfer and tag axle functions are provided on the side of the firmly arranged square element 20 which faces the user. The gripping portion 34 has a first end 34a and a second end 34b which is diametrically opposite relative to the base portion, which base portion narrows from the first end to the second end, and the second end 34b constitutes the end of the gripping portion 34 or knob 34 which indicates a drive function selected by the rotary movement. The selected drive function and setting position of the switching means are also indicated by a symbol in a display on the instrument panel 10.

The switching means 30 comprises a plurality of fixed rotational positions for setting of load transfer function and tag axle lift function. In this example there are six different positions for the gripping portion/knob 34 for the rotary movement by the gripping portion/knob 34, here 0, %, 14, % for the load transfer function and one position for the tag axle lift function. The switching means might however also have stepless settings.

Switching means for effecting rotary movement for acting upon at least one drive function of a vehicle refers to any desired suitable rotatable means by which a rotary movement can be effected manually by a driver so that said switching of drive functions is made possible. Such a rotatable switching means takes preferably the form of some kind of knob such as the rotatable switching means 30 according to the aforesaid embodiment I. The knob has according to the description and drawings a narrowing shape for effecting rotary movement. The rotatable switching means might also take the form of a configuration resembling a steering wheel.

Figure 5 depicts schematically a front view of an operating device Il for setting two drive functions, the one drive function being a load transfer function and the other a tag axle lift function, of a motor vehicle according to a second embodiment of the present invention. The operating device Il is intended to be arranged on an instrument panel in the driver's space of the vehicle. The operating device Il comprises a square element 20 intended to be firmly arranged on the instrument panel 10.

The operating device Il comprises a switching means 130 arranged for sliding and surrounded by the square element 20. The switching means has a rectangular base portion 132 accommodated sealingly in and arranged, for example, for sliding horizontally/vertically relative to the square element 20 according to the arrow A. The switching means 130 has also a preferably centrally transverse gripping portion 134 in the form of a slide button 134 running across and protruding from the base portion 132.

The switching means 130 is adapted to using the same type of movement, such as said sliding movement, to act upon at least two drive functions of the motor vehicle, both a load transfer function and a tag axle lift function. In this second embodiment, the first and the second movement are thus integrated in the operating device Il in a single switching means 130.

According to this second embodiment of the present invention, the switching means is arranged for sliding to set load transfer function and tag axle lift function by a sliding movement.

Symbols denoting various states of the load transfer and tag axle functions are provided on the side of the firmly arranged square element 20 which faces the user. The gripping portion 134 indicates by its position on the square element the drive function selected. The selected drive function and setting position of the switching means are also indicated by a symbol in a display on the instrument panel 10.

In this example there are six different positions for the gripping portion 134 for the sliding movement by the gripping portion 134, here 0, %, 14, % for the load transfer function and one position for the tag axle lift function. Figure 6a depicts schematically a front view of an operating device III for setting two drive functions, the one drive function being a load transfer function and the other a tag axle lift function, of a motor vehicle according to a third embodiment of the present invention and Fig. 6b depicts schematically a side view of an operating device III according to Fig. 6a arranged on an instrument panel 10 of a motor vehicle.

The operating device III is intended to be arranged on the instrument panel 10 in the driver's space of the vehicle. The operating device III comprises a square element 20 intended to be firmly arranged on the instrument panel 10.

The operating device III comprises a switching means 230 which is surrounded by the square element 20. The switching means 230 has a rectangular base portion accommodated sealingly in and arranged for movement relative to the square element 20. The switching means 230 has also two ends 232a; 232b, the upper end 232b being higher than the lower end 232a. Engagement of a drive function is effected by a pressing movement on the upper end 232b, and disengagement by the lower end 232a.

The switching means 230 is adapted to using the same type of pressing movement to set at least two drive functions, both a load transfer function and a tag axle lift function. In this third embodiment, the first and the second movement are thus integrated in the operating device III in a single switching means 230.

According to this third embodiment of the present invention, the switching means is arranged for pressing for drive function setting by a pressing movement.

Symbols denoting various states of the load transfer and tag axle functions are provided on the side of the firmly arranged square element 20 which faces the user. The gripping portion 232 indicates by the pressing movement a drive function selected on the square element 20. The selected drive function and setting position of the switching means are also indicated by a symbol in a display on the instrument panel 10.

The switching means 230 comprises a plurality of fixed pressing positions for setting of load transfer function and tag axle lift function. In this example there are six different positions for the gripping portion 232 for the pressing movement by the gripping portion 232, here 0, %, 14, ³ A for the load transfer function and one position for the tag axle lift function.

Figure 7a depicts schematically a front view of an operating device IV for setting two drive functions, the one drive function being a load transfer function and the other a tag axle lift function, of a motor vehicle according to a fourth embodiment of the present invention, and Fig. 7b depicts schematically a side view of an operating device according to Fig. 7a arranged on an instrument panel 10 of a motor vehicle.

The operating device IV is intended to be arranged on the instrument panel 10 in the driver's space of the vehicle. The operating device IV comprises a square element 20 intended to be firmly arranged on the instrument panel 10.

The operating device IV comprises a switching means 330 which is surrounded by the square element 20. The switching means 330 has a square base portion 332 accommodated sealingly in and arranged for movement relative to the square element 20. The switching means 30 has also a lever 334 arranged substantially centrally across the base portion 332.

The switching means 330 is adapted to using the same type of movement to set at least two drive functions, both a load transfer function and a tag axle lift function. In this fourth embodiment, the first and the second movement are thus integrated in the operating device IV in a single switching means 330.

According to this fourth embodiment of the present invention, the switching means is arranged for linear movement to set load transfer function and tag axle lift function by a linear movement. Symbols denoting various states of the load transfer and tag axle functions are provided on the side of the firmly arranged square element 20 which faces the user. The lever 334 has a first end 334a shaped like a ball 334a and a second end 334b which is arranged on the square base portion 332. The lever's first end 334a constitutes the end of the lever 334b which indicates by the linear movement a selected drive function on the square element 20. The selected drive function and setting position of the switching means are also indicated by a symbol in a display on the instrument panel 10.

The switching means 330 comprises a plurality of fixed positions for setting of load transfer function and tag axle lift function. In this example there are six different positions for the lever 334 for the linear movement by the lever 334, here 0, %, 14, % for the load transfer function and one position for the tag axle lift function.

Figure 8 depicts schematically a block diagram of a system 400 for control of drive functions via the operating device I; II; III; IV according to the present invention. The system 400 comprises the operating device I; II; III; IV, an electronic control unit (ECU) 410 and the drive functions 430, 440, 450. A first drive function 430 comprises a load transfer function and a second drive function 440 comprises a tag axle lift function according to the embodiments depicted in Figs. 3-7. A third drive function 450 might comprise a function different from the first and second drive functions.

The operating device I; II; III; IV is connected to the electronic control unit 410 in such a way that when the switching means according to the present invention is acted upon by a type of movement to a certain state for the drive function of the motor vehicle, a movement-based signal 430a is sent to the electronic control unit 410, which control unit is adapted, on the basis of the movement-based signal 430a, to sending a signal 430b to a drive function 430, 440, 450 of the respective motor vehicle so that the selected drive function is engaged. Depending on the position of the switching means, various movement-based signals 430a are sent to the electronic control unit 410 so that at a certain position of the switching means a certain movement- based signal 430a is sent to the electronic control unit 410, which sends a signal 430b, eg to engage a drive function 430, 440, 450.

Fig. 9 depicts schematically a motor vehicle 1 comprising an operating device I, II, III, IV according to the present invention.

According to a variant, the square element 20 might have a shape other than square on its circumferential/peripheral portion, e.g. circular, rectangular, triangular, etc.

According to the above embodiments, the symbols on the operating device take the form of numerals, but they might take any desired appropriate form suited to and making clear the drive function associated with each position. The angular spacing between the symbols on the square element, i.e how long a rotational step the user has to effect to set a drive function, is preferably such that said rotary movement will be convenient for the user, and is preferably also adapted to the number of symbols/rotary steps required for the specific rotatable switching means, in that the spacing may be greater in cases where fewer rotational steps are required.

In the embodiments as above, the switching means is adapted to acting upon the load transfer function and the tag axle lift function of the vehicle. However, the operating device might comprise a plurality of other drive functions, such as a differential function, transfer gearbox for all-wheel drive or traction control (TC).

In the above embodiments, the operating device is, for example, arranged on the instrument panel of a motor vehicle, but it might be situated at any desired location of the vehicle which would be suitable for the driver, e.g. between the seats, on the steering wheel, on the door close to the driving seat etc. The invention is thus not to be regarded as limited to the embodiments indicated above but may be varied within its scope indicated by the attached claims.