There are, at present, various forms of air-conditioning system intended for vehicles, especially for buses, and made up of a plurality of sub-systems, which are controlled by way of a control unit. This is generally located by the driver's seat in the vehicle.

The control unit is usually designed to control one or more sub-system components forming part of respective sub-systems. In a known design the control unit is equipped with an actuating element for each sub-system; one of the sub-systems is therefore selected by pressing one of the said actuating elements. When each individual component in a first group of controllable components of the selected sub- system is connected to an associated set of operating controls, the components in the first group can be controlled by the operating controls. By way of the actuating elements new groups of sub-system components can be selectively advanced for connection to the set of operating controls. The number of operating controls in the set defines the size of each group.

An object of the present invention is to provide a control unit, which is easy and quick to operate even on the move, which will lead to increased traffic safety and greater convenience.

This has been achieved by an arrangement of the type initially described, which is characterised in that there is at least one special selection device, which when acted upon will connect at least some of the operating controls in the set to a group of sub- system components specially selected for rapid access, where at least some of the sub-system components in this group derive from different sub-systems.

Preferred embodiments have any or some of the characteristics specified in the subordinate clauses 2-6.

The arrangement according to the invention has a number of advantages. The risk of a traffic accident occurring is naturally reduced if the driver of a vehicle is able to give his full attention to the road, instead of directing his attention towards instruments and control panels by the driver's seat. Because the sub-system components that need to be adjusted most frequently whilst driving the vehicle are

located in the specially selected group, the driver needs to pay less attention to the air conditioning system control unit, thereby improving traffic safety. In one embodiment this is further enhanced in that in the normal setting the specially selected group is displayed, so that the sub-system components in this group can be adjusted without the need to act on any selection device. Since the sub-system components in the specially selected group are interchangeable, components can be exchanged according to the climate, the time of year and the weather conditions or legal requirements, so that the most frequently used sub-system components are always included in the specially selected group.

The invention will be explained in more detail below with the aid of examples of embodiments of the arrangement according to the invention, with reference to attached drawings, in which: figure 1 shows an example of a control unit according to the invention and figure 2 shows an example of a display on the control unit in figure 1, when the display is lit.

In figure 1 the reference number 1 denotes a control unit designed to control a plurality of sub-systems forming part of an air conditioning system intended for vehicles, especially buses. The control unit 1 has a separate selection device for each sub-system, for example in the form of a pressure-sensitive button, which is actuated by touching. In the example in figure 1 there are buttons 2,3,4,5,6 for selecting sub-systems, where the button 2 relates to an air-conditioning sub-system by the driver's seat, the button 3 to an air conditioning sub-system for the passenger compartment, the button 4 to heating when the vehicle is parked, the button 5 to blowers and the button 6 to a further air conditioning sub-system for the passenger compartment. Each sub-system comprises one or more sub-system components. By selecting sub-systems by pressing any of the buttons 2,3,4,5,6 each separate component in a first group of controllable components in the sub-system selected is connected to an associated set of operating controls 7,8,9,10, so that the components in the first group can be controlled by way of the operating controls 7,8, 9,10. The buttons 2,3,4,5,6 can furthermore be selectively advanced in order, by means of the set of operating controls 7,8,9,10, to connect a further group of controllable components in the selected sub-system. For example, for button 2, air- conditioning sub-system for the driver, associated sub-system components may include temperature, foot-level blowers, windscreen blowers etc. The number of

operating controls in the set naturally defines the size of the respective group. In the example in the figure therefore, the maximum size of the group is four components.

There is also a special selection device in the form of a button 11, which when pressed connects at least some of the operating controls 7,8,9,10 in the set to a group of sub-system components specially selected for quick access. This specially selected group includes the sub-system components that need to be adjusted most often when on the move, regardless of the sub-system to which the components belong. If the driver of the vehicle needs to alter the settings of these commonly occurring sub-system components, he/she therefore only needs to press the button 11 in order to adjust the settings of the components by way of the operating controls 7, 8,9,10. The alternative, of course, would have been, for each sub-system, to advance the right component group, to find the right component and then to adjust the setting via one of the operating controls. The sub-system components in the specially selected group are also interchangeable. The user therefore has the facility for changing accessible sub-system components in the specially selected group so that the components in the selected group correspond to prevailing conditions.

Suitable sub-system components in the specially selected group may, of course, be dependent on the prevailing climate, time of year and the weather conditions or legal requirements. The changing of components in the specially selected group is preferably undertaken when the vehicle is parked. There will be many possible ways known to the person skilled in the art of providing the facility for altering sub-system components in the specially selected group.

According to one preferred embodiment the set of operating controls 7,8,9,10 is in the normal position connected to the specially selected group of sub-system components, so that the settings for these specially selected sub-system components can be adjusted without even needing to press the button 11. Furthermore the control unit 1 in this example is preferably designed to return to the normal position once a predetermined length of time has elapsed after any setting of any of the sub-systems has been adjusted by way of the buttons 2,3,4,5,6 and the operating controls 7,8, 9,10. It is therefore not necessary to use the button 11 at all, unless access to the specially selected group of sub-system components is desired during the above- mentioned period of time. In all other cases the sub-system components in the specially selected group are directly accessible so that the settings can be adjusted by way of the operating controls 7,8,9,10.

The control unit in figure 1 also has a number of further buttons in order to control the air conditioning system. There is an on/off button 12, a timer button 13, a recirculation button 14 and a button 15 for automatic setting of the air conditioning system. The control unit also has a display 16.

As will be seen from figure 2, the display 16 is divided up into four parts 16a, 16b, 16c, 16d, one for each operating control. In a second embodiment (not shown) the control unit 1 has four separate displays. The display 16 is designed, when any of the buttons 2,3,4,5,6,11 is pressed, to indicate, in respect of each operating control in the set, which sub-system components are in the activated group. The display is furthermore designed, when any of the buttons 11 is pressed, to indicate, in respect of each operating control in the set, the setting of each sub-system component in the activated group. As will be seen from figure 2, the sub-system components may have either an On or Off setting or may have numerical values corresponding, for example, to a power output of the blowers, the temperature etc.