GB1578643A

GB1578643A - Control of the internal enviroment of a coach

Info

Publication number: GB1578643A
Application number: GB3241677A
Authority: GB
Original assignee: Karl Kaessbohrer Fahrzeugwerke GmbH
Current assignee: Karl Kaessbohrer Fahrzeugwerke GmbH
Priority date: 1976-08-02
Filing date: 1977-08-02
Publication date: 1980-11-05
Also published as: FR2360433B1; NL7708340A; ES461039A1; HU184644B; CH626296A5; FR2360433A1; GR61636B

Abstract

The method is intended to eliminate wrong decisions by an operator in the heating and aerating of a bus and to permit optimum aeration and air-conditioning of the interior of the bus. This is achieved in that the driver's compartment and the passenger compartment are separately supplied with air, the driver's compartment being aerated via at least one front air inlet and the passenger compartment being aerated via at least one air inlet located in the rear region of the side walls or of the roof and the two compartments being vented via at least one joint air outlet arranged in the low-pressure region, which is established when driving, of the front end of the bus, and in that when a central switch is switched on the passenger compartment is heated under the control of a thermostat whereas the heating of the driver's compartment is manually controlled.

Description

(54j THE CONTROL OF THE INTERNAL ENVIRONMENT OF A COACH (71) We, KARL KASSBOHRER FAHRZEUGWERKE GMBH, a German Body Corporate, of Peter-Schmid-Str. 13, 7900 Ulm/Donau, Germany, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to the control of the internal environment d a coach such as by heating, cooling or ventilating the interior of the coach.

It is customary in coaches to heat and ventilate both the driver's cab as well as the passenger compartments together. For this purpose, most coaches have an air inlet at the front through which air may flow into the coach near the driver. Part of the air ob- tained in this way is directed to the windscreen and the driver's cab, while the other part is conducted to the passenger compartment. Blowers serve to circulate the air. To heat the interior od the coach, underfloor heaters may be provided and a so-called heat box may be located at the front of the coach near the air inlet to be operated centrally by the driver just like other heaters.

This type of heating and ventilating system for the interior of a coach suffers from considerable drawbacks. The driver is distracted during his main task of driving the coach, by having to operate the heating and ventilating system. Moreover, he is not in a position to accurately monitor and adjust the temperature and air conditions in the passenger compartment from the driver's cab. He will often miscalculate when operating the heating and ventilating system, since he will tend to regulate the system according to his subjective feelings in response to the environmental conditions prevailing in the driver's cab. If the sun is shining on the driver, for example, be will hardly be likely to turn up the heating, although this would perhaps be considered unpleasant to those passengers sitting in the shade. Similar considerations apply to operation of air-conditioning or cooling systems.Although incorrect operation of the ventilating and heating system can be merely unpleasant for the passenger, incorrect operation when cooing or air-conditioning the interior can result in marked harmful consequences for the passengers, since it is a well known fact that incorrectly operated airconditioning systems are a frequent cause of colds caught by the passengers.

According to the present invention, there is provided a method od ventilating, and controlling the temperature od, the interior of a coach having a driver's cab and a passenger compartment, comprising feeding air into the cab through at least one front air inlet, feeding air into the passenger compartment through at least one air inlet located at the rear end portion d the passenger compartment in the zone of the roof thereof, with the air feed to the cab being separate from the air feed to the passenger compartment, withdrawing air from the cab and the passenger compartment through a common air outlet located in a region of negative pressure at the front of the coach and generated during forwards movement thereof, and heating the driver's cab and the passenger compartment, with the temperature of the driver's cab being controlled manually, and the heating function, for the passenger compartment being brought into operation by actuation of a control switch whereafter control of the temperature of the passenger compartment is effected automatically by thermostatic means.

Further according to the present invention, there is provided a system for carrying out the above method, comprising at least one front air inlet for feeding air into the driver's cab, at least one air inlet located at the rear end portion of the passenger compartment in the zone of the roof thereof for feeding air to the passenger compartment separately from the air feed to the driver's cab, a common air outlet for the driver's cab and the passenger compartment, said air outlet being at the front of the coach in a zone of negative pressure generated during forwards movement of the coach, means for heating the passenger compartment, switch means operable to actuate the passenger compartment heating means, said passenger compartment heating means comprising conduit means traversed by a heating medium and which is connected to heat exchangers whose heat output can be regulated, blowers at least some of which are operative to provide the heat exchangers with air, and first regulating means operable to regulate the heat output of the heat exchangers and to regulate the output of the associated blowers and to thereby control the temperature of the passenger compartment, said first regulating means comprising thermo statically-controlled regulating valves for regulating the flow of heating medium through the heat exchangers and thermostatic regulators for controlling at least some of said blowers, and means for heating the driver's cab and comprising at least one further heat exchanger whose heat output can be regulated by hand and at least one further blower whose output can be regulated by hand, said further blower being associated with the further heat exchanger.

Preferably, the system includes a cooling or air-conditioning function provided by means of heat exchangers for cooling the air, with these heat exchangers being incorporated in a coolant circuit comprising a compressor.

Regulating means for regulating the output of blowers for forcing air through these heat exchangers into the passenger compartment, can be actuated by a central switch and includes at least one thermostat.

Preferably, the air inlets and the air outlets of the passenger compartment are designed as slots provided above the side windows of the coach and are adapted to be closed by controllable flaps. Such slots fit the external appearance of the coach wall. They are also provided at a height where relatively fresh air can be drawn in. The slots can be closed in whole or in part with the air of the flaps whose position is variable, thereby regulating in a simple manner the supply and removal of fresh air.

Preferably, at least some of these flaps can also be controlled by the regulating and control means. This ensures that, if a pre-set programme is used, the flaps will be adjusted in accordance with this programme. If the coach is to be heated, for example, then it is sufficient to ventilate the coach with the air of one air inlet and air outlet, whilst the remaining slots are closed and sealed with the air of the flaps.

Yet further according to the invention, there is provided a coach comprising first ventilating means and first heating means for the driver's cab, said first ventilating means comprising an air inlet for the driver's cab, said first ventilating means and said first heating means being controllable by the driver, second ventilating means and second heating means for the passenger compartment, and switch means operable by the driver to actuate the second heating means, said second ventilating means comprising an air inlet for the passenger compartment, this inlet being separate from the air inlet for the driver's cab, and said second heating means including means for automatically controlling the operation of the second heating means so that predetermined environmental conditions are attained in the passenger compartment after operation of the switch means, said coach further comprising air outlet means for the driver's cab and the passenger compartment in a zone of negative pressure generated during forwards movement of the coach.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a circuit diagram of a heating and ventilating system for a coach; Figure 2 is a circuit diagram of a heating, ventilating and air-conditioning system for a coach; Figure 3 is a longitudinal section through a coach incorporating a system as shown in Figure 1 or Figure 2, the section being taken on line II--II in Figure 4; and Figure 4 is a side elevation of the coach.

As shown in Figure 1 the heating and ventilating system la comprises two circuits, namely a circuit 2 for the heating medium and which is shown in relatively solid lines, and an electrical circuit 3 which is shown in thin lines.

The heating circuit 2 is a dual pipe circuit such that each of the heat exchangers present in the circuit has an inlet connected to a supply pipe 4 and an outlet connected to a discharge plipe 5. Both pipes are connected to the cooling water system of the engine of the coach in a manner not shown. The pipes extend from the engine, which is installed in the rear of the coach, along the entire length of the coach to the front which is at the top in Figure 1, the arrow P in the Figure indicating the forwards direction of travel.

A so-called heat box for heating and ventilating the driver's cab is located at the front of the coach. This heat box comprises a heat exchanger 6 which is connected to both pipes 4 and 5 and which is preceded by a blower 7 which draws fresh air into contact with the heat exchanger 6. The blower 7 communicates with a front air inlet 34 of the coach as shown in Figure 4.

The blower 7 can be operated at two speeds with the aid of a switch 8. A hand valve 9 is provided to infinitely regulate the heat exchanger 6. With the aid of the switch 8 and the valve 9, the driver himself can adjust the desired heating or ventilation of the driver's cab and the wind-screen.

Heat exchangers 10 and 11 are provided for heating the passenger compartment. The heat exchangers 10 together with blowers 12 are designed as underfloor heaters. The heat exchangers 11 are each equipped with two blowers 13 and are located at the rear end portion of the coach in the roof area thereof adjacent the side walls.

Each of these heat exchangers is connected through a respective inlet pipe 14 to the supply pipe 4 and an outlet pipe 15 to the discharge pipe 5. The heat exchangers 10 serve to heat the air which is recirculated through the coach whilst the heat exchangers 11 are used preferably to heat fresh air.

A water pump 16 is installed in thel supply pipe 4 to circulate the water through the heating circuit. A pre-heating device 17 is also located in the supply pipe to heat the water in the event that the input is toe cold to provide the necessary heat input.

As seen in the direction of travel, additional blowers 18 without associated heat exchangers are provided on each side of the coach in front of the blowers 13 and serve to draw in fresh air or to recirculate the existing air. These blowers are also provided in the roof area adjacent the side walls, like blowers 13.

As indicated in Figure 4, a continuous grating 20 is located above the side windows 19 of the coach. The air inlets and air outlets which will be described in detail below are located behind this grating. These inlets and outlets can be closed by flaps 21, 22 and 23 which are schematically illustrated in Figure 1. The flaps 21 are associated with the air outlets whilst the remaining flaps 22 and 23 are each associated with air inlets.

The electrical circuit is illustrated using only one lead the other lead being earthed to the chassis as is conventional in automotive engineering.

In the driver's cab, a switch 24 is located adjacent to the switch 8 and serves to actuate the heating system for the passenger com partment The blowers 12 and 13 are connected to the electrical circuit 3. Located upstream of the blowers 12, are pairs d thermostats for infinitely regulating the output of the blowers from zero, for example, to half and to full output. In the case of smaller coaches, a thermostat may also be used for regulating all the underfloor heaters. The connections between the blowers 18 in the circuit 3 are shown by dotted lines, these blowers serving primarily for ventilation, but not for heating.

Figure 1 shows a number of sensors 26 each forming part of a corresponding thermo stat. One such sensor 26 is located on the air discharge side of each of the blowers 12 and at rhe air discharge side of only one blower of each pair of adjacent blowers 13.

Each sensor 26 is associated with a respective regulating valve 27 incorporated in the inlet pipe 14 'leading to the corresponding heat exchanger and serving to infinitely regulate the output of the heat exchanger. The operation of the blowers 12 is controlled by thermostats 25. The circuit diagrams of Figs.

1 and 2 (to be described later) are highly schematic, and the parts 26 and 27 form part od the circuit which is controlled by the switch 24.

Figure 3 obthe drawing illustrated the coach travelling in the direction of the arrow P. The air currents which are formed both in the interior and on the exterior are indicated by arrows. The arrows in the interior of the coach indicate the air currents when the heating system is in operation.

It is clearly evident that the air hits the front 28 od the coach and flows around the front end of the moving coach in the form of a bow wave 29 indicated schematically.

The plus and minus signs indicated along the side walls indicate the pressure prevailing there. It is clear that in the area of the front end of the coach, i.e. at the location where the bow wave flows around the front end of the coach a negative-pressure area 30 is formed adjacent the side walls and on the roof. In the example illustrated, this negativepressure area extends approximately beyond the first side window od the passenger compartment. The remaining portions of the side walls and the roof are located in a positive pressure zone.

The driver's cab and the passenger compartment are supplied with air and are heated separately while utilising the above aerodynamic factors as will now be described.

Longitudinal slots defining the air inlets and outlets are provided in the body and extend behind the grating 20 along the entire length of the coach and can be closed by the aforementioned flaps 21, 22 and 23. The slots defined behind the gratings are subdivided into three regions in the case of the illustrated coach, i.e. regions 31, 32 and 33.

Regions 32 and 33 include air inlets on both longitudinal sides, the region 32 only being used as required to ventilate the interior of the coach, whilst the region 33 provides forced ventilation and is usually open except for very few instances. The region 31 provides for withdrawal of air from the passenger compartment as well as from the driver's cab which is provided with fresh air through the front air inlet 34. It is clear in Figures 3 and 4 how the air flowing in through the front air inlet can be directed by the driver to the wind-screen or directly into his cab. To summarise, the driver's cab is fed with air through the front air inlet, while the passenger com partment is fed with air through the air inlets provided in the region 33.Both the passenger compartment and cab are vented through the common air outlet in region 31 so that the air drawn in through the front air inlet and arriving from the driver's cab is immediately discharged after having passed through the driver's cab, without substantially reaching the passenger compartment.

The floor with the centre aisle is also illu strated schematically adjacent the driver's cab in Figure 3 of the drawing. A total of four underfloor heating units 35 are indicated which are arranged in two pairs. These units each include a heat exchanger 10, blower 12 and sensor 26 as illustrated in Figure 1. When the blowers 12 are in operation they draw air from the aisle in the direction of the arrows R and conduct it through heating ducts 36 along the side walls of the coach. The heating ducts have openings through which the heated air is discharged rearwardly into the passenger compartment in an oblique manner as illustrated in Figure 3.Only in the area of the frontmost row of seats does the air flow towards the front in an oblique man ner, this being necessary as the underfloor heating units 35 are mounted above the wheels and the first row of seats is located in front of the wheels. The flow of unheated fresh air which occurs between the air inlets present in region 33 and the air outlet present in region. 31 due to the motion of the coach and the warm air flow are combined in the interior of the coach. The consequence is that the entire interior is supplied uniformly with heated air throughout the entire cross section.

The flaps 21 illustrated in Figure 1 are located in region 31 to close the air outlets, while the flaps 22 are disposed in region 32 together with the associated blowers 18, the flaps 23 together with the heat exchangers 11 and the blowers 13 are associated with region 33.

The following is intended to explain how the heating and ventilation of the coach illustrated in Figures 3 and 4 can be controller It is mentioned as a prerequisite that the flaps 23 and 21 are always opened completely during normal use of the coach, and they will only be closed under special circumstances such as when washing the coach, for example. If the driver wants to heat only his cab, he manually adjusts the valve 9, thereby determining the heat output of the heat exchanger 6. With the aid of the switch 8, the speed and thus the output of the blower 7 can be regulated in steps, thereby conveying heated air. This can be fed directly into the cab and onto the wind-screen as the driver desires. The heated air is immediately vented to the atmosphere again after having passed through the driver's cab through the air outlets provided in the region 31.

The procedure for heating the passenger compartment is initiated by actuating switch 24. Hence, the driver only takes a basic deci- sion to operate the heating system for the passenger compartment whereas the regulation of the heating system is effected automatically when the system is in operation. The thermo stats 25 and the thermostats associated with sensors 26 are preset to predetermined theoretical values. If the actual temperature does not correspond to the present theoretical values, the blowers 12 will be switched to the first or second step according to the measured differences. Also, the regulating valves 27 will be opened according to the measurements made by the sensors 26 in order to adapt the output of the heat exchangers to the actual requirements.If the measured interior temperature corresponds to the theoretical value, neither the blowers nor the heat exchangers will be put in operation.

This applies not only for the heat exchangers 10 of the underfloor heating units, but also to the heat exchanger 11 mounted in the roof area whose output can also be regulated by a regulating valve 27.

When switch 24 is actuated, the blowers 13 automatically operate at half their maximum output.

If the driver wishes only to ventilate his cab, the natural current of air through the front air inlet is available to him which he can increase with the aid of the blower 7 which can be regulated in steps. The fresh air obtained in this way is again vented out of the coach along the same routes as described for the abovementioned heated air, i.e. through the air outlets in region 31. If the driver, however, wishes also to ventilate the passenger compartment, another switch (not shown) is available ta him which has a zero, a 1/2 and a 1/1 position. In the zero position, the blowers 18 and 13 are inoperative. The flaps in region 32 are closed when the passenger compartment is heated, the remaining flaps being open.

If the switch is moved to the 1/2 position, the blowers in the roof area, i.e. the blowers 18 and 13, operate at half speed. When the switch is in this position, all the flaps are opened completely.

If the driver moves the ventilation switch to the 1/1 position, the blowers 18 and 13 are operated at full speed, the flaps 21, 22 and 23 remaining completely open. The ventilation switch is subordinate to the heating control switch 24 so that, if both switches are actuated simultaneously, the ventilation flaps 22 will close automatically. The combined heating/ventilating actions can otherwise exist completely which means that the blowers 18 and 13 will operate according to the position of the ventilation switch The flaps 21, 22 and 23 can be closed while washing the coach.

Figure 2 of the drawings shows a heating, ventilating and air-conditioning system lb.

The system is substantially similar to the system la shown in Figure 1, and the same parts have therefore been provided with the same reference numerals. In order to prevent reperition, only the differences between the two systems will be described.

The system ib can be used not only to heat and ventilate the interior of coaches, but also to cool the interior. The first difference to be noted is that two heat exchangers 11 are provided per side wall of the coach mounted beneath the roof. One of them is mounted in the rear area of the side walls.

Figure 2 shows that the flaps 22 are associ ated with heat exchangers. Moreover, the heat exchangers 11 each have four blowers as com pared to two in the case of system la. Whilst the heat exchangers 10 in the underfloor area serve to heat the recirculated air, the heat exchangers 11 are used to heat fresh air or recirculated air.

The heat exchangers 11 respectively form a structural unit in which coolers 37 for use in conditioning the air of the coach are also installed. The coolers are connected in a coolant circuit incorporating a compressor and condensor which are located adjacent the engine. The remaining parts of the airconditioning system, such as a fluid container and drier, are also located adjacent the engine.

The electrical circuit for the air-conditioning system is not shown, but is similar to that of the illustrated heating regulation circuit.

A central switch is located for the operation by the driver and serves to actuate the regulating and control means for the air-conditioning system. At least one thermostat is mounted in the roof area which switches the compressor in stages if there is a difference between the actual and the theoretical rem- perature, and which also regulates stepwise the blowers which force air through the coolers.

When the air-conditioning system is actuated, all flaps are automatically brought to a posa- tion in which the cross-section of the openings of the air inlets and air outlets are reduced by half.

The systems described ensure the optimum ventilation and heating of the entire interior of the coach. Due to the sub-division of the interior into the driver's cab and passenger compartment, it is possible to better comply with the different needs in the two zones.

The driver's cab is ventilated through the front air inlet which guarantees the possibility of rapidly ventilating the wind-screen which becomes necessary during driving. Hence, the driver himself can determine at a quick and reliable manner the ventilation and other internal conditions of his own cab.

The use of a common air outlet from the driver's cab and from the passenger compartment, at the negative pressure zone at the front of the coach is advantageous in that this negative pressure zone normally extends at least over the driver's cab, so no serious disruption to the air supply will be caused by opening the driver's window or the door window, since air can only flow out, but not in through the opened window. In addition, the separate air supplies to these compartments ensure that the air supplied through the front inlet for the ventilation of the driver's cab and which may possibly contain fumes, does not enter the passenger compartment.

The system ensures that the passenger compartment is automatically heated in an optimum manner. The driver merely has the possibility of setting the heaters in operation by actuating a central switch. The actual heat regulation is determined by thermostats whose theoretical value can be predetermined according to the use of the coach. The driver therefore has only the possibility of determining whether or not to heat the passenger compartment. Everything else is done automatically, although he can still regulate the heating of his cab by hand. Similar considerations apply when an air conditioning or cooling function is incorporated. If the driver actuates the switch for the air-conditioning system, then there is no other decision for him to take. The passenger compartment is cooled automatically.If the driver makes a mistake in actuating the air-conditioning system insofar as the theoretical temperature present in the air-conditioning system already prevails in the interior of the coach, the airconditioning system will not begin operation.

The use of thermostatically controlled heat exchangers and blowers as provided for the main heater of the coach which is situated in the under-floor area, prevents large quantities of unheated air from being suddenly blown into the coach interior, thus creating a draught due to a drop in the output of the heat exchanger. The same pleasant thermo static regulation also results when the cooling or air-conditioning function is turned on.

The use of heat exchangers which are infinitely variable and blowers can be regulated in increments leads to a very sensitive, yet inexpensive regulation system.

WHAT WE CLAIM IS:- 1. A method of ventilating, and controlling the temperature of, the interior of a coach having a driver's cab and a passenger compartment, comprising feeding air into the cab through at least one front air inlet, feeding air into the passenger compartment through at least one air inlet located at the rear end portion of the passenger compartment in the zone of the roof thereof, with the air feed to the cab being separate from the air feed to the passenger compartment, withdrawing air from the cab and the passenger compartment through a common air outlet located in a region of negative pressure at the front of the coach and generated during forwards movement thereof, and heating the driver's cab and the passenger compartment,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. same reference numerals. In order to prevent reperition, only the differences between the two systems will be described. The system ib can be used not only to heat and ventilate the interior of coaches, but also to cool the interior. The first difference to be noted is that two heat exchangers 11 are provided per side wall of the coach mounted beneath the roof. One of them is mounted in the rear area of the side walls. Figure 2 shows that the flaps 22 are associ ated with heat exchangers. Moreover, the heat exchangers 11 each have four blowers as com pared to two in the case of system la. Whilst the heat exchangers 10 in the underfloor area serve to heat the recirculated air, the heat exchangers 11 are used to heat fresh air or recirculated air. The heat exchangers 11 respectively form a structural unit in which coolers 37 for use in conditioning the air of the coach are also installed. The coolers are connected in a coolant circuit incorporating a compressor and condensor which are located adjacent the engine. The remaining parts of the airconditioning system, such as a fluid container and drier, are also located adjacent the engine. The electrical circuit for the air-conditioning system is not shown, but is similar to that of the illustrated heating regulation circuit. A central switch is located for the operation by the driver and serves to actuate the regulating and control means for the air-conditioning system. At least one thermostat is mounted in the roof area which switches the compressor in stages if there is a difference between the actual and the theoretical rem- perature, and which also regulates stepwise the blowers which force air through the coolers. When the air-conditioning system is actuated, all flaps are automatically brought to a posa- tion in which the cross-section of the openings of the air inlets and air outlets are reduced by half. The systems described ensure the optimum ventilation and heating of the entire interior of the coach. Due to the sub-division of the interior into the driver's cab and passenger compartment, it is possible to better comply with the different needs in the two zones. The driver's cab is ventilated through the front air inlet which guarantees the possibility of rapidly ventilating the wind-screen which becomes necessary during driving. Hence, the driver himself can determine at a quick and reliable manner the ventilation and other internal conditions of his own cab. The use of a common air outlet from the driver's cab and from the passenger compartment, at the negative pressure zone at the front of the coach is advantageous in that this negative pressure zone normally extends at least over the driver's cab, so no serious disruption to the air supply will be caused by opening the driver's window or the door window, since air can only flow out, but not in through the opened window. In addition, the separate air supplies to these compartments ensure that the air supplied through the front inlet for the ventilation of the driver's cab and which may possibly contain fumes, does not enter the passenger compartment. The system ensures that the passenger compartment is automatically heated in an optimum manner. The driver merely has the possibility of setting the heaters in operation by actuating a central switch. The actual heat regulation is determined by thermostats whose theoretical value can be predetermined according to the use of the coach. The driver therefore has only the possibility of determining whether or not to heat the passenger compartment. Everything else is done automatically, although he can still regulate the heating of his cab by hand. Similar considerations apply when an air conditioning or cooling function is incorporated. If the driver actuates the switch for the air-conditioning system, then there is no other decision for him to take. The passenger compartment is cooled automatically.If the driver makes a mistake in actuating the air-conditioning system insofar as the theoretical temperature present in the air-conditioning system already prevails in the interior of the coach, the airconditioning system will not begin operation. The use of thermostatically controlled heat exchangers and blowers as provided for the main heater of the coach which is situated in the under-floor area, prevents large quantities of unheated air from being suddenly blown into the coach interior, thus creating a draught due to a drop in the output of the heat exchanger. The same pleasant thermo static regulation also results when the cooling or air-conditioning function is turned on. The use of heat exchangers which are infinitely variable and blowers can be regulated in increments leads to a very sensitive, yet inexpensive regulation system. WHAT WE CLAIM IS:-

1. A method of ventilating, and controlling the temperature of, the interior of a coach having a driver's cab and a passenger compartment, comprising feeding air into the cab through at least one front air inlet, feeding air into the passenger compartment through at least one air inlet located at the rear end portion of the passenger compartment in the zone of the roof thereof, with the air feed to the cab being separate from the air feed to the passenger compartment, withdrawing air from the cab and the passenger compartment through a common air outlet located in a region of negative pressure at the front of the coach and generated during forwards movement thereof, and heating the driver's cab and the passenger compartment,

with the temperature of the driver's cab being controlled manually, and the heating function for the passenger compartment being brought into operation by actuation of a control switch whereafter control of the temperature of the passenger compartment is effected automatically by thermostatic means.

2. A method according to claim 1, modified in that the controlling of temperature od the driver's cab and of the passenger compartment is by cooling instead of by heating, the method being performed in a coach equipped with apparatus permitting both the method of the present claim and the method ob claim 1 to be performed and one or the other to be selected.

3. A method according to claim 1, wherein the passenger compartment is heated by feeding air through heat exchange means using blower means, and the temperature of the compartment is controlled by varying the heat output of the heat exchange means and by varying the output of the blower means.

4. A method according to claim 2, wherein the passenger compartment is cooled by blowing air through heat exchange means fed with a cooling medium in a cooling circuit including a compressor, and the temperature of the compartment is controlled by varying the output of the compressor whereby to vary the output of the heat exchange means, and by varying the output of blower means which feeds the air through the heat exchange means.

5. A method according to claim 3 or claim 4, wherein the output of the heat exchange means is infinitely variable and the output of the blower means is variable in steps.

6. A method according to any of claims 1, to 5, wherein at least some of the air inlets and outlets in the passenger compartment are closed when heating the passenger compartment, and all of the air inlets and outlets are partially closed when cooling the passenger compartment.

7. A system for carrying out the method claimed in claim 1, comprising at least one front air inlet for feeding air into the driver's cab, at least one air inlet located at the rear end portion od the passenger compartment in the zone of the' roof thereof for feeding air to the passenger compartment separately from the air feed to the driver's cab, a common air outlet for the driver's cab and the passenger compartment, said air outlet being at the front of the coach in a zone of negative pressure generated during forwards movement ob the coach, means for heating the passenger compartment, switch means operable to actuate said passenger compartment heating means, said passenger compartment heating means comprising conduit means traversed by a heating medium and which is connected to heat exchangers whose heat output can be regulated, blowers at least some of which are operative to provide the heat exchangers with air, and first regulating means operable to regulate the heat output of the heat exchangers and to regulate the output of the associated blowers and to thereby control the temperature of the passenger compartment, said first regulating means comprising thermostatically-controlled regulating valves for regulating the flow of heating medium through the heat exchangers and thermostatic regulators for controlling at least some od said blowers, and means for heating the driver's cab and comprising at least one further heat exchanger whose heat output can be regulated by hand and at least one further blower whose output can be regulated by hand, said further blower being associated with the further heat exchanger.

8. A system according to claim 7, further comprising means for cooling the passenger compartment, and switch means operable to actuate said passenger compartment cooling means, said cooling means including a cooling circuit comprising heat exchange means fed with cooling medium and a compressor for said cooling medium, blower means for providing an air flow through the heat exchange means into the passenger compartment, and second regulating means for controlling the temperature of the passenger compartment, said second control means including at least one thermostat for regulating the compressor output and for regulating the output of the blower means associated with the heat exchange means of the cooling circuit.

9. A system according to claim 7 or claim 8, wherein some of the heat exchangers for heating the passenger compartment and the associated blowers constitute fully thermostatically regulated underfloor heaters, and other heat exchangers whose heating output is regulated by thermostatically controlled regulating valves are mounted in the roof area of the coach and are associated with blowers having a controllable output.

10. A system according to any one ob claims 7 to 9, wherein air inlets and air outlets for the passenger compartment comprise slots which are disposed above the side windows of the coach, and which can be closed by controllable flaps.

11. A system according to claim 9 and claim 10, wherein the heat exchangers mounted in the roof area are associated with air inlets provided in the rear portion of the side walls of the coach.

12. A system according to any one of claims 7 to 11, comprising further blower means located adjacent to air inlets for feeding air at outside temperature into the coach, the output of said further blower means being controllable.

13. A system according to claim 10 or claim I1, wherein at least some of the flaps are controlled by the first or second regulating means.

14. A system according to claim 8, wherein the heat exchange means od the cooling circuit is mounted in the roof area d the coach adjacent an air inlet.

15. A system according to claims 11 and 14, wherein the heat exchangers provided in the roof area and the heat exchange means od the cooling circuit are combined to form a unit.

16. A coach comprising first ventilating means and first heating means for the driver's cab, said first ventilating means comprising an air inlet for the driver's cab, said first ventilating means and said first heating means being controllable by the driver, second ventilating means and second heating means for the passenger compartment, and switch means operable by the driver to actuate the second heating means, said second ventilating means comprising an air inlet for the passenger compartment, this inlet being separate from the air inlet for the driver's cab, and said second heating means including means for automatically controlling the operation of the second heating means so that predetermined environmental conditions are attained in the passenger compartment after operation of the switch means, said coach further comprising air outlet means for the driver's cab and the passenger compartment in a zone of negative pressure generated during forwards movement of the coach.

17. A method of ventilating and controlling the temperature of the interior of a coach according to claim 1, substantially as hereinbefore described with reference to the accom paning drawings.

18. A system according to claim 6, substantially as hereinbefore described with refer- ence to Figures 1, 3 and 4 or Figures 2, 3 and 4 of the accompanying drawings.