GB2042290A

GB2042290A - Heating vehicles electrically

Info

Publication number: GB2042290A
Application number: GB8001987A
Authority: GB
Original assignee: Fratelli Borletti SpA; Borletti SpA
Current assignee: Fratelli Borletti SpA; Borletti SpA
Priority date: 1979-02-02
Filing date: 1980-01-21
Publication date: 1980-09-17
Also published as: ES488212A1; DE8002152U1; IT1117627B; FR2447821A1; DE3002980A1; IT7967225A0; FR2447821B3

Abstract

A heating unit for the interior compartment of a motor vehicle comprises at least one heating element (3) housed inside or adjacent to the compartment and supplied by a generator (10), and a battery-driven fan (4). A switching arrangement (12) enables the heating elements and fan to be supplied from an external mains source controlled by a presettable timer. An auxiliary heating element may be located in the floor of the vehicle. <IMAGE>

Description

SPECIFICATION Heating unit for the interior compartment of a motor vehicle This invention relates to a heating unitforthe interior compartment of a motor vehicle.

Most motor vehicles are provided with an internal heating system for the driving compartment. Heating is generally carried out by utilising the heat removed from the main engine by an engine cooling fluid, and conveying this fluid into the interior com partmentthrough feed conduits.

Although such a heating system is almost universally used, it has certain drawbacks. Firstly, the main engine must be running. In addition, when the engine is cold, it is necessary to wait some minutes for it to heat up, and the need to heat the interior compartment during this period generally results in a delay in the engine reaching its operating temperature, so reducing efficiency and partly polluting the environment as the fuel is improperly burnt. The said feed conduits for the cooling fluid must be fitted into the motor vehicle, and although in the case of common motor vehicles this is generally easy, it is difficult in vehicles for agriculture such as tractors, because of their special structure.

The afore said drawbacks are partly obviated by using a district heating system for the interior compartment, which utilises small burners disposed in the compartment. In this case however, there is considerable danger due to the flame developed by the burners.

The object of the present invention is to provide a heating system for the interior compartment of a vehicle which obviates or ameliorates the aforesaid drawbacks of known systems.

The present invention provides a heating unit for the interior compartment of a motor vehicle, characterised by comprising at least one heating element housed inside said internal compartment, and electrical supply means for said heating element; said heating element being arranged to convert electrical energy received from said electrical means into heat energy, so as to become heated and consequently heat said interior compartment of said motor vehicle.

The present invention will be more apparent from the description of a preferred embodiment given hereinafter by way of non-limiting example with reference to the accompanying drawing, in which: Figure lisa perspective view of a motor vehicle comprising a heating unit according to the present invention; and Figure 2 is an electrical schematic diagram of said heating unit.

With reference to Figure l,this shows a motorvehicle, particularly a tractor, indicated overall by 1, and provided with a driving cab 2 comprising internally a compartment for housing the driver. At the front of the inside of the cab 2 there are located a bank 3 of heating elements, for example of the strip or spiral type, and an electrically driven fan 4 arranged to convey air into the compartment of the cab 2 and through the bank of heating elements 3. Two regulators indicated by 6 and 7 are accessible from the compartment interior of the cab 2, and are able to regulate the power dissipated by the bank of heating elements 3 and the speed of the electric motor (not shown) which drives the fan 4.

In Figure 1, the bank of heating elements 3 is supplied by a voltage generator 10, for example a three-phase alternator, which is driven by a power take-off 9, for example the drive shaft of the motor vehicle 1, by way of a belt 11, and the motor of the fan 4 is supplied by a positive voltage taken, in a manner not shown, from a normal accumulator carried by said motor vehicle.

The bank of heating elements 3 and the fan 4 are connected to their respective electrical supplies by way of a multiple switch bank 12, which also allows supply of power from outside the vehicle. The bank of heating elements 3, the fan 4 and the relative regulators 6 and 7 constitute, together with the voltage generator 10, a heating unit, indicated overall by 15, for the compartment contained inside the cab 2 of the motor vehicle 1.

The operation of the heating unit 15 will be more apparent from the description given hereinafter of the relative electrical schematic diagram, with reference to Figure 2.

In particular, the bank of heating elements 3 comprises three heating elements 17,18 and 19 having a first terminal connected together and their second terminal connected respectively to the common terminals of switches 21,22 and 23. A first switching terminal of said switches is connected to respective outputs of the voltage generator 10, which in this case provides an alternating three-phase voltage.

The second switching terminal of the switches 21,22 and 23 is connected respectivelyto outputs of a supply circuit 25 arranged for connection to a normal electrical supply mains by way of terminals 26 and 27. The supply circuit 25 is arranged to convert a single-phase electrical voltage received at the terminals 26 and 27 into a three-phase electrical voltage for supplying the heating elements 17, 18 and 19 as an alternative to the voltage generator 10. An activation signal from a timer circuit 28 is fed to the supply circuit 25, as a result of which it feeds said threephase supply voltage to its outputs.

The voltage generator 10 comprises an excitation winding 30 with a first terminal connected to earth and its second terminal connected to a positive supply pole 31 by way of a circuit comprising, in series in the order stated, switching and common terminals of a switch 32, the regulator 6 comprising for example a common rheostat or an electronic arrangement, common and switching terminals of a switch 33, and an additional slider 34 of a rheostat 35.

With regard to the supply for the electrically driven fan 4, Figure 2 shows a motor 37 for the fan, which has a first terminal connected to earth and its second terminal connected to the positive pole 31 by way of a circuit comprising, in series in the order stated, a common terminal and a first switching terminal of a switch 38, a current regulating block 39, the rheostat 35 and the main slider 40 of the rheostat 35. The rheostat 35 and the block 39 constitute overall the regulator7 (see Figure 1) for the fan 4. The second switching terminal of the switch 38 is connected to an auxiliary output of the supply circuit 25, which receives a direct current signal when the supply circuit 25 is activated by the timer circuit 28.The main slider 40 and additional slider 34 of the rheostat 35 are connected together mechanically for simultaneous operation, as are the switches 21, 22, 23, 32,33 and 38, which together constitute the multiple switch bank 12 shown in Figure 1.

The operation of the heating unit 15 is as follows.

It will be assumed that the main engine of the motor vehicle 1 is running, and that each switch of the bank 12 is positioned as shown in Figure 2.

Under these conditions, the shaft of the voltage generator 10 rotates, but if the sliders 34 and 40 are raised, then no excitation current flows in the winding 30, and therefore no electrical signal is available at the outputs of the voltage generator 10.

When the sliders 34 and 40 are positioned as shown in Figure 2, current flows both through the regulator 6 and winding 30, and through the rheostat 35, block 39 and motor 37. The current in the winding 30 can be regulated by adjusting the regulator 6.

Consequently, as this current is the excitation current for the voltage generator 10, it determines corresponding voltages at the three generator outputs, thus leading to power dissipation across the heating elements 17,18 and 19. Heat energy is therefore produced by said heating elements to an extent depending on the adjustment of the regulator 6, its value being adjustable from zero to a maximum value corresponding to the maximum excitation current which can flow in the winding 30.

The motor 37 of the fan 4 is supplied by way of the rheostat 35 and block 39. The rheostat 35 adjusts the rotational speed of the motor 37 and thus the dispersion of the heat produced by the bank of heating elements 3 into the compartment of the cab 1. The rotational speed of the motor 37 is such that even under minimum speed conditions, corresponding to the entire rheostat 35 being inserted into the circuit, there is sufficient dispersion of the heat produced by the bank of heating elements 3, even if this heat is at its maximum value.

With particular reference to Figure 2, the heating unit 15 can be operated in another manner. In this respect, by operating the switches of the bank 12, the free terminals of the heating elements 17,18 and 19 can be connected to the respective three-phase supply outputs of the supply circuit 25, and the motor 37 can be supplied by the auxiliary direct current output of the supply circuit 25. A time period can be set by the time circuit 28, which can be of the order of some hours, at the end of which the outputs of the supply circuit 25 are made to supply the respective voltage signals. The mains voltage at the terminals 26 and 27 is thus converted both into three-phase voltage and fed to the heating elements 17, 18 and 19, and into direct current for supplying the motor 37 of the fan 4.In this manner, the heating unit 15 is automatically set into operation at a predetermined time, to enable the interior compartment of the cab 2 of the motor vehicle 1 to be preheated.

In this respect, no waiting period is required for commencement of heating inside the cab 2, as under normal conditions heating can coincide with the starting of the engine of the motor vehicle 1.

Such a heating system does not remove heat from the engine, so that this latter can attain its operating temperature and its correct operating condition in a shorter time period.

Finally, the facility for automatically preheating the interior of the cab 2 is particularly advantageous when the motor vehicle 1 is to be used at set times under very low external temperature conditions.

Finally, modifications can be made to the present invention which do not leave the scope of the inventive idea.

For example, the bank of heating elements 3 could comprise heating elements connected differently together from the electrical aspect, or differently disposed inside the cab 2. In particular, one or more heating elements could be housed in the floor of the cab 2 in a region where the driver's feet usually rest, so as to determine a zone of particularly concentrated heating.

Claims

1. A heating unit for the interior compartment of a motor vehicle, comprising at least one heating element housed inside said internal compartment, and electrical supply means for said heating element; said heating element being arranged to convert electrical energy received from said electrical means into heat energy, so as to become heated and consequently heat said interior compartment of said motor vehicle.

2. A heating unit as claimed in claim 1, wherein said electrical means comprise a voltage generator mechanically coupled to a power take-off of said motor vehicle, and arranged to supply said electrical energy as the result of an activation signal received by first regulating means.

3. A heating unit as claimed in claim 2, wherein said voltage generator is an alternator, and said first regulating means enables the intensity of the current passing through an excitation winding for said alternator to be controlled.

4. A heating unit according to any one of the preceding claims said electrical means comprise a supply circuit which can be supplied from the normal electric mains.

5. A heating unit as claimed in claim 4, comprising a timer circuit arranged to transmit an activation signal to said supply circuit at the end of a set time period.

6. A heating unit according to either one of claims 4 and 5 as appendent on either one of claims 2 and 3 comprising switching means for selecting said voltage generator or said supply circuit alternatively.

7. A heating unit as claimed in one of the preceding claims, comprising a fan arranged to cooperate with said heating element in orderto disperse the heat produced by said heating element into the interior of said motor vehicle.

8. A heating unit as claimed in claim 7, comprising second regulating means which enable the rota tional speed of said fan to be controlled.

9. A heating unit as claimed in one of the preceding claims, comprising an auxiliary heating element housed in the floor of said interior compartment, and supplyable by said electrical supply means.

10. A heating unit as claimed in one of the preceding claims, wherein said motor vehicle is a tractor.

11. A heating unit for the interior compartment of a motorvehicle, as described with referencetothe accompanying drawing.

12. A heating unit suitable for heating the interior compartment of a motor vehicle, comprising at least one heating element either housed inside said interior compartment or housed in an enclosed space adjacent to and communicating with the said interior compartment, and electrical supply means for said heating element, said heating element being arranged to convert electrical energy received from said electrical supply means into heat, and consequently heat said interior compartment.