GB939292A - Method of heating in vehicles - Google Patents

Abstract

939,292. Electric heating films. P. EISLER. Jan. 17, 1961 [Jan. 25, 1960; March 8, 1960], Nos. 2582/60 and 8095/60. Class 39 (3). [Also in Groups XXXI and XXXV] In a motor vehicle, an electric heating system is provided for the occupant seating space incorporating heating films carried by and insulated from at least one wall of the seating space and which emits radiant heat into the space, there being a further heating means which may operate independently and provides heat at a lower rate and may be a conventional heating system using waste heat from the engine or may comprise means for supplying the electric heating system with less electric power. The arrangement provides for the electric system to be available when the engine is cold and for a conventional heater to be used as desired when the engine is hot. As shown, the vehicle is provided with a conventional heater 211 incorporating a heat-exchange device heated by the engine cooling system, and is also provided with electrical heating films 213, 214, 215, 217 and 220 which may be disposed at the rear of the front seats in door panels, along shelves, in the floor and roof of the vehicle, and tape 222 disposed in the body columns for heating its interior, and film 223 and tape 224 for de-icing the body or drying paint. The films may also be incorporated in floor mats and loose seat covers or may be bonded to the car body-if made of metal sheet-before it is painted. A heater unit 221 for de-misting the rear window may be controlled by a switch 221<SP>1</SP>. Each film may comprise a layer of slitted aluminium foil 226 sandwiched between layers of insulating material 227, 228, the foil being pre-stressed so that if it becomes cracked the edges will separate to break the electric circuit. Portions of the foil adjacent the slit are folded back on themselves, 232, Fig. 2B, and the foil, which may be lacquered on one side, may extend beyond the edges of the insulating material and the extensions used for joining adjacent films. The insulating material may be an elastomeric material, paper or polyvinyl chloride and the conductive layer may be a coating of carbon or graphite instead of the foil. The vehicle generator has armature windings 236 and 237 and field winding 262 connected as shown in Fig. 3 to the poles 242, 243, 244, 240, 245 of a two-position switch 241 operable from the dashboard, shown in the " closed " position in which the windings 236 and 237 are placed in series. In the " open " position, the windings 236 and 237 are in parallel. The pole 243 is connected by a line 265 to the pole 242 and by a line 266 to an armature 267 urged by a spring 271 to establish contact between a pair of terminals 268 and 270. The line 266 includes resistances 274, 275 and 276 and is connected to the terminal 257 of switch 241. The terminal 270 is connected to the junction of resistances 274 and 275 and by a line 280 to a terminal 281 of a switch 282, the other terminal 278 of which is connected to the junction of resistances 275 and 276 by a line 277 which is also connected to the terminal 252. When the switch 282 is closed, the resistance 275 is shorted out. The terminal 248 is connected by a line 283 to the winding of a solenoid 272 which, when energized, separates the contacts 268, 270, and by a line 283 to a single pole three-position switch 284 having an " off " position, a position whereby it connects the line 283 to a line 285 connected to the heating elements 223 and 224 and a position where contact is established with a line 286 which connects by way of a solenoid 287 to a bus-bar 288. The bus-bar 288 may be connected by a pole 291 of a two-position switch 290 to a busbar 293 which at the same time establishes connection between busbars 297 and 294 by a pole 292, heating elements 225 being connected between the bus-bars 288, 297 and 293, 294. The bus-bars may be constituted by strips of foil or the edges of films as shown in Figs. 2A and 2B. The switch 290 is connected to an armature 301 urged towards the switch closing position by a spring 300 and towards the position to open the switch by the coil 287 when the voltage reaches a predetermined value. The switch 290 may also be manually controlled by a switching member 302 having a cam slot 303 in which slides a pin 308 connected to the switch 290 the member 302 sliding in sleeves 304, 305. A pair of contacts 310 are open in the position shown but are closed to short out the coil 287 when the member 302 is moved. The terminal of switch 241 is connected by a line 312 to a winding 313 of solenoid 272 which is tapped by lines 314, 315 leading respectively to the lighting and ignition circuits and to the battery. Cut-out devices 316, each containing a solenoid acting against a spring ensure that the circuits are only completed when the voltage generated is higher than that of the battery. Terminals 250 and 256 of switch 241 are connected to a shunt coil 317 which forms part of solenoid 272 and which is connected to earth by way of a temperature compensating resistor 318. Pulleys 320, 321, 330, 331, 323, 324, 332 and 333 are mounted on an engine-driven shaft 322, a layshaft 325 and the generator driving shaft 334, clutches 326 and 335 for clutching pulleys 323 or 324 to shaft 325 and 332 or 333 for shaft 334 being controlled by bars 336 and 327, a link 337 preventing clutch 326 from clutching pulley 323 to shaft 325 when clutch 335 is in the position in which it clutches the pulley 333 to the shaft 334. The bar 336 is movable between its two positions by movement of switch 241 and the bar 327 is movable between its two positions by movement of switch 290. Operation.-At the beginning of a journey when the engine is cold, the switch 241 and a switch 246 connected to the heater 211 are closed. The coils 236 and 237 are in series and current passes to the line 283 and when the speed of the engine reaches a pre-determined value, the solenoid 287 moves the armature 301 against the spring 300 so as to move the switch 290 to the position shown in dotted lines when the heating films 225 between the bus-bars 288 and 297 and 293 and 294 are placed in series. At the same time, clutches 326, 335 are moved to engage pulleys 324 and 333 to their respective shafts thereby regulating the generator speed to maintain approximately the same temperature. If the voltage rises to a predetermined value, the solenoid 272 opens the contacts 268, 270, whereby resistance 274 is inserted in the generator field. At a desired temperature, the electrical heating system is switched-off by opening switch 241 which places the windings 236, 237 in parallel, cuts-off supply to line 312 but maintains a supply to the battery through line 283. The switch for heater 211 may not be affected by this operation. The generator, which may be water or oilcooled and may be an A.C. generator used in conjunction with a rectifier, may have armature windings of anodized aluminium foils. A point 340, 341 may be provided for heating electric kettles or other devices. The parts of the multipole switch 241 which carry a heavy current may comprise conductors 386 and 387 interconnected by a block comprising a wedge 380 of carbon and a plate 378, insulated from the conductor 386 by a member 381. A layer of foil 377 surrounds the thicker portion of the carbon wedge and is backed by a rubber plate 382 and a spring steel plate 383. The foil and its backing members are normally out of contact with the carbon wedge towards its thin end and a very small current flows through the thick part of the wedge. By rotating a cam member 384, the foil 377 is brought to contact the plate 378 so causing a gradual increase in the rate of current flow. In a modification, Fig. 5, the generator 342 supplies accumulators 350 and 351 by way of a control device 343 and multipole switch 344, 345, 346. The accumulator 350 is that normal for the vehicle and that, 351, supplies the heating current. In the lefthand position of the switch, the heaters are supplied through a line 352 from which auxiliaries, e.g. an electric kettle, may be supplied from points 354, 353 and the accumulator 350 may be charged through a rectifier 355 which safeguards against discharge of the accumulator. The accumulator 351 is charged in the left-hand position of the switch through an overload protection device 356 comprising an armature 357 urged away from a terminal 358 by a spring 360 and brought into contact therewith by a solenoid 361 as long as the voltage of the generator and/or accumulator is sufficiently high. When the heaters are not being used the accumulator 351 will be charged through the overload protection device 356 providing the current is sufficiently high. In a further modification, Fig. 6, similar to the arrangement of Fig. 7, two six-volt accumulators 362 and 363 are charged at twelve volts in series and discharged at six volts in parallel. In another embodiment, Fig. 7, an enginedriven shaft 365 drives, through pulleys 366 and 367, a generator 370 which is connected through a control 371 to an accumulator supplying the normal ignition and lighting circuit of the vehicle. An additional generator 376 is driven through pulleys 372 and 374 and supplies current through a control device 380 to a line 391 connected to the heater units. An electric kettle or other device may be supplied from the points 392, 393. Specifications 900,516, 900,518, 905,867, 908,680 and 912,980 are referred to.