Electric heating – Heating devices – With power supply and voltage or current regulation or...
Reexamination Certificate
1999-01-06
2001-08-21
Paschall, Mark (Department: 3742)
Electric heating
Heating devices
With power supply and voltage or current regulation or...
C219S202000, C219S501000, C297S180120
Reexamination Certificate
active
06278090
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a device for heating a seat, according to the preamble of appended claim
1
. In particular, the invention can be applied in connection with a motor vehicle with electrically heatable seats for those travelling in the vehicle. The invention also relates to a method for heating such a seat, according to the preamble of appended claim
10
.
BACKGROUND OF THE INVENTION
For reasons of comfort and safety, electrically heatable vehicle seats are used in modern vehicles. The driver's seat, as well as the other seats in the vehicle, can be so arranged that they can be heated by means of special heating elements in the form of electrically conducting wires which can be placed in each seat in the form of a heating coil. Such a heating element is normally placed in the back-rest and the cushion of each seat when the seat is manufactured. The heating element is furthermore connected to a current feeding unit which delivers current. In this manner, the heating element can be heated to a suitable temperature.
A problem in previously known heating elements is due to the desire for each seat to have a carefully adjusted temperature on its surface, i.e. on that surface which is in contact with the person travelling in the vehicle. For this purpose, the temperature of the heating element can be controlled by means of a temperature sensor which is arranged close to the heating element, and which is connected to a central control unit. Using the temperature sensor and the control unit, the present temperature can be detected. The control unit also comprises current feeding circuits which, for example, can be based on transistor or relay technology for feeding current to the heating element. In this way, the central control unit is arranged to feed a certain current to the heating element until a certain desired set value for the temperature is reached. The adjustment of this set value can be done either by means of fixed resistances or by means of an adjustable potentiometer which is adjusted by the person travelling in the vehicle.
Using the above described control method, current can be delivered to the heating element until the central control unit indicates that the set value has been reached. When this happens, the control unit will cut off the power feeding. This will cause the heating element to successively cool down. When the heating element has cooled so that its temperature again is below the set value, the power feeding will be resumed. In this way, the temperature control will continue as long as the system is operative.
Although this previously known system normally provides a reliable heating and temperature control for a vehicle seat, it however has certain drawbacks. One such drawback is due to the fact that the heating element is normally fixed in the vehicle seat when manufactured, and the heating element is adjusted according to a certain “normal seat”, i.e. a seat which is defined in advance with a certain given design, upholstery, etc. The seat in this way comprises a heating element for heating the surface of the seat to a certain set temperature. However, when assembling the vehicle the manufacturer might choose to provide the seat in question with, for example, a completely different upholstery, for example a considerably much thicker upholstery than that of said “normal” seat, i.e. an upholstery which differs from that which the temperature control originally was intended for. The temperature value which is detected by the temperature sensor will reach the set value when the heating element has reached the desired temperature, but since an abnormally thick upholstery then is used on the seat, the temperature which is present on the surface of the seat will be too low. This situation thus creates an undesired deviation in the temperature control.
Another drawback of previously known systems for heating seats is that they normally comprise relatively complex and extensive electronic circuits for temperature control and current feeding to the heating element. There are, for example, PCB-solutions where a multitude of components are arranged on a certain circuit board. This might create problems as regards the reliability of the heating system.
A further drawback of previously known systems is that malfunctions can occur, for example in the heating element, without information being transferred to any central unit. For example, short circuits and breakdowns in the wire can occur in the heating element without being detected in a secure and efficient manner.
SUMMARY OF THE INVENTION
A main object of the present invention is thus to provide an improved heating of a vehicle seat in which the above-mentioned drawbacks are eliminated. This is obtained by means of a device of the initially mentioned kind, the characteristics of which will become evident from appended claim
1
. The object is also obtained by means of a process of the initially mentioned kind, the characteristics of which will become evident from appended claim
10
.
The device according to the invention is intended for the heating of a seat which comprises a heating element which is connected to a control unit. The control unit comprises current feeding organs for feeding a current through the heating element so that it can be heated. There is also a temperature sensor connected to said control unit for detecting the temperature at the heating element, with the control unit being arranged for feeding said current if the measured temperature falls below a predetermined set temperature. The invention is based on the control unit comprising a communication unit for receiving information regarding said set temperature from an external unit via a transmission channel. The external unit can preferably be an existing central computer unit in the vehicle. This enables the information regarding the desired set value for the temperature control to be provided in an exact manner which can be adjusted to individual seat designs already during manufacture of the vehicle in question.
According to an advantageous embodiment, the communication unit is also arranged for transmitting further information to the external unit. In this way, status and error information regarding the function of the heating element and the control unit can be transmitted from the control unit to the external unit.
The device according to the invention permits a very high reliability since most of its components can be integrated in one and the same integrated circuit.
Advantageous embodiments will become evident from the appended dependent claims.
REFERENCES:
patent: 4411385 (1983-10-01), Lamkewitz
patent: 4926025 (1990-05-01), Wilhelm
patent: 5075537 (1991-12-01), Lorenzen et al.
patent: 5203497 (1993-04-01), Ratz et al.
patent: 5288974 (1994-02-01), Hanzic
patent: 5948297 (1999-09-01), Haubner
patent: 5981918 (1999-11-01), Topp et al.
Aiff Björn
Fristedt Tommy
Kongsberg Automotive AB
Lerner David Littenberg Krumholz & Mentlik LLP
Paschall Mark
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