HEATABLE DEVICE

Abstract: The invention provides a heatable device (1) in the form of a flange adapted to be inserted in the inlet manifold of an internal combustion engine between the throttle valve (11) and the inlet manifold (12). The device is provided with an integrated heating element such as a PTC element (3) or helical resistance wire (5) to reduce the formation of ice on the throttle valve in addition to the standard heating. The device is particularly suitable for retro-fitting.

Description: Heatable Device The invention relates to a heatable device adapted to be located adjacent to a gas flow throttle valve in a fuel inlet tract of an internal combustion engine. The formation of ice on the throttle valve of the engine of a motor vehicle is a well known problem, particularly in countries where extremely cold and damp conditions occur. If ice forms on the throttle valve, the correct motion of this is impaired, which can in extreme cases lead to a loss of control of the vehicle. It has long been known to heat either the inlet tract (e.g. DE 3917107) or even the spindle of the throttle valve itself (e.g. DE 4122138) by various means such as using PTC elements (e.g. EP 0138315) or other heating elements (e.g. DE 3426469) . It has also been proposed (GB 863257) to provide a gasket adapted to replace a gasket between the carburettor and inlet manifold having a heating element located in a recess in the gasket. The device is relatively crude and suffers from the problem that the vehicle battery is rapidly drained on use. This device suffers from the further problem that it is not suitable for retrofitting. The above solutions generally achieve their purpose but suffer from design compromises such as restricting the cross sectional area of the fuel flow path or being fairly bulky. Additionally the known devices still do not work satisfactorily under the most extreme conditions, such as in Canada and the Scandinavian countries, or are expensive so that they are not economic to use on mass production vehicles. The present invention seeks to provide a device to reduce or prevent the build up of ice on the throttle valve and inlet manifold that is compact, cheap to manufacture and can be easily retro-fitted to vehicles in countries where it is appropriate. According to the present invention there is provided a heatable device adapted to provide a source of heat for reducing ice build up on a gas flow throttle valve and in an inlet tract of an internal combustion engine, the heating element being outside the gas flow path through the tract, characterised in that the device is adapted to be located adjacent to the gas flow throttle valve in an inlet tract, the device comprising a control in the form of an integrated switch, and an integrated temperature sensor, wherein the device is actuated only under specified conditions. In a preferred embodiment the device is adapted to be inserted adjacent to the gas flow throttle valve. Preferably, the device is actuated for a pre-determined time after starting the engine or after actuation of the vehicle electrical system. The solution according to the invention has the advantage that the device can be retro-fitted by dealers in the countries where extreme icing is a problem which is not satisfactorily solved by the normal inlet manifold heating arrangements . Alternatively it may be fitted on the production line to vehicles destined for those countries without any design modifications being necessary or increasing product assembly time or costs. A further advantage of the invention is that by placing the heating element outside the inner wall of the inlet tract, the gas flow through the tract is not impaired at any stage. Preferably, the source of heat is a PTC element integral with the device. Alternatively the device may be provided with a groove extending around the device , the source of heat being a heating element located in said groove. Preferably said heating element is a helical resistance wire. However, in the area of bores for connecting screws for connecting the device to the tract the heating element may be straight. Preferably the dimensions of the device are such that substantially no adjustment of the position of the throttle valve relative to an inlet manifold part of the tract is necessary to insert the device. Preferably the energy supply for the heating element is taken from the vehicle battery. The energy supply may have a single pole. Embodiments of the invention will now be described by way of example with reference to the drawings in which: Figure 1 shows the device of the invention in-situ; Figure 2 shows a flange-like insert with an integral PTC element and Figure 3 shows a flange-like insert with a channel containing a heating element. Figure 1 schematically shows a part of an internal combustion engine having the device of the invention. The device 1 is located between the part of the inlet tract 10 of an internal combustion engine 14 having the throttle valve 11 and the inlet manifold 12. A thermally conducting gasket 13a, b is placed on both sides of the device 1 to act as the seal between the device 1 and the inlet manifold 12 and the inlet tract 10 having the throttle valve 11. The gasket 13a,b thus enables heating of the throttle valve housing. The device 1 is fairly thin in the longitudinal axis of the tract so that it may be inserted into the inlet tract between the throttle valve and the inlet manifold without requiring any substantial adjustment work on or repositioning of these two parts. The electrical supply for the device 1 is taken from the vehicle battery 8. The device shown in full lines in figure 1 is particularly suitable for retro-fitting. Alternative arrangements are shown in broken lines in figure 1 where the heating element is located directly in the housing of the throttle valve 11 or also upstream of the throttle valve. Figure 2 shows the flange-like device 1 which is essentially annular with four equidistant regions of enhanced diameter, which regions have bores 2a-d to receive the screws joining the throttle valve to the inlet manifold. A PTC heating element 3 of known type is integrally joined to the device 1 adjacent to the bore 2a. The PTC element provides a localised heating to the inlet tract in the region of the throttle valve. A thermally conducting gasket is applied to the surface of the device 1 adjacent to the throttle valve to ensure that the heat provided by the PTC element is conducted around the inlet tract. The electrical supply to the PTC element is taken from the vehicle battery 8. Figure 3 shows an alternative embodiment of the device 1 having four bores 2a-d and a groove 4 extending around the circumference of the device 1. A heating element 5, such as helical resistance wire, for resistance heating runs around the groove 4. A thermally conducting gasket is then applied on top of the groove. Between bores 2a and 2b the device 1 has a slightly larger diameter with respect to the remaining ring-like structure and a recess 6 larger than groove 4 for receiving the electrical supply and control device for the heating element. The electrical supply is taken from the vehicle battery 8 via a single pole, the earth pole being provided by a mass 7 located in the recess 6. The control device 9 is integrated into the PTC element 3 or in the recess 6 functions independently of any control devices already on the vehicle and thus is particularly suitable for the retro-fit market. A semi-conductor switch element, such as a high side switch, is integrated into the control device 9. A temperature sensor is integrated into either the control device 9 or the heating element 3,5 itself. In addition the high side switch contributes to the heating. When the temperature in the inlet tract is below a certain pre-determined level, when ice could form, then upon engine actuation or, alternatively, when there is any actuation of the vehicle electrical system the switch will actuate the heating element. It is also possible to limit the time that the device operates. This control of the actuation of the device prevents draining the battery or reduction of the fuel consumption. Although the device is shown here between the throttle valve and the inlet manifold, it could also be placed on the side of the valve remote from the manifold, if the inlet tract construction was suitable. The device of the invention presents a low cost solution suitable for the limited markets where the situation will occur. Due to its small size the device of the invention can be retro-fitted with only minor modifications, at most, to the inlet tract. By integrating the switching and temperature controls in the device, reliability is enhanced and a compact size achieved.

Claims: Claims 1. A heatable device (1) adapted to provide a source of heat for reducing ice build up on a gas flow throttle valve (11) and in an inlet tract (10) of an internal combustion engine, the heating element being outside the gas flow path through the tract, characterised in that the device is adapted to be located adjacent to the gas flow throttle valve (11) in an inlet tract (10), the device comprising a control (9) in the form of an integrated switch and an integrated temperature sensor (3,5,9), wherein the device is actuated only under specified conditions. 2. A heatable device according to Claim 1, wherein the dimensions of the device (1) are such that substantially no adjustment of the position of the throttle valve (11) relative to an inlet manifold part (12) of the tract (10) is necessary to insert the device. 3. A heatable device according to Claim 1 or Claim 2, wherein the device is actuated for a pre-determined time after starting the engine or after actuation of the vehicle electrical system. 4. A heatable device according to any one of Claims 1 to 3 , wherein the source of heat is a PTC element (3) integral with the device. 5. A heatable device according to Claim 1, wherein the device is provided with a groove (4) extending around the device, the source of heat being a heating element (5) located in said groove. 6. A heatable device according to Claim 5, wherein said heating element has substantially the form of a helical resistance wire (5), wherein in the area of bores (2a, 2b) for connecting screws for connecting the device to the tract the heating element is straight. 7. A heatable device according to Claim 1, wherein the energy supply for the device ( 1 ) is taken from the vehicle battery (8). 8. A heatable device according to Claim 7, wherein the energy supply has a single pole. 9. A heatable device according to Claim 1, wherein the device is located in the throttle valve housing.

Inventors: KLEINECKE UWE, TRIFKOVIC TRIVUN, WELTER LOTHAR, KLEINECKE, UWE, TRIFKOVIC, TRIVUN, WELTER, LOTHAR
Applicants: DAIMLER BENZ AG, KLEINECKE UWE, TRIFKOVIC TRIVUN, WELTER LOTHAR, DAIMLER-BENZ AG, KLEINECKE, UWE, TRIFKOVIC, TRIVUN, WELTER, LOTHAR
Application year: 1997
Main classification: F02M31
IPC codes: F02M31