Temperature sensing device for an internal-combustion engine

This application claims the priority of German application 10124852.0, filed May 22, 2001, the disclosure of which is expressly incorporated by reference herein.

This invention relates to a temperature sensing device for an internal-combustion engine. The invention also relates to an air flow temperature measuring process.

Conventional temperature sensing devices normally comprise sensor elements which permit temperature sensing based on thermodynamic measuring principles, such as a temperature-caused volume change of a fluid, or on the basis of electrical effects, such as changes of a specific resistance. By way of electric lines or thin pipe lines, these sensor elements are connected to a central sensing device. Sensor elements for sensing the engine temperature can be arranged in the area of a cylinder head. Sensor elements for detecting an oil temperature are preferably provided in a line section situated downstream of an oil pump. Sensor elements for detecting an engine intake air temperature can be arranged in an intake line of the engine in front of or behind a filtering device.

By sensing the temperatures of the intake air, the cooling water, and the oil, it is possible to optimize the operation of the engine, particularly with respect to exhaust gas quality. The numerous sensors as well as their coupling to a central engine management unit, however, require high mounting-related expenditures.

It is an object of the invention to provide a temperature sensing device by which at least two measured temperature values advantageously taken into account during the operation of an internal-combustion engine can be sensed in a favorable manner.

According to the invention, this object is achieved by a temperature sensing device for an internal-combustion engine having a carrier structure, a first sensor element accommodated on the carrier structure, a second sensor element accommodated on the carrier structure, an engine air feeding device for feeding an engine intake air flow to the first sensor element, and a radiator air feeding device for feeding a radiator air flow passed through an engine radiator to the second sensor element. The carrier structure is arranged in an area in which the two air flows run adjacent to one another.

As a result, it becomes advantageously possible to centrally sense, by way of a compact and advantageously mountable constructional unit, the temperatures of the two air flows. In this case, the obtained measuring signals can be coupled into a cable tree system provided on the vehicle side while cabling expenditures are reduced. In a particularly advantageous manner, it is possible, for example, prior to an engine start, to check the method of operation of the two sensors with respect to one another and, if necessary, carry out a joint calibration of the two sensors. Because of the local proximity of the two sensor elements, a particularly informative comparison of the respectively sensed temperature values will be possible. Since, during operation of the internal-combustion engine, the temperature sensed by the second sensor element cannot be below the temperature of the intake air, a particularly reliable function testing of the temperature sensing device can be implemented.

The two sensor elements are preferably, by way of the carrier structure, combined with a constructional unit. This results in advantages, particularly with respect to mounting.

According to one particular aspect of the present invention, the two sensor elements are connected by way of common cabling with a cable tree branch provided on the vehicle side. The cabling assigned to the two sensor elements can in this case be connected with the vehicle-side cable tree branch on the vehicle side by way of a common connector plug structure.

Advantageously, the connector plug structure is constructed integrally with the carrier structure. The carrier structure is preferably made of a plastic material and forms a separating wall which separates the two air flows from one another at least before they sweep over the sensor elements.

According to a particular aspect of the invention, the carrier structure is preferably constructed integrally with an air guiding element. This air guiding element is preferably an engine intake air guiding device.

As an alternative thereto, it is also possible to integrate the carrier structure into a blower suspension or a radiator tank of a vehicle radiator. The two sensor elements are preferably arranged adjacent to one another. This results in a particularly compact construction.

The carrier structure is advantageously arranged in an area in which a line device of an engine intake air system extends past a radiator blower. In this area, the engine intake air system is preferably coupled with an engine radiator or a radiator blower device.

It is possible to provide another sensor element, which is also mounted on the carrier structure, for detecting the cooling water temperature. This sensor element preferably is connected also by way of the common cabling to the vehicle-side cable tree.

Additional details of the invention are contained in the following description and the drawings.

FIG. 1 is a schematic representation for explaining a preferred basic construction of a temperature sensing device according to the invention; and

FIG. 2 is an illustration for explaining a preferred installed position of the temperature sensing device according to the invention.

FIG. 1 is a simplified sectional view of a temperature sensing device 1 having a first sensor element 2 and a second sensor element 3 , the first sensor element 2 being provided for sensing the temperature of an engine intake air flow V 1 and the second sensor element 3 being provided for sensing the temperature of the radiator air flow V 2 flowing out of an engine radiator (FIG. 2, reference number 9 ).

The first sensor element 2 and the second sensor element 3 are arranged on a common carrier structure 4 which, in this case, is made of a plastic material and can be mounted by way of a fastening device 5 a, 5 b on an air guiding device 5 c through which the engine intake air flow V 1 flows.

In this embodiment, the two sensor elements 2 , 3 are constructed as PTC sensors, with connection cables 6 which can be connected by way of a plug connector device with a cable tree branch provided on the vehicle side. This connector plug device is preferably constructed integrally with the carrier structure 4 .

In this view, an air guiding device 7 is provided at a distance of approximately 4 to 5 mm above the first sensor element 2 . By way of this air guiding device 7 , a partial flow V 1 ′ of the engine intake air flow V 1 flowing past is intensively guided over the first sensor element 2 in order to reliably sense the temperature of the intake air.

An air guiding device 8 is also provided for the second sensor element 3 . By way of this air guiding device 8 , a partial flow V 2 ′ of the air flow V 2 flowing out of a radiator or vehicle heat exchanger and heated by the engine cooling water is intensively guided over the second sensor element 3 .

In this embodiment, the carrier structure 4 of the temperature sensing device 1 comprises a basic body 9 made of a plastic material by way of which a sufficient thermal separation of the two sensor elements 2 , 3 is also achieved.

The measuring values centrally generated by the described temperature sensing device 1 for the temperature of the engine intake air as well as the temperature of the heated air flowing out of the engine radiator can be fed by way of a single plug connector to a control device, particularly to an electronic engine management system for implementation of OBD-relevant functions. The temperature sensing device can also be part of an automatic air-conditioning system (AOC sensor).

The measuring signals generated by the first sensor element 2 and indicative with respect to the temperature of the engine intake air flow as well as the signals sensed by way of the second sensor element 3 and indicative with respect to the temperature of the air flowing out of the engine radiator can be used for optimizing the operation of the internal-combustion engine as well as for monitoring the latter.

FIG. 2 illustrates in the form of a schematic diagram how the temperature sensing device 1 according to the invention can be arranged in a motor vehicle. In this embodiment, the first sensor element 2 and the second sensor element 3 are in an area situated behind a radiator 9 viewed in the air stream approach direction. An air guiding device 10 guiding the engine intake air flow V 1 extends close enough to a site over which a radiator air flow V 2 sweeps that the temperatures of the engine air as well as of the air guided through the radiator 9 —and heated in the process—can be sensed essentially centrally.

The measuring signals generated by the first sensor element 2 and the second sensor element 3 can be transmitted by way of a connector plug device 11 to a cable tree branch provided on the vehicle side. The connector plug device 11 comprises a coupling section which has an integral construction with the air guiding device 10 .

In addition, the air guiding device 10 is connected with a suspension device 12 of the radiator blower 13 . This suspension device 12 , in turn, is coupled with the radiator 9 . It is possible to also couple the line devices provided for the voltage supply of a motor 14 of the blower device 13 by way of the above-mentioned connector plug to the line system provided on the vehicle side. This results in even further reduced cabling expenditures. As an alternative thereto, it is possible to couple the two sensor elements 2 , 3 by way of contact devices, which are integrated in a blower connector plug, with the vehicle-side line system. In the case of the above-described embodiment, the sensor device 1 is mounted on a structural component of the air guiding device 10 . However, the invention is not limited to such an embodiment. It is, for example, also possible to mount the temperature sensing device 1 , for the combined sensing of the engine intake air as well as of the air heated by a radiator 9 , on a structural component assigned to the blower device 13 or to the radiator 9 itself.

By way of the temperature sensing device 1 according to the invention, it is also possible to sense additional system parameters, such as the cooling water temperature in the radiator 9 . A temperature sensing device 1 of this type is preferably constructed on a structural component assigned to the radiator 9 . By way of the solution according to the invention, it becomes possible to construct the vehicle radiator, the blower device, and its suspension device, as well as the components of the engine intake air guiding device 10 , which are situated in the forward region of the vehicle, as a preassembled construction unit which is equipped with the required sensor devices and which can be advantageously mounted within the scope of an automated mounting operation. It is possible to construct the connector plug device 11 such that, within the scope of the installation of the above-mentioned structural unit into the vehicle, it automatically engages with the connector components provided on the vehicle side.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof