A SENSOR FOR CREATING A FLOW OF AIR AROUND A TEMPERATURE SENSOR

The present invention relates to a device for providing, in a vehicle with a turbo-charged engine, air flow in the passeng¬ er compartment about a temperature sensor belonging to the vehicle climate control unit and placed in the vehicle pas- senger compartment.

It is previously known to utilize the subatmospheric pressure in the intake pipe of an internal combustion engine to pro¬ vide air flow about a temperature sensor belonging to the vehicle climate control unit and disposed in the passenger compartment by having a hose, one end of which is connected to the intake pipe and the other end of which has its mouth in the vicinity of the temperature sensor. Such devices do not work, however, when the turbo-unit in a vehicle with a turbo-charged engine is engaged, since there would then be excess pressure in the intake pipe.

The present invention intends to solve this problem and provide a device of the type described by way of introduction which is effective when the turbo-unit is engaged.

In order to achieve this purpose, a device of the type desc¬ ribed by way of introduction is characterized in that it comprises a jet pump, that the inlet to the jet pump is connected to the charge air pipe and its outlet is connected to the engine fresh air intake, and that a conduit, one end of which opens into the vehicle passenger compartment in the vicinity of the temperature sensor, is connected at its other end to the free end of the suction channel of the jet pump, the other end of said suction chamber opening into the jet pump main channel connecting the inlet and outlet of the jet pump. The ejector effect provides a subatmosphere pressure in the suction channel of the jet pump when the turbo-unit is engaged, and this subatmosphere pressure causes, via the hose to the vehicle compartment, air to flow about the temperature sensor. When the turbo-unit is not in operation, the suction in the engine intake pipe is utilized in a conventional

manner with the aid of a hose with a check valve to cause air to flow about the sensor.

Furthermore, the jet pump is preferably so dimensioned that the subatmosphere pressure which is created in the hose to the vehicle passenger compartment when the turbo-unit is engaged is of the same order of magnitude as the suction created in the hose to the vehicle passenger compartment when the turbo-unit is disengaged as a result of the prevailing subatmosphere pressure in the engine intake pipe. This assu¬ res that the operating state of the turbo-charged engine will not affect the functioning of the temperature sensor and thus the climate control unit.

One embodiment of the invention will now be described with reference to the accompanying drawings, of which Figures 1 and 2 show schematically a device according to the invention mounted in a vehicle with a turbo-charged engine in one view from above and one view from the side, respectively, and

Figure 3 shows schematically one longitudinal section through a jet pump used in the device shown in Figures 1 and 2.

Figures 1 and 2 show one embodiment of the device 1 according to the invention for providing air flow about a temperature sensor (not snown), which is placed in the vehicle passenger compartment and is included in the climate control unit of the vehicle. This device comprises a jet pump or ejector pump 2, which, as can be seen in Figure 3, has a converging-diver- ging main channel 3, connecting the inlet 4 to the outlet 5 of the jet pump. A suction channel 6 opens into the narrower section of the main channel. As is well known to the person skilled in the art, such a jet pump functions by accelerating the air flow in the converging portion of the main channel 3, whereupon the air in the main channel is brought to such a high velocity that the ejector effect sucks air from the suction channel 6 creating a subatmosphere pressure therein. In the diverging portion of the main channel 3, the air flow is retarded at the same time as the air expands, thus crea-

ting a pressure drop in the air flowing in this portion of the channel.

In the device 1, the inlet 4 to the jet pump is connected via a connector 7 to the charge air pipe 8 of a turbo-charged engine, i.e. to the pressure side of a t rbo unit, the comp¬ ressor 9 of which is shown schematically ..n Figures 1 and 2.

The outlet 5 of the jet pump is connected via a hose 10 to a fresh air hose 11 leading to the air intake of the turbo compressor 9, i.e. to the suction side of the turbo-unit.

The suction channel 6 of the jet pump leads via a conduit 12, preferably in the form of a flexible hose, to a temperature sensor (not shown) placed in the vehicle passenger compart¬ ment in such a manner that suction in the hose 12 creates air flow about the temperature sensor. Suitably, this is achieved in the same manner as in a previously known device of this type, in which a hose connected to the intake pipe of a suction engine opens in the vicinity of the temperature sensor, which is placed in a ceiling lamp housing in the vehicle passenger compartment. Other arrangements obvious to the person skilled in the art are, of course, conceivable within the scope of the invention, but the temperature sensor is preferably surrounded by a housing or the like to insure uniform air flow about the sensor and reduce the magnitude of the suction necessary to provide the required air flow about the sensor.

The device according to the invention functions in the follo¬ wing manner.

When the turbo unit is engaged, an overpressure in the charge air pipe creates air flow through the main channel 3 of the jet pump in the direction from the inlet to the outlet.

Through the ejector effect, air is sucked from the suction channel 6 and suction is created thereby in the hose 12 to

the vehicle passenger compartment, and this suction is suffi¬ cient to provide adequate air flow about the temperature sensor.