Refrigeration – Automatic control – Of external fluid reheating
Reexamination Certificate
1999-09-28
2001-04-24
McDermott, Corrine (Department: 3744)
Refrigeration
Automatic control
Of external fluid reheating
C062S176100, C062S176600, C062S196400, C062S159000, C165S204000, C165S231000, C165S254000
Reexamination Certificate
active
06220042
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a method for treating an air flow to be sent into the passenger compartment of a vehicle, in which the air flow, before being exposed where necessary to a heat source, passes through an evaporator which forms part of a refrigerating fluid circuit also comprising a compressor, a condenser and at least one pressure reducing valve, taking account of the choice made by a user between at least one working mode of the said circuit in which the fluid circulates in the evaporator so as to modify the temperature of the air flow and an idle mode in which the fluid does not circulate in the evaporator.
Such a method is commonly used for air conditioning the vehicle passenger compartment. It is also used, by means of a refrigerating fluid circuit like those described in FR-A-2 717 126 and FR-A-2 731 952, in a working mode where the evaporator yields heat to the air flow, in order to supplement an insufficient contribution by the heat source, in particular when the latter is a heat exchanger through which the fluid cooling the engine driving the vehicle passes, and the engine, and consequently the cooling fluid, have not reached their normal operating temperature.
It is also known that the appearance of mist on the windows can be detected by means of a suitable sensor, and that the sensor signal can be used for triggering an action aimed at eliminating the mist. This action consists of favouring the sending of hot air to the misted glazed surfaces, either by modifying the distribution of the treated air flow between different outlet vents in the passenger compartment, or by an overall increase in the rate of this flow, or by increasing the exchanges between the latter and the heat source, or by combining these different methods. In no case does the signal from the mist sensor act on the circulation of the refrigerating fluid.
BRIEF DESCRIPTION OF THE INVENTION
It has now been discovered that the detection of the presence of mist could advantageously be used for controlling the refrigerating fluid circuit, either for preventing a circulation mode promoting misting, or on the contrary for reserving a circulation mode which is costly in energy for a case where it is useful for demisting.
A first aspect of the invention relates notably to a method of the type defined in the introduction, and makes provision for any presence of mist to be detected on at least one glazed surface of the vehicle to which at least part of the treated flow is sent and for the result of the detection to be taken into account, conjointly with the choice of the user, for defining the conditions of circulation of the refrigerating fluid.
Optional characteristics of the invention, complementary or alternative, are set out below:
The refrigerating fluid circuit has, as a working mode, an air conditioning mode in which the fluid circulates successively through the evaporator, where it vaporises whilst receiving heat from the air flow, through the compressor, through the condenser where it condenses whilst yielding heat to another medium, and through a pressure reducing valve, the air conditioning mode being enabled only in the case of misting, at least in a given temperature range outside the vehicle, and the idle mode being activated when the air conditioning mode is chosen and not enabled.
The air conditioning mode is enabled only in the event of misting below a first external temperature limit value and is enabled independently of the misting above the said first limit value.
The refrigerating fluid circuit has, as a working mode, an additional heating mode in which the fluid circulates in the gaseous state between the evaporator, where it yields heat to the air flow, and the compressor, the enabling of the additional heating mode and/or the flow rate of refrigerating fluid therein being in accordance with the misting.
The additional heating mode is controlled according to the misting below a second external temperature limit value lower than the first limit value, and totally inhibited above the said second limit value, and the air conditioning mode is enabled, in the event of misting, only above the said second limit value.
Above the second limit value, the additional heating mode is inhibited if misting appears whilst this same mode is activated, and enabled in the contrary case.
According to a second aspect of the invention, a signal representing the rate of variation in the degree of misting of a glazed surface in a vehicle is taken into account for managing the treatment of an air flow to be sent at least partly to this glazed surface, and notably to enable or not a working mode in the method according to the first aspect of the invention.
It is also possible to combine the said signal representing the rate of variation in the degree of misting with a signal representing the degree of misting.
According to a third aspect of the invention, the presence of mist and/or the variation in the degree of misting are detected on two regions of the vehicle windscreen remote from each other by means of a single sensor comprising a transmitter which transmits radiation to the said regions and a receiver which receives radiation coming therefrom.
In an advantageous combination of at least two aspects of the invention, the presence of mist and/or the variation in the degree of misting on the top part and on the bottom part of the windscreen are detected, by means of the same sensor or separate sensors, and the detection signals relating to the top part are used to control the air conditioning mode and the detection signals relating to the bottom part to control the additional heating mode.
Another object of the invention is an air treatment device for implementing the method as defined above, comprising a refrigerating fluid circuit including an evaporator, a compressor, a condenser and at least one pressure reducing valve, a heat source, means for causing the said air flow to pass through the evaporator and then in contact with the heat source before sending it at least partly to at least one glazed surface of the vehicle, means for causing the fluid to circulate in the circuit in accordance with at least one working mode, selection means enabling a user to choose between this or these working modes and an idle mode, means for detecting any presence of mist on at least one glazed surface of the vehicle to which at least part of the treated flow is sent and for producing a signal in response to the detection of mist, and control means for controlling the fluid circulation mode according to the choice of the user and the said signal.
The device according to the invention can also comprise means for determining the temperature outside the vehicle, the control means being able to take account of the said temperature.
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patent: 4783970 (1988-11-01), Takahashi
patent: 4878358 (1989-11-01), Fujii
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Petitjean Christophe
Robillard Jerome
McDermott Corrine
Morgan & Finnegan LL
Norman Marc
Valeo Climatisation
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