Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
1997-12-09
2001-09-11
Wayner, William (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S174000, C062SDIG001
Reexamination Certificate
active
06286327
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to apparatus for air conditioning the cabin of a motor vehicle. More particularly, the invention relates to a refrigerant fluid circuit for such an apparatus, the circuit being of the type comprising an air conditioning loop and also a heating loop, providing space heating, the heating loop comprising a heating branch of the circuit in which there are connected distribution means and expansion means.
BACKGROUND OF THE INVENTION
A refrigerant fluid circuit of the above type is known from French patent specification FR 2 717 126A, and from the specification of French patent application no. 9611325. The refrigerant fluid is able to flow either in the air conditioning loop, with the circuit operating as a conventional air conditioning circuit, or in the heating loop, in which case the circuit is then operating as a heating circuit which gives additional heating.
In a circuit of that type, as is explained in particular in French patent specification no. 9611325, the distribution means in the heating branch comprise a stop valve of the two-way type, which is preferably an electromechanical valve. This stop valve, which operates on a “all or nothing” basis, is controlled in coordination with a further stop valve which is connected in the second branch, in such a way that they together constitute a fluid flow switching means for controlling the flow of fluid in the air conditioning loop or in the heating loop.
In this known circuit, expansion means are also provided, being connected in the heating loop downstream of the distribution means with respect to the direction of flow of the refrigerant fluid. This expansion means, which enables the flow of refrigerant fluid in the heating branch to be interrupted or restricted momentarily, is preferably made in the form of a differential pressure regulator which enables the refrigerant fluid to flow only when the pressure difference between its inlet and its outlet exceeds a predetermined threshold value.
Thus, in this known circuit, it is necessary to provide two different means so as to ensure, on the one hand, the function of distribution of the refrigerant fluid into the heating loop, and on the other hand, the function of expansion of the refrigerant fluid in the gaseous state. The known circuit thus has the disadvantage that it calls for two components to fulfil these two functions, and this adds to the size of the apparatus.
In addition, the differential pressure regulator interposed in the heating branch does not enable the quantity of refrigerant fluid flowing in the heating loop to be perfectly controlled as a function of demand.
DISCUSSION OF THE INVENTION
A main object of the invention is to overcome the above mentioned drawbacks.
According to the invention in a first aspect, a refrigerant fluid circuit for a motor vehicle, of the type comprising an air conditioning loop together with a heating loop which includes a heating branch in which distribution means and expansion means are connected, is characterised in that the distribution means and expansion means are in the form of a single component which is a variable opening valve connected in the said heating branch.
This variable opening valve not only enables the expansion of the gaseous refrigerant fluid in the heating branch to be controlled (that is to say in an additional heating mode), but also enables the heating branch of the circuit to be isolated when the circuit is operating in the air conditioning mode.
The use of a variable opening valve also enables the refrigerant fluid circuit to be simplified because this valve combines the expansion means and the distribution means, namely the stop valve, into a single component. In addition, this valve enables two additional functions to be provided, in that it enables the expansion to be controlled, for example from an electronic regulating module, and also enables the time delay before opening of the expansion device to be controlled in the charging mode. This enables the quantity of refrigerant fluid charged into the circuit to be controlled more effectively. Thus, switching of the refrigerant fluid into the heating loop, and expansion of the fluid, are carried out by one valve which controls the mass flow of the fluid over the whole range of 0% to 100% of its nominal mass flow rating.
In one preferred embodiment of the invention, the variable opening valve is an electromechanical valve in the form of either a gate valve or a proportional valve governed by a pulse width modulated signal.
According to a preferred feature of the invention, the variable opening valve is governed by a control unit. Preferably, the control unit is connected to means for measuring the pressure of the refrigerant fluid at a selected point in the circuit.
The invention is particularly applicable to a refrigerant fluid circuit of the type comprising a first branch containing an evaporator followed by a compressor, a second branch containing a condenser, and a third branch containing no condenser, the said third branch constituting the said heating loop. In such a circuit, the variable opening valve is preferably connected in the said third branch of the circuit.
Such a circuit, preferably, further includes means for switching the fluid flow, arranged to deliver the fluid leaving the first branch selectively either into the second branch or into the third branch. In that case, according to another preferred feature of the invention, the fluid flow switching means comprises a first valve connected in the second circuit branch upstream of the compressor, and a second valve connected in the third branch, the said second valve being the said variable opening valve.
Thus, diversion or switching of the fluid flow is carried out by a stop valve connected in the second branch, together with a variable opening valve connected in the third branch, the variable opening valve enabling the various functions mentioned above to be achieved.
According to a further preferred feature of the invention, the first valve and the variable opening second valve are associated with a control unit.
In a preferred embodiment of the invention, the first valve and the variable opening second valve are incorporated in a common valve module. In that case, preferably, the valve module has a body in the form of a monobloc member in which the first valve and the variable opening second valve are contained, the said monobloc member having first, second and third ports for connection to the said first, second and third circuit branches respectively.
In preferred versions of this last mentioned arrangement, the monobloc body of the valve module has an internal passage which puts the first port (and the compressor outlet) into communication with the first valve (and the second branch) and the variable opening second valve (and the third branch), the first valve and the variable opening second valve being connected to the second port and the third port respectively.
In preferred embodiments of the invention, the second and third ports are open in a main face of the monobloc body of the value module while the first port is open in an end face of the body.
In some versions of the invention, the monobloc body of the valve module further has a fourth port for connection to a pressure sensor. Preferably, the said fourth port is open on the other end face of the monobloc body of the valve module, opposite to its other end face in which the first port is open. With this arrangement, the fourth port is able to communicate with the first port and to detect the pressure at the compressor outlet.
According to yet another preferred feature of the invention, the monobloc body of the valve module is a machined block having the general form of a parallelepiped, formed in a metallic material, preferably an aluminium alloy.
According to the invention in a second aspect, a valve module is provided for a refrigerant circuit, the module having any or all of the features thereof mentioned above.
Further features and advantages of the invention will appear more clea
Morgan & Finnegan , LLP
Valeo Climatisation
Wayner William
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