Abstract:
A heating and air-conditioning apparatus for the cabin of a motor vehicle. The apparatus includes a chassis within which air flows and equipped with an air-blowing mechanism and heating and cooling units for cooling and heating the air and a member for controlling the heating unit. At least one airflow duct communicates with the chassis, and at least one mixing shutter, with a variable degree of openness, controls the air stream towards the duct. The mixing shutter is arranged in the overall direction of the air flow downstream of the heating member and transmits additional air passing through the heating unit when the fresh air passage is wide open, and governs in an intermediate position of closure of the air flowing through the heating unit. The mixing shutter also switching a control member controlling the operation of the heating unit between an off and on position.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a heating and/or air-conditioning apparatus particularly for the cabin of a motor vehicle. 
     2. Discussion of the Related Art 
     In motor vehicle heating and/or air-conditioning units of the prior art, it is known practice to use an air blowing member, typically a blower, placed upstream of a heating system, typically made up of an evaporator/radiator, allowing the air expelled by the blower to be heated up by heat exchange. In general, a liquid such as water flows around inside the radiator under the control of a progressive valve. These members are placed in succession in a chassis inside which the air flows towards one or more ducts that convey air into the cabin. 
     In addition, a fresh air passage is conventionally formed on the wall of the chassis, outside of the radiator, and a hinged mixing shutter is provided to partially or fully open or close this passage so as to transmit fresh air towards the ducts, or not as the case may be. 
     Control of the temperature of the air conveyed to the ducts is managed by a central unit which controls the valve and the shutter operating in concert. Thus, in a first state, when only hot air is required, the valve is in a wide open operating position and the shutter is closed. All of the air therefore passes through the radiator. When warm air is required, in a variable operating state, the shutter is partially opened and the radiator valve governs the temperature of the water circuit so as to provide warm air which mixes with the fresh air. The progressive nature in raising or lowering the temperature is assisted by the valve. Finally, when only cold air is required in a second extreme state, the valve shuts off the water circuit and the fresh air passage shutter is wide open. 
     This solution is not satisfactory, particularly for economical reasons, because of the high cost of the progressive valve and the significant pressure drops in the liquid which are created by the valve when it is open. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to allow good control over the progressive nature of the temperature for an appreciably lower cost. 
     To do that, provision is made for the complex valve to be replaced by a simple valve, coupled to means of mixing the air from the fresh air passage and from the radiator. 
     More specifically, the subject of the invention is heating and/or air-conditioning apparatus particularly for the cabin of a motor vehicle, having: a chassis within which air flows, this chassis being equipped with an air-blowing means and with a means for cooling and heating the air, which operates using a fluid flowing through it, a member for controlling the heating means, at least one air flow duct communicating with the chassis, and at least one mixing shutter with a variable degree of openness for allowing the air stream towards the duct. 
     In this apparatus, the member controlling the heating means is of the on/off type and the mixing shutter is arranged, in the overall direction of air flow, downstream of the heating member, particularly facing a heating surface of the heating means. 
     Advantageously, in an intermediate position of the air flow through the heating means being shut off, the mixing shutter governs the switching of the member controlling the heating means between the on and off modes. 
     According to a first particular embodiment, the fresh air passage is defined between a wall of the chassis and a side wall of the heating means. The arrangement having the following characteristics: 
     two operating states are considered, a first state in which the heating means (valve open) is on and the mixing shutter opens the fresh air passage to the intermediate position, and a second state in which the heating is off and the shutter pivots beyond the intermediate position to allow additional fresh air to pass through the switched-off heating means (valve closed); 
     when the shutter is in a first extreme position, the control member is in the on position and the shutter closes off the fresh air passage so that the air blown passes only through the heating means to form a hot air stream directed towards the duct; 
     between the first position and the intermediate position of the shutter in the first state, the control member remains in the on position and the shutter allows a variable fresh air stream to pass through the passage according to the orientation of the shutter, and also lets through a hot air stream from the heating means so that these streams mix as they head for the duct; 
     when the shutter reaches the intermediate position, the control member switches to the off position and the shutter prevents air from the heating means from flowing so that the air blown passes only through the fresh air passage; and 
     between the intermediate position and a second extreme position of the shutter in the second state, and in this second position, the control member remains in the off position and the shutter is directed toward the heating means so that additional fresh air passes through the heating means, now off, bound for the duct and adds to the fresh air stream coming from the passage. 
     According to an alternative form of the embodiment: 
     aside from the mixing shutter, the apparatus comprises an additional shutter also arranged downstream of the heating means, so that the two shutters are capable, in a given position, of closing off the flow of air passing through the heating means, and: 
     between a first position and before reaching a second position of the mixing shutter, the first state is defined by the mixing shutter switching from the fresh air passage being closed so that the blown air passes only through the heating means to form a hot air stream bound for the duct, to variable opening of the fresh air passage then in collaboration with the additional shutter so as to allow a hot air stream from the heating means to pass so that these streams mix as they head for the duct; 
     when the mixing shutter reaches the second position, the control member switches to the off position and the additional shutter being arranged in a first closed position, the shutters then collaborate to shut off the flow of air from the heating means so that the air blown passes only through the fresh air passage; and 
     between this first and a second position of the additional shutter, the mixing shutter remaining in its second position and the control member in the off position, the second state is defined by an opening of the air passage through the heating means, now off, which provides additional fresh air bound for the duct and adds to the fresh air stream coming from the fresh air passage. 
     According to another embodiment, a fresh air passage is provided between a wall of the chassis and a side wall of the heating means. The arrangement having the following characteristics: 
     the mixing shutter controls the shutting-off of the air flow through the heating means in a closed position, this flow passage being opened variably outside of this position; 
     the apparatus further comprises an additional shutter arranged in the chassis in such a way as to close off the fresh air passage in a closed position and to open this passage variably outside of this position; 
     the mixing shutter being in the closed position and the additional shutter in the open position, the control member of the heating means is in the off mode and the air blown passes only through the fresh air passage; 
     the mixing and additional shutters being outside of the closed positions, the control member of the heating means is in the on mode and the additional shutter allows a fresh air stream to pass through the passage and the mixing shutter allows a hot air stream from the heating means to pass so that these streams mix as they head for the duct; 
     the mixing shutter being outside of the closed position and the additional shutter in the closed position, the control member is in the on mode so that the blown air passes only through the heating means so as to form a hot air stream bound for the duct; and 
     when the shutters are in the open position, the control member is in the off mode so that additional fresh air passes through the heating means, now off, bound for the duct and adds to the fresh air stream coming from the passage. 
     Another subject of the invention is a vehicle equipped with heating and/or air-conditioning apparatus as described previously. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood and other features, details and advantages thereof will become more clearly apparent from reading the description which follows, given by way of example with reference to the appended drawings in which: 
     FIGS. 1 a ,  1   b  and  1   c  are views in cross section of a heating and/or air-conditioning apparatus according to the invention comprising a mixing shutter depicted in three operating positions; 
     FIGS. 2 a ,  2   b  and  2   c  are views in cross section of a second embodiment of the present invention having an additional shutter depicted in various operating positions; and 
     FIGS. 3 a  and  3   b  are views in cross section of an alternative embodiment of FIGS. 2 a ,  2   b  and  2   c.   
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference is made first of all to FIG. 1 a  to describe a heating and/or air-conditioning apparatus  1  for a motor vehicle cabin. This apparatus  1  includes an outer chassis  10 , for example made of plastic, having an upstream part  12  typically connected to a vehicle dashboard (not depicted) and a downstream part  14  communicating with a duct  16 . 
     An air blowing member  20 , such as a blower, together with an evaporator  22  and a radiator  24 , are mounted one beside the other in the chassis  10 , the evaporator  22  being mounted upstream of the radiator  24  and downstream of the blower  20  in the direction of flow of the air illustrated by the arrow F. 
     The radiator  24  has at least one downstream heating surface  25 . It operates on a fluid such as water flowing through it in such a way as to form an indirect exchanger of heat with the water. It is equipped with a control member  26  of on/off type, such as a valve so as to switch the radiator from off to on and vice versa. 
     A fresh air passage  27  is formed between a wall of the chassis  10  and an edge  28  of the radiator  24  and serves for the flow of air from the evaporator  22  which covers the entire cross section of the chassis  10 . 
     A mixing shutter  30  is arranged facing the heating surface  25  of the radiator  24  and is hinged about an axis xx′ perpendicular to the plane of section of FIG.  1 . 
     In all the examples mentioned hereinafter, the switch in state of the valve is controlled directly by the angular position of the mixing shutter  30 . 
     This shutter  30  can adopt a first extreme position illustrated in FIG. 1 a , a second intermediate position illustrated in FIG. 1 b , and a third extreme position illustrated in FIG. 1 c.    
     In its first extreme position, the mixing shutter  30  shuts off the fresh air passage  27  and governs the valve  26  in such a way that it is in the position of switching the radiator  24  on. Thus, a hot air stream (arrow F 1 ) only passes through the chassis  10  and the radiator  24  bound for the duct  16 . This is the position for maximum heating. 
     Between the first extreme position and the second intermediate position of the mixing shutter  30 , the valve  26  remains in its on position. The fresh air stream F 2  passing through the passage  27  and the hot air stream F 1  from the radiator  24  mix as they head for the duct  16 . This is the position of heating modulated with air the warmth of which varies with the angular position of the shutter  30 . 
     When the shutter  30  reaches the second intermediate position illustrated in FIG. 1 b , it mechanically, or electromechanically with the aid of a relay, governs the switching of the valve  26  from the position in which the radiator  24  is on to the position in which the latter is off. In this position, only the fresh air stream F 2  flows through the duct  16 , the air passing through the radiator being shut off at the shutter  30 . This is the normal fresh air position. 
     Finally, between the second intermediate position and the third extreme position of the shutter  30 , and in this third position illustrated in FIG. 1 c , the valve  26  remains in the off position and the shutter is inclined towards the heating surface  25  of the radiator  24  so that additional fresh air (arrow F 3 ) passes through the radiator, now off, and is added to the fresh air stream F 2  coming from the passage  27 . This is the maximum fresh air position. 
     In FIGS. 2 a  to  2   c , the mixing shutter  30  operates in concert with an additional shutter  32  mounted to pivot about an axis yy′ situated near the wall of the chassis  10 , the additional shutter  32  being arranged facing the downstream heating surface  25  of the radiator  24 , like the mixing shutter  30 . This additional shutter  32  can adopt a first extreme position illustrated in FIGS. 2 a  and  2   b , and a second extreme position illustrated in FIG. 2 c.    
     In FIG. 2 a , the mixing shutter  30  is in its first position in which it shuts off the fresh air passage  27  and governs the valve  26  in such a way that it is in the position that switches the radiator  24  on. Thus, a hot air stream (arrow F 1 ) only passes through the chassis  10  and the radiator  24  bound for the duct  16 . The additional shutter  32  is preferably in its first extreme position, although it may be in its second extreme position. This is the position for maximum heating. 
     Between the first position and the second position of the mixing shutter  30 , the valve  26  remains in its on position. The fresh air stream F 2  passing through the passage  27  and the hot air stream F 1  from the radiator  24  mix as they head for the duct  16 . The position of the additional shutter once again is of little importance here. This is the modulated heating position. 
     When the shutter  30  reaches the second position illustrated in FIG. 2 b  it mechanically, or electromechanically with the aid of a relay, governs the switching of the valve  26  from the position in which the radiator  24  is on to the position in which the latter is off. The additional shutter  32  for its part is in its first extreme position. In this position, only the fresh air stream F 2  from the passage  27  flows through the duct  16 , the air passing through the radiator  24  being shut off at the shutters  30  and  32 . This is the normal fresh air position. 
     Finally, between the first extreme position and the second extreme position of the additional shutter  32 , and in this second position illustrated in FIG. 2 c  and called, the valve  26  remains in the off position and the additional shutter is inclined to some extent towards the heating surface  25  of the radiator  24  so that additional fresh air illustrated by the arrow F 3  passes through the radiator, now off, and is added to the fresh air stream F 2  from the passage  27 . This is the maximum fresh air position. 
     An alliterative form of embodiment, not depicted, includes arranging the axis yy′ of the additional shutter  32  more or less at the end of the mixing shutter  30 , when the latter is in its second position illustrated by FIGS. 2 b  or  2   c.    
     The alternative form of embodiment illustrated in FIGS. 3 a  to  3   c  also involves a mixing shutter  30  and an additional shutter  32 ′. A fresh air passage  27 ′ is arranged between the wall of the chassis  10  and an edge  28 ′ of the radiator  24 , above the radiator  24 . 
     In FIG. 3 a , the mixing shutter is in its first position and the additional shutter  32 ′ is in its second. With the apparatus in this state, the valve  26  is in its position for which the radiator  24  is off and only a fresh air stream (arrow F 2 ) passes through the passage  27 ′ bound for the duct  16 . This is the normal fresh air function. 
     When the mixing shutter leaves its first position and lies between this position and the second position (dotted lines in FIG. 3 a ), the control member  26  switches to the position of switching the radiator  24  on and a hot air stream therefore passes through the radiator and mixes with the fresh air stream F 2  passing through the passage. Orientating the mixing shutter  30  makes it possible to adjust the hot air/fresh air mix bound for the duct  16 . This is the modulated heating function. 
     When the mixing shutter switches to its second position illustrated in FIG. 3 b , the control member switches to its position in which the radiator  24  is off. A fresh air stream F 3  then adds to the fresh air stream F 2  from the passage  27 ′. This additional fresh air passing through the radiator  24 , now off, makes it possible to increase the rate of flow of fresh air through the duct  16 . This is the maximum fresh air function. 
     Finally, if the additional shutter  32 ′ switches to its first position of shutting off the passage  27 ′, which position is illustrated in FIG. 3 c , and the mixing shutter  30  fluctuates between its first and second positions, only the hot air stream F 1  from the radiator reaches the duct. This is the maximum heating function, the air flow rate of which depends on the angular position of the first shutter. 
     By virtue of the solutions put forward, the progressive nature in terms of temperature of the heating and/or air-conditioning apparatus is better mastered and a fresh air flow rate which is higher than in the prior art comes through the duct  16  by virtue of the maximum fresh air function. 
     The pressure drops in the heating fluid are minimal. There is no parasitic heating when the valve  26  is in its off position and the additional fresh air is sent to the duct  16 . 
     Thus, replacing an elaborate, expensive and more complicated valve with a simple economical valve of the on/off type and positioning one or more mixing shutters in suitable positions make this solution simple to implement, reliable, and less expensive than the solutions of the prior art. 
     While the foregoing invention has been shown and described with reference to a preferred embodiment, it will be understood by those possessing skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. For example, it is possible, using a central unit, to manage the various modes of operation of the shutters, controlled for example by suitable software. Furthermore, the radiator could be of the electric or catalysis type. The person skilled in the art will be able to adapt any type of shutter, for example of the butterfly valve or flag valve type, or shut-off valve, to implement the invention. Thus, the axes of rotation of certain shutters may be offset so that they are placed either at their middle, or at one of their ends, depending on their position and on the angular travel they are to have.