Patent Publication Number: US-2022228668-A1

Title: Fluid circuit for a motor vehicle

Description:
TECHNICAL FIELD 
     The invention concerns a fluid circuit for a motor vehicle and more particularly a fluid circuit comprising a 3-way valve. The fluid circuit according to the invention can be applied to any type of fluid, including a cooling circuit. 
     The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment. 
     BACKGROUND 
     It is known a fluid system including a 3-way valve managing the flow in a branch with a heat exchanger and a branch for the exchanger by-pass (the by-pass branch usually has a much lower pressure drop than the heat exchanger branch) such as automotive coolant thermostat or oil thermostat. In such a system, it requires that the orifice of the 3 ways valve in front of the high pressure drop branch is almost fully open (and the orifice of the 3 ways valve in front of the low pressure drop branch is almost fully closed) to get a flow in the high pressure drop branch that is significant. 
     In other words, it takes a long stroke of the valve piston to starts to reduce significantly the flow in the low-pressure drop branch/increase significantly the flow in the high-pressure drop branch. Therefore, regulation of the flow in the 2 branches is only done along a small part of the piston stroke, which can make a control very difficult. 
     In view to reduce this drawback it is known solution to increase permanently the pressure drop of the so-called “low pressure drop branch” which ends in an overall increase of the complete system pressure drop, whatever the position of the piston valve (fully close, fully open, or any position in-between). This has a negative impact on the pump, which then absorb power and so increase the fuel consumption 
     SUMMARY 
     An object of the invention is to provide a fluid circuit managing drop pressure difference between two ducts connected to a three-way valve without increasing fuel consumption. 
     This is achieved by a fluid circuit comprising a 3-way valve, the 3-way valve comprises a central channel into which an inlet port, a first outlet port and a second outlet port open, the 3-way valve comprises an adjustment device which simultaneously opens, respectively closes the first port and closes respectively opens so that the closing speed of the first port is faster than the opening speed of the second port. 
     The difference in opening/closing of the two ports allows having a progressive pressure drop of the system along the stroke of the valve. If only a simple valve was used, the pressure drop would suddenly change when the low-pressure drop channel will open and a high flow will suddenly raise in this low-pressure drop channel. The other drawback of the simple valve solution lead to a low flow in the partially opened high-pressure drop channel and then, a sudden flow increase when the low-pressure drop channel will close. The behavior of such a simple valve is then hard to control, because the flows are inverting very quickly in a very small range of stroke of the valve. 
     According to another embodiment, the adjustment device comprises a first piston mounted coaxially in the central channel, the piston comprises a first window and a second window, the first respectively second window being arranged to ensure the opening of the first respectively second orifice, the first window being equipped in a flap actuated by the movement of the first piston and ensuring the at least partial closing of the first orifice of the 3-way valve. 
     According to another embodiment, the adjustment device comprises a first piston mounted coaxially in the central channel, the first piston comprises a first window and a second window, the first respectively second window being arranged so as to ensure the opening of the first respectively second orifice, the opening device comprises a second piston mounted coaxially in the first piston the second piston comprises a first window and a second window, the first window being arranged so as to partially close the first window of the first piston when the first orifice is closed by the first piston. 
     In another embodiment, the first piston is slidably mounted in the central channel and comprises an elastic element for returning it to a position closing the second orifice. 
     Alternatively, the second piston is slidably mounted in the first piston and has an elastic return element to return it to a position where the first window of the first piston is partially closed. 
     According to another embodiment, an actuator arranged to cause the first piston to move between a first position in which the first port is closed and the second port is open and a second position in which the first port is open and the second port is closed. 
     According to another embodiment, the fluid circuit is a cooling circuit comprising a first component connected to the first outlet port and a second component connected to the second outlet port, the pressure drop generated by the first component in the 3-way valve is lower than the pressure drop generated by the second component in the 3-way valve. 
     According to another embodiment, the fluid circuit is a cooling circuit comprising a heat exchanger and a heat exchanger bypass circuit, the first outlet port being connected to the heat exchanger bypass circuit and the second outlet port being connected to the heat exchanger 
     In case of a cooling system, the cooler being the high pressure drop channel and the by-pass the low pressure drop channel, the actuator might be a thermostat. For a wax thermostat, the invention will enable the highest regulated temperature. For an electrical thermostat, the controller will be easy to define, and its associated data set will ensure an accurate position of the valve. 
     Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples. 
       In the drawings: 
         FIG. 1A, 1B, 1C  shows a schematic view of a first embodiment of a 3-way valve of the fluid circuit according to the invention in three different operating positions. 
         FIG. 2A, 2B, 2C  shows a schematic view of a second embodiment of a 3-way valve of the fluid circuit according to the invention in three different operating positions. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION 
     The present invention will be described with reference to  FIGS. 1A, 1B, 1C, 2A, 2B, 2C . The invention relates to a fluid circuit comprising a three-way valve  1 . The three-way valve  1  comprises a central channel  13 , an inlet port  10 , constituting the first path, a first  11  and a second  12  outlet ports constituting the second and third paths. According to the invention, the first port  11  is arranged between the inlet port  10  and the second port  12  in the direction of flow of the fluid in the three-way valve. In a manner known per se, the first outlet orifice  11  is connected to a first component (not shown) of the fluid circuit and the second orifice  12  is connected to a second component (not shown) of the fluid circuit. According to the invention, the first component generates a pressure drop at the level of the first port  11 , which is lower than the pressure drop generated by the second component in the second port  12 . By way of example, the fluid circuit according to FIG. invention is a cooling circuit. The second port  12  of the three-way valve is to a heat exchanger and the first port  11  is connected to a branch bypassing the heat exchanger. 
     The three-way valve  1  comprises an adjustment device  2 ,  3 ,  4  the opening/closing of the first/second orifices  11 ,  12 . According to the invention, the adjustment device  2 ,  3   4  simultaneously ensures the closing of the first orifice  11  and the opening of the second orifice  12  and vice versa. In other words, when the adjustment device  2 ,  3 ,  4  is in a closed position of the first port  11 , the adjustment device  2 ,  3 ,  4  is in an open position of the second port  12  and conversely. 
     In order to compensate for the difference in pressure drop generated in the first and second ports  11 ,  12  of the three-way valve  1 , the adjustment device  2 ,  3 ,  4  comprises a closure element for the first port ensuring faster closing of the first port  11  relative to the opening speed of the second port  12 . In other words, when the first port  11  is closed and the second port  12  is opened simultaneously, the passage section of the first port  11  will decrease more rapidly than the increase in the passage section of the second orifice  12 . 
     According to a first variant embodiment shown in  FIGS. 1A, 1B, 1C , the adjustment device comprises a first piston  2  mounted in the channel  13  of the three-way valve  1 . The first piston  2  is hollow open at a first end and closed at the second end. The first end is located at the inlet of the three-way valve  1 . 
     The first piston  2  comprises a first window  21  and a second window  22 . The first window  21  is provided to come opposite the first orifice  11  when the three-way valve  1  is in the open position of the first orifice and the second window  22  is designed to come opposite the second orifice  12  when the three-way valve  1  is in the open position of the second orifice  12 . In operation, the fluid circulates in the first piston  2  then through of the first and/or second window  21 ,  22  depending on the position of the first piston  2  in the channel  13 . 
     According to the first variant, the first piston  2  is slidably mounted in the channel  13  of the three-way valve  1 . The translational movement of the first piston  2  is provided by an actuator (not shown) known per se of the solenoid type. A first elastic element  6  is mounted between the first piston  2  and the channel  13  to return the first piston to an initial position where the first window  21  is opposite the first orifice  11  and the second orifice  12  is closed. Thus, when the actuator is actuated, the first piston  2  is moved to a position where the second window  22  is opposite the second port  12  and the first port  11  is closed. When the actuator is deactivated, the first elastic element  6  returns the piston to the initial position. 
     The adjustment device further comprises a second piston  3  mounted in the first piston  2 . The second piston  3  is hollow open at a first end and closed at the second end. The first end is located at the inlet of the three-way valve  1 . 
     The second piston  3  comprises a first window  31  and a second window  32 . The first window  31  is provided to come opposite the first orifice  11  when the three-way valve  1  is in the open position of the first orifice and the second window  32  is provided to come opposite the second orifice  12  when the three-way valve  1  is in the open position of the second orifice  12 . In operation, the fluid circulates in the second piston  3  then through of the first and/or second window  31 ,  32  depending on the position of the first piston  2  in the channel  13 . According to the invention, the dimensions of the first window  31  of the second piston  3  are substantially the same as the first window  21  of the first piston  2 . The dimensions of the second window  32  of the second piston  3  are larger than the dimensions of the second window  22  of the first piston  2 . Furthermore, a second elastic means  5  is mounted between the first and the second piston  2 ,  3  to return the second piston to an initial position where the first window  31  of the second piston is facing the first orifice  11  and the second port  12  is closed. The elasticity of the second elastic element  5  is provided so that the second piston  3  moves faster than the first piston  2  when the first port  11  is closed. Thus, the passage section of the first port  11  of the three-way valve closes faster than the second port  12  of the three-way valve opens. This difference in passage section then makes it possible to compensate for the difference in pressure drop between the first  11  and the second  12  orifices generated during the circulation of the fluid. Indeed, the pressure drop generated in the first orifice  11  is lower than that generated in the second orifice  12 . The smaller passage section of the first orifice  11  will allow a flow of fluid in the second origin  12  in which is generated greater pressure drop. 
       FIG. 1A  illustrates the initial position of the three-way valve  1  according to the invention in which the first port  11  is open and the second port  12  is closed. In this position, the first windows  21 ,  31  of the first and second piston  2 ,  3  are facing the first orifice  11 . The first windows  21 ,  31  of the first and second piston  2 ,  3  are aligned. The second windows  22 ,  32  of the first and second piston  2 ,  3  are offset from the second orifice  12 . 
       FIG. 1B  represents an intermediate position of the three-way valve  1  in which the actuator has started to move the first piston  2  towards the open position of the second port  12 . In this intermediate position, the first window  21  of the first piston  2  shifts and the first piston partially closes the first orifice  11 . The second window  22  of the first piston  2  begins to align with the second orifice  12 , then increasing the passage section of the second orifice  12 . At the same time, the second piston  3  obstructs part of the first window  21  of the first piston  2 , then reducing the passage section of the first orifice  11  relative to the passage section of the second orifice  12 . 
       FIG. 1C  illustrates the final position of the three-way valve  1  according to the invention in which the first port  11  is closed and the second port  12  is open. In this position, the second windows  22 ,  32  of the first and second piston  2 ,  3  are opposite the second orifice  12 . The second windows  22 ,  32  of the first and second piston  2 ,  3  are opposite screw from to the second port  12 . The second windows  22 ,  32  of the first and second piston  2 ,  3  are aligned. 
     Sealing elements (not shown) (of the seal or lip type) are positioned between the channel  13  and the first piston  2  and between the first piston  2  and the second piston  3  in order to prevent fluid leaks. The first and second elastic means are coil springs. 
     According to a second variant embodiment shown in  FIGS. 2A, 2B, 3B , the second piston  2  is replaced by a shutter  4 . The shutter  4  is pivotally mounted on the edge of the first window  21  of the first piston  2 . The shutter  4  is arranged to open or close the first window  21  of the first piston  2  during the movement of the first piston. The dimensions of the shutter  4  correspond to the dimensions of the first window  21  of the first piston  2 . The pivoting of the shutter  4  is for example provided by a hinge  41  positioned on the edge of the first window  11  furthest from the inlet orifice  10  of the three-way valve  1 . 
       FIG. 2A  illustrates the initial position of the three-way valve  1  according to the invention in which the first port  11  is open and the second port  12  is closed. In this opening position of the first window  21 , the shutter  4  enters the first orifice  11 . The shutter  4  does not interfere with the flow of fluid in the first orifice  11 . The second orifice  12  being closed by the first piston  1 , the entire fluid flow passes through the first orifice  11 . 
       FIG. 2B  represents an intermediate position of the three-way valve  1  in which the actuator has started to move the first piston  2  towards the open position of the second port  12 . When moving the first piston  2  in the opening direction from the second orifice  12 , the shutter  4  is moved by the wall of the first orifice  11  to partially obstruct the first window  11  of the first piston. The junction between the wall of the orifice and the channel  13  of the three-way valve  1  may have a radius of curvature to ensure progressive pivoting of the shutter  4 . The second window  22  of the first piston  2  begins to align with the second orifice  12  then increasing the passage section of the second orifice  12 . However, in this position, the passage section of the first window  21  is reduced by the shutter  4  relative to the passage section of the second window  22 . This difference in passage section in favor of the second window  22  makes it possible to balance the flow of fluid between the two orifices  11 ,  12  without modifying the flow entering the three-way valve  1 . 
       FIG. 1C  illustrates the final position of the three-way valve  1  according to the invention in which the first port  11  is closed and the second port  12  is open. In this position, the shutter  4  is held in the closed position of the first window  21  by the wall of the channel  13 . The second window  22  of the first piston  2  faces the second orifice  12 . In this position, the entire flow passes through the second port  12 . 
     According to an alternative embodiment not shown, an assembly is rotation of the first piston  2  and/or of the second piston  3  is also possible. 
     It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.