Patent Description:
The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment.

It is known a fluid system including a <NUM>-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 <NUM> ways valve in front of the high pressure drop branch is almost fully open (and the orifice of the <NUM> 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 <NUM> 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.

A conventional fluid circuit according to the preamble of claim <NUM> is known from <CIT>.

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 according to claim <NUM>.

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 <NUM>-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 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.

The present invention will be described with reference to <FIG>, <FIG>. The invention relates to a fluid circuit comprising a three-way valve <NUM>. The three-way valve <NUM> comprises a central channel <NUM>, an inlet port <NUM>, constituting the first path, a first <NUM> and a second <NUM> outlet ports constituting the second and third paths. According to the invention, the first port <NUM> is arranged between the inlet port <NUM> and the second port <NUM> in the direction of flow of the fluid in the three-way valve. In a manner known per se, the first outlet orifice <NUM> is connected to a first component (not shown) of the fluid circuit and the second orifice <NUM> 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 <NUM>, which is lower than the pressure drop generated by the second component in the second port <NUM>. By way of example, the fluid circuit according to FIG. invention is a cooling circuit. The second port <NUM> of the three-way valve is to a heat exchanger and the first port <NUM> is connected to a branch bypassing the heat exchanger.

The three-way valve <NUM> comprises an adjustment device <NUM>, <NUM>, <NUM> the opening / closing of the first / second orifices <NUM>, <NUM>. According to the invention, the adjustment device <NUM>, <NUM><NUM> simultaneously ensures the closing of the first orifice <NUM> and the opening of the second orifice <NUM> and vice versa. In other words, when the adjustment device <NUM>, <NUM>, <NUM> is in a closed position of the first port <NUM>, the adjustment device <NUM>, <NUM>, <NUM> is in an open position of the second port <NUM> and conversely.

In order to compensate for the difference in pressure drop generated in the first and second ports <NUM>, <NUM> of the three-way valve <NUM>, the adjustment device <NUM>, <NUM>, <NUM> comprises a closure element for the first port ensuring faster closing of the first port <NUM> relative to the opening speed of the second port <NUM>. In other words, when the first port <NUM> is closed and the second port <NUM> is opened simultaneously, the passage section of the first port <NUM> will decrease more rapidly than the increase in the passage section of the second orifice <NUM>.

According to a first variant embodiment shown in <FIG>, the adjustment device comprises a first piston <NUM> mounted in the channel <NUM> of the three-way valve <NUM>. The first piston <NUM> 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 <NUM>.

The first piston <NUM> comprises a first window <NUM> and a second window <NUM>. The first window <NUM> is provided to come opposite the first orifice <NUM> when the three-way valve <NUM> is in the open position of the first orifice and the second window <NUM> is designed to come opposite the second orifice <NUM> when the three-way valve <NUM> is in the open position of the second orifice <NUM>. In operation, the fluid circulates in the first piston <NUM> then through of the first and / or second window <NUM>, <NUM> depending on the position of the first piston <NUM> in the channel <NUM>.

According to the first variant, the first piston <NUM> is slidably mounted in the channel <NUM> of the three-way valve <NUM>. The translational movement of the first piston <NUM> is provided by an actuator (not shown) known per se of the solenoid type. A first elastic element <NUM> is mounted between the first piston <NUM> and the channel <NUM> to return the first piston to an initial position where the first window <NUM> is opposite the first orifice <NUM> and the second orifice <NUM> is closed. Thus, when the actuator is actuated, the first piston <NUM> is moved to a position where the second window <NUM> is opposite the second port <NUM> and the first port <NUM> is closed. When the actuator is deactivated, the first elastic element <NUM> returns the piston to the initial position.

The adjustment device further comprises a second piston <NUM> mounted in the first piston <NUM>. The second piston <NUM> 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 <NUM>.

The second piston <NUM> comprises a first window <NUM> and a second window <NUM>. The first window <NUM> is provided to come opposite the first orifice <NUM> when the three-way valve <NUM> is in the open position of the first orifice and the second window <NUM> is provided to come opposite the second orifice <NUM> when the three-way valve <NUM> is in the open position of the second orifice <NUM>. In operation, the fluid circulates in the second piston <NUM> then through of the first and / or second window <NUM>, <NUM> depending on the position of the first piston <NUM> in the channel <NUM>. According to the invention, the dimensions of the first window <NUM> of the second piston <NUM> are substantially the same as the first window <NUM> of the first piston <NUM>. The dimensions of the second window <NUM> of the second piston <NUM> are larger than the dimensions of the second window <NUM> of the first piston <NUM>. Furthermore, a second elastic means <NUM> is mounted between the first and the second piston <NUM>, <NUM> to return the second piston to an initial position where the first window <NUM> of the second piston is facing the first orifice <NUM> and the second port <NUM> is closed. The elasticity of the second elastic element <NUM> is provided so that the second piston <NUM> moves faster than the first piston <NUM> when the first port <NUM> is closed. Thus, the passage section of the first port <NUM> of the three-way valve closes faster than the second port <NUM> 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 <NUM> and the second <NUM> orifices generated during the circulation of the fluid. Indeed, the pressure drop generated in the first orifice <NUM> is lower than that generated in the second orifice <NUM>. The smaller passage section of the first orifice <NUM> will allow a flow of fluid in the second origin <NUM> in which is generated greater pressure drop.

<FIG> illustrates the initial position of the three-way valve <NUM> according to the invention in which the first port <NUM> is open and the second port <NUM> is closed. In this position, the first windows <NUM>, <NUM> of the first and second piston <NUM>, <NUM> are facing the first orifice <NUM>. The first windows <NUM>, <NUM> of the first and second piston <NUM>, <NUM> are aligned. The second windows <NUM>, <NUM> of the first and second piston <NUM>, <NUM> are offset from the second orifice <NUM>.

<FIG> represents an intermediate position of the three-way valve <NUM> in which the actuator has started to move the first piston <NUM> towards the open position of the second port <NUM>. In this intermediate position, the first window <NUM> of the first piston <NUM> shifts and the first piston partially closes the first orifice <NUM>. The second window <NUM> of the first piston <NUM> begins to align with the second orifice <NUM>, then increasing the passage section of the second orifice <NUM>. At the same time, the second piston <NUM> obstructs part of the first window <NUM> of the first piston <NUM>, then reducing the passage section of the first orifice <NUM> relative to the passage section of the second orifice <NUM>.

<FIG> illustrates the final position of the three-way valve <NUM> according to the invention in which the first port <NUM> is closed and the second port <NUM> is open. In this position, the second windows <NUM>, <NUM> of the first and second piston <NUM>, <NUM> are opposite the second orifice <NUM>. The second windows <NUM>, <NUM> of the first and second piston <NUM>, <NUM> are opposite screw from to the second port <NUM>. The second windows <NUM>, <NUM> of the first and second piston <NUM>, <NUM> are aligned.

Sealing elements (not shown) (of the seal or lip type) are positioned between the channel <NUM> and the first piston <NUM> and between the first piston <NUM> and the second piston <NUM> in order to prevent fluid leaks. The first and second elastic means are coil springs.

According to a second variant embodiment shown in <FIG>, 3B, the second piston <NUM> is replaced by a shutter <NUM>. The shutter <NUM> is pivotally mounted on the edge of the first window <NUM> of the first piston <NUM>. The shutter <NUM> is arranged to open or close the first window <NUM> of the first piston <NUM> during the movement of the first piston. The dimensions of the shutter <NUM> correspond to the dimensions of the first window <NUM> of the first piston <NUM>. The pivoting of the shutter <NUM> is for example provided by a hinge <NUM> positioned on the edge of the first window <NUM> furthest from the inlet orifice <NUM> of the three-way valve <NUM>.

<FIG> illustrates the initial position of the three-way valve <NUM> according to the invention in which the first port <NUM> is open and the second port <NUM> is closed. In this opening position of the first window <NUM>, the shutter <NUM> enters the first orifice <NUM>. The shutter <NUM> does not interfere with the flow of fluid in the first orifice <NUM>. The second orifice <NUM> being closed by the first piston <NUM>, the entire fluid flow passes through the first orifice <NUM>.

<FIG> represents an intermediate position of the three-way valve <NUM> in which the actuator has started to move the first piston <NUM> towards the open position of the second port <NUM>. When moving the first piston <NUM> in the opening direction from the second orifice <NUM>, the shutter <NUM> is moved by the wall of the first orifice <NUM> to partially obstruct the first window <NUM> of the first piston. The junction between the wall of the orifice and the channel <NUM> of the three-way valve <NUM> may have a radius of curvature to ensure progressive pivoting of the shutter <NUM>. The second window <NUM> of the first piston <NUM> begins to align with the second orifice <NUM> then increasing the passage section of the second orifice <NUM>. However, in this position, the passage section of the first window <NUM> is reduced by the shutter <NUM> relative to the passage section of the second window <NUM>. This difference in passage section in favor of the second window <NUM> makes it possible to balance the flow of fluid between the two orifices <NUM>, <NUM> without modifying the flow entering the three-way valve.

<FIG> illustrates the final position of the three-way valve <NUM> according to the invention in which the first port <NUM> is closed and the second port <NUM> is open. In this position, the shutter <NUM> is held in the closed position of the first window <NUM> by the wall of the channel <NUM>. The second window <NUM> of the first piston <NUM> faces the second orifice <NUM>. In this position, the entire flow passes through the second port <NUM>.

According to an alternative embodiment not shown, an assembly is rotation of the first piston <NUM> and / or of the second piston <NUM> is also possible.

Claim 1:
Fluid circuit comprising a <NUM>-way valve (<NUM>) comprising a central channel (<NUM>) into which opens an inlet port (<NUM>), a first outlet port (<NUM>) and a second outlet port (<NUM>), the <NUM>-way valve further comprising an adjustment device (<NUM>, <NUM>, <NUM>) simultaneously ensuring the opening, respectively the closing of the first outlet port (<NUM>) and the closing respectively the opening of the second outlet port (<NUM>) so that the closing speed of the first outlet port (<NUM>) is faster than the opening speed of the second outlet port (<NUM>), characterized in that 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 <NUM>-way valve being lower than the pressure drop generated by the second component in the <NUM>-way valve.