阅读说明：本技术 流体回路和用于控制供应到至少一个设备的流体流的方法 (Fluid circuit and method for controlling a fluid flow supplied to at least one device ) 是由 纪尧姆·马尔索 尼古拉斯·格拉诺捷 于 2017-12-29 设计创作，主要内容包括：本发明涉及一种流体回路(3),其包括：-供应管线(5),用于将流体从连接到流体箱(2)的泵(4)输送到设备(8),所述供应管线具有以下部分,该部分被分成包括热交换器(13)的主管线(10)和用于旁通所述热交换器的旁通管线(15)；-第一阀(31)和第一控制装置(33),所述第一阀用于控制主管线(10)中和旁通管线(15)中的相应流体流,所述第一控制装置用于根据流体的第一参数(T)来控制第一阀(31)；-压力调节回路,用于将流体从供应管线(5)朝向流体箱(2)输送,所述压力调节回路包括压力调节阀(23),用于控制被引导回流体箱(2)的流体流；其中,所述压力调节回路包括：-第一再循环管线(21),其在旁通管线出口(17)的下游从供应管线(5)分支；-第二再循环管线(22),其在旁通管线入口(16)的上游从供应管线(5)分支；-第二阀(32)和第二控制装置(33),所述第二阀用于控制第一再循环管线(21)中和第二再循环管线(22)中的相应流体流,所述第二控制装置用于根据流体的第二参数(T)来控制第一阀(31)。(The invention relates to a fluid circuit (3) comprising: -a supply line (5) for conveying fluid from a pump (4) connected to a fluid tank (2) to a device (8), the supply line having a portion that is divided into a main line (10) comprising a heat exchanger (13) and a bypass line (15) for bypassing the heat exchanger; -a first valve (31) for controlling a respective fluid flow in the main line (10) and in the bypass line (15), and a first control device (33) for controlling the first valve (31) as a function of a first parameter (T) of the fluid; -a pressure regulating circuit for conveying fluid from the supply line (5) towards the fluid tank (2), the pressure regulating circuit comprising a pressure regulating valve (23) for controlling the flow of fluid directed back to the fluid tank (2); wherein the pressure regulating circuit comprises: -a first recirculation line (21) branching off from the supply line (5) downstream of the bypass line outlet (17); -a second recirculation line (22) branching off from the supply line (5) upstream of the bypass line inlet (16); -a second valve (32) for controlling a respective fluid flow in the first recirculation line (21) and in the second recirculation line (22), and second control means (33) for controlling the first valve (31) as a function of a second parameter (T) of the fluid.)

1. A fluid circuit (3) comprising:

-a supply line (5), the supply line (5) being for conveying fluid from a pump (4) connected to a fluid tank (2) to at least one device (8), a portion of the supply line (5) being divided into a main line (10) and a bypass line (15), the main line (10) comprising a heat exchanger (13), the bypass line (15) being for bypassing the heat exchanger (13), the main line (10) and the bypass line (15) being arranged in parallel and each having an inlet (11, 16) and an outlet (12, 17);

-a first valve (31) and a first control device (33), the first valve (31) being adapted to control a respective fluid flow in the main line (10) and in the bypass line (15), the first control device (33) being adapted to control the first valve (31) in dependence of a first parameter (T) of the fluid;

-a pressure regulating circuit for conveying the fluid from the supply line (5) towards the fluid tank (2), the pressure regulating circuit comprising a pressure regulating valve (23), the pressure regulating valve (23) being for controlling the fluid flow directed back to the fluid tank (2);

wherein the pressure regulating circuit comprises:

-a first recirculation line (21), said first recirculation line (21) branching off from said supply line (5) downstream of said outlet (17) of said bypass line, for conveying said fluid from said supply line (5) towards said fluid tank (2);

-a second recirculation line (22), said second recirculation line (22) branching off from said supply line (5) upstream of said inlet (16) of said bypass line, for conveying said fluid from said supply line (5) towards said fluid tank (2);

-a second valve (32) and second control means (33), the second valve (32) being for controlling a respective fluid flow in the first recirculation line (21) and in the second recirculation line (22), the second control means (33) being for controlling the second valve (32) in dependence of a second parameter (T) of the fluid.

2. The fluid circuit of claim 1, wherein at least one of the first parameter and the second parameter of the fluid is a fluid temperature (T).

3. The fluid circuit according to claim 1 or 2, characterized in that at least one of said first and second parameters of said fluid is the fluid temperature (T) in said supply line (5), preferably downstream of said outlet (17) of said bypass line.

4. A fluid circuit according to any one of claims 1 to 3, characterized in that said first parameter (T) and said second parameter (T) are one and the same.

5. The fluid circuit according to any one of claims 1 to 4, characterized in that the first and second control means (33) are configured to synchronize the displacement of the first and second valves (31, 32).

6. The fluid circuit according to claims 4 and 5, characterized in that said first control means and said second control means (33) are one and the same.

7. Fluid circuit according to claim 6, characterised in that said first valve (31) and said second valve (32) comprise one and the same body forming a movable member of one and the same valve device (30).

8. The fluid circuit according to any one of claims 1 to 7, characterized in that the first valve (31) is arranged upstream of the heat exchanger (13).

9. The fluid circuit according to any one of claims 1 to 7, characterized in that the first valve (31) is arranged downstream of the heat exchanger (13).

10. The fluid circuit according to any one of claims 1 to 9, characterized in that the first valve (31) is a three-way valve.

11. The fluid circuit according to any one of claims 1 to 9, characterized in that the first valve (31) is a two-way valve arranged in the bypass line (15).

12. The fluid circuit according to any one of claims 1 to 11, characterized in that the pressure regulating valve (23) comprises a first passage (25) for the first recirculation line (21) and a second passage (26) for the second recirculation line (22), the pressure regulating valve (23) being movable between a closed position, in which both the first passage (25) and the second passage (26) are closed, and an open position, in which both the first passage (25) and the second passage (26) are open.

13. A fluid system comprising a fluid circuit (3) according to any one of the preceding claims, and further comprising a fluid tank (2) and a constant displacement pump (4) arranged between the fluid tank (2) and a supply line inlet (6).

14. Vehicle, in particular industrial vehicle, such as a truck, bus or construction vehicle, comprising an engine and a fluid system (3) according to claim 13, wherein the fluid is oil, the vehicle further comprising at least one device (8), such as a vehicle device lubricated by the fluid, a vehicle device cooled by the fluid or a vehicle device moved by the fluid.

15. A method for controlling a flow of fluid supplied from a fluid tank (2) to at least one device (8) by means of a constant displacement pump (4) and a supply line (5), a portion of the supply line (5) being divided into a main line (10) and a bypass line (15), the main line (10) comprising a heat exchanger (13), the bypass line (15) being for bypassing the heat exchanger (13), the main line (10) and the bypass line (15) being arranged in parallel and both having an inlet (11, 16) and an outlet (12, 17), wherein the method comprises:

-monitoring a first parameter (T) of the fluid and controlling a respective fluid flow in the main line (10) and in the bypass line (15) as a function of the first parameter (T);

-monitoring a second parameter (T) of the fluid;

-controlling a fluid return flow directed from the supply line (5) back to the fluid tank (2) as a function of a fluid pressure (P), and controlling respective fluid flows delivered back from a region of the supply line (5) (i) downstream of the outlet (17) of the bypass line and (ii) upstream of the inlet (16) of the bypass line as a function of the second parameter (T).

16. Method according to claim 15, wherein at least one of the first and second parameter of the fluid is a fluid temperature (T), preferably a fluid temperature in the supply line (5) or in the fluid tank (2).

17. The method according to claim 15 or claim 16, characterized in that said first parameter and said second parameter (T) are one and the same.

18. Method according to any of claims 15 to 17, characterized in that the following steps are performed synchronously: a step of controlling the respective fluid flows in the main line (10) and in the bypass line (15) as a function of the first parameter (T); and a step of controlling, as a function of said second parameter (T), the respective fluid flows delivered back from a region of said supply line (5) (i) downstream of said outlet (17) of said bypass line and (ii) upstream of said inlet (16) of said bypass line.

19. Method according to any one of claims 15 to 18, wherein the second parameter is a fluid temperature (T), preferably a fluid temperature in the supply line (5) or in the fluid tank (2), and wherein the heat exchanger (13) is a cooler, characterized in that the fluid which is led back to the fluid tank (2) is only led from a region of the supply line (5) which is upstream of the inlet (16) of the bypass line when it is determined that a part of the fluid has to be led back to the fluid tank (2) due to the fluid pressure (P), and when the fluid temperature (T) is below a first predetermined threshold value (T3).

20. Method according to any one of claims 15 to 19, wherein the second parameter is a fluid temperature, preferably a fluid temperature in the supply line (5) or in the fluid tank (2), and wherein the heat exchanger (13) is a cooler, characterized in that the fluid which is led back to the fluid tank (2) is only led from a region of the supply line (5) downstream of the outlet (17) of the bypass line when it is determined that a part of the fluid has to be led back to the fluid tank (2) due to the fluid pressure, and when the fluid temperature is above a second predetermined threshold value (T5).

Technical Field

The present invention relates to a fluid circuit, a fluid system comprising such a fluid circuit and a vehicle comprising such a fluid system. The invention also relates to a method for controlling a fluid flow supplied from a fluid tank to at least one device.

The invention may be applied to light, medium and heavy vehicles such as trucks, buses and construction equipment, and more generally to any vehicle equipped with an internal combustion engine, including ships and airplanes.

Background

Fluid systems are used in a wide range of technical fields and applications. For example, vehicles often include a fluid system for delivering oil to various devices of the vehicle to lubricate, cool, or move the devices.

Such fluid systems typically include a fluid tank, a pump, and a supply line for delivering fluid to the device. The supply line typically includes a heat exchanger to control the temperature of the fluid provided to the device.

When the pump is a fixed displacement pump, the pump provides the same flow at a given speed, and the currently required fluid pressure may be lower. This results in unnecessarily high fuel consumption. To limit this drawback, without using a more complex and therefore more expensive pump (for example a recirculation pump or a variable capacity pump), a portion of the fluid provided by this pump can be directed back to the tank instead of being supplied to the apparatus. To this end, a portion of the fluid leaving the heat exchanger is led back to the fluid tank, and the fluid return flow can be controlled by the fluid pressure.

However, known fluid systems are not entirely satisfactory, as they still entail significant pressure losses and, therefore, waste of energy.

Disclosure of Invention

It is an object of the present invention to provide a fluid circuit and a method for controlling a fluid flow supplied by such a fluid circuit which improve the known solutions, in particular with respect to energy consumption.

To this end, according to a first aspect, the invention relates to a fluid circuit comprising:

-a supply line for conveying fluid from a pump connected to a fluid tank to at least one device, a portion of the supply line being divided into a main line comprising a heat exchanger and a bypass line for bypassing the heat exchanger, the main line and the bypass line being arranged in parallel and each having an inlet and an outlet;

-a first valve for controlling a respective fluid flow in the main line and in the bypass line, and a first control device for controlling the first valve in dependence on a first parameter of the fluid;

-a pressure regulating circuit for conveying fluid from the supply line towards a fluid tank, the pressure regulating circuit comprising a pressure regulating valve for controlling the fluid flow directed back to the fluid tank;

wherein, this pressure regulation return circuit includes:

-a first recirculation line branching off from the supply line downstream of the outlet of the bypass line for conveying fluid from the supply line towards a fluid tank;

-a second recirculation line branching off from the supply line upstream of the inlet of the bypass line for conveying fluid from the supply line towards a fluid tank;

-a second valve for controlling the respective fluid flows in the first and second recirculation lines, and second control means for controlling the second valve in dependence of a second parameter of the fluid.

The invention thus makes it possible, under some operating conditions corresponding to the pressure and the second parameter of the fluid, to redirect (deviate) the fluid before it enters the heat exchanger, so as to lead it back to the tank. This allows a significant reduction in pressure losses, i.e. the loss of absorbed torque on the pump shaft, and ultimately a reduction in energy consumption.

In other words, when the pump capacity is higher than the current demand, and when it is determined that the entire fluid flow provided by the pump does not need to pass through the heat exchanger to reach the proper operating conditions, at least a portion of the fluid is prevented from entering the heat exchanger as a high pressure drop component.

Another advantage of the present invention is that it allows to implement a heat exchanger with a smaller capacity, thus reducing the costs of the whole fluid circuit. This further improves the overall efficiency, since the efficiency of the heat exchanger is better when the fluid flow through the heat exchanger is higher. In the fluid circuit of the invention, the heat exchanger may be a fluid cooler.

Thanks to the invention, the temperature and pressure management of the fluid circuit is greatly improved, since the fluid supplied to the apparatus has a flow rate that meets the current apparatus requirements, but does not exceed them, and a temperature just below the maximum acceptable temperature.

The first and second parameters of the fluid may be measured or calculated parameters, for example at a given point of the fluid circuit or in the fluid tank.

At least one of the first parameter and the second parameter of the fluid may be a fluid temperature. Thus, in embodiments where the heat exchanger is a cooler:

-if the fluid temperature is higher than a predetermined value, the fluid has to pass through the heat exchanger, and, if it is determined that some fluid has to be directed to the fluid tank before entering the apparatus, the fluid is conveyed through the first recirculation line, i.e. downstream the heat exchanger;

if the fluid temperature is below a predetermined value, the fluid does not need to pass through the heat exchanger, and if it is determined that some fluid has to be directed to the fluid tank before entering the apparatus, the fluid is conveyed through the second recirculation line, i.e. upstream of the heat exchanger. Thus, the fluid returning to the fluid tank does not flow through the heat exchanger (it need not flow through the heat exchanger in view of the temperature of the fluid), so the pressure drop is reduced.

In an embodiment, at least one of the first and second parameters of the fluid is the temperature of the fluid in the supply line, preferably downstream of the outlet of the bypass line (i.e. at the inlet of the apparatus). Alternatively, the parameter may be a fluid temperature at another location of the fluid circuit, for example: at the outlet of the heat exchanger, upstream of the bypass line outlet, or upstream of the bypass line inlet.

The first parameter and the second parameter may be the same.

With respect to the first control device and the second control device, they may be configured to synchronize displacements of the first valve and the second valve. The first control means and the second control device may be one and the same.

By "synchronized" is meant that the actuation of the first valve and the actuation of the second valve are carried out so as to achieve a corresponding and appropriate full or partial opening/closing of the main line and the bypass line on the one hand and/or of the first recirculation line and the second recirculation line on the other hand, to control the respective fluid flows in the fluid circuit and to provide an efficient pressure and temperature regulation.

In one embodiment, the first and second valves comprise one and the same body forming the movable member of one and the same valve device.

In other words, according to this embodiment, the invention relates to a fluid circuit comprising:

-a supply line for conveying fluid from a pump connected to a fluid tank to at least one device, a portion of the supply line being divided into a main line comprising a heat exchanger and a bypass line for bypassing the heat exchanger, the main line and the bypass line being arranged in parallel and each having an inlet and an outlet;

-a first recirculation line branching off from the supply line downstream of the bypass line outlet for conveying fluid from the supply line towards the fluid tank;

-a second recirculation line branching off from the supply line upstream of the bypass line inlet for conveying fluid from the supply line towards the fluid tank;

-valve means comprising a movable member whose displacement is controlled by the control means in dependence on a parameter of the fluid, such as the fluid temperature, the movable member forming both a first valve for controlling the respective fluid flow in the main line and in the bypass line and a second valve for controlling the respective fluid flow in the first recirculation line and in the second recirculation line;

-a pressure regulating valve for controlling the fluid flow directed back to the fluid tank through the first recirculation line and/or the second recirculation line.

In particular, the invention may provide a single thermostatic valve, the actuation of which allows to control the fluid flow through the heat exchanger and through the pressure regulating circuit. By actuation of a single thermostatic valve, the invention makes it possible to control the fluid flow both through the heat exchanger and through the pressure regulating circuit.

Alternatively, the first and second valves may be separate components, so long as their respective movements are synchronized to allow for adequate regulation of both fluid pressure and temperature.

The control means may comprise a wax element sensitive to the temperature of the fluid, or electrical components (solenoid valves, motors, etc.) controlled by the control unit.

The first valve may be arranged upstream of the heat exchanger or downstream of the heat exchanger.

The first valve may be a three-way valve. Typically, the three-way valve may be arranged at an inlet of the bypass line, and may include: an inlet communicating with a portion of the supply line connected to the pump outlet, a first outlet opening to the heat exchanger, and a second outlet opening to the bypass line.

Alternatively, the first valve may be a two-way valve arranged in the bypass line. With this arrangement, the first valve does not directly control the fluid flow in the main line. Instead, it controls the fluid flow in the bypass line and thus the fluid flow through the heat exchanger in the main line.

The pressure regulating valve may comprise a first passage for the first recirculation line and a second passage for the second recirculation line, the pressure regulating valve being movable between a closed position in which both the first passage and the second passage are closed and an open position in which both the first passage and the second passage are open.

The displacement of the pressure regulating valve may be controlled in dependence of the fluid pressure in the fluid circuit, e.g. in the supply line, preferably downstream of the outlet of the bypass line (i.e. at the inlet of the device).

According to a second aspect, the invention relates to a fluid system comprising a fluid circuit as described above, and further comprising a fluid tank and a constant displacement pump arranged between the fluid tank and the supply line inlet.

According to a third aspect, the invention relates to a vehicle, in particular an industrial vehicle, such as a truck, bus or construction vehicle, comprising a fluid system and an engine as described above, wherein the fluid is oil, and at least one device, such as a vehicle device lubricated by the fluid, a vehicle device cooled by the fluid or a vehicle device moved by the fluid. The heat exchanger may typically be an oil cooler.

According to a fourth aspect, the invention relates to a method for controlling a flow of fluid supplied from a fluid tank to at least one device by means of a constant displacement pump and a supply line, a portion of which is divided into a main line comprising a heat exchanger and a bypass line for bypassing the heat exchanger, the main line and the bypass line being arranged in parallel and both having an inlet and an outlet, wherein the method comprises:

-monitoring a first parameter of the fluid and controlling a respective fluid flow in the main line and in the bypass line in accordance with the first parameter;

-monitoring a second parameter of the fluid;

-controlling a fluid return flow from the supply line directed back to the fluid tank as a function of the fluid pressure, and controlling respective fluid flows delivered back from (i) a region of the supply line downstream of the bypass line outlet and (ii) a region upstream of the bypass line inlet as a function of the second parameter.

In an embodiment, at least one of the first and second parameters of the fluid is a fluid temperature, preferably a fluid temperature in the supply line or in a fluid tank. Advantageously, the first parameter and the second parameter may be one and the same.

The following steps may be performed in synchronization: a step of controlling respective fluid flows in a main line and a bypass line in accordance with the first parameter; and a step of controlling, as a function of said second parameter, the respective fluid flows delivered back from the supply line (i) in a region downstream of the bypass line outlet and (ii) in a region upstream of the bypass line inlet. This may be achieved, for example, by one and the same movable member, which is controlled by a single control device according to one and the same parameter.

In case the second parameter is a fluid temperature (preferably a fluid temperature in the supply line or in a fluid tank) and the heat exchanger is a cooler, the method may mean, when it is determined that a part of the fluid has to be transported back to the fluid tank due to the fluid pressure:

-when the fluid temperature is below a first predetermined threshold, the fluid directed back to the tank is only delivered from a region of the supply line upstream of the bypass line inlet;

and/or, when the fluid temperature is higher than a second predetermined threshold, the fluid directed back to the tank is only delivered from a region of the supply line downstream of the bypass line outlet.

The second threshold is preferably higher than the first threshold.

When the fluid temperature is between the first threshold and the second threshold, a portion of the fluid directed back to the tank may be delivered from a region of the supply line downstream of the bypass line outlet and a region upstream of the bypass line inlet.

Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.

Drawings

With reference to the accompanying drawings, the following is a more detailed description of embodiments of the invention cited as examples.

In these figures:

FIG. 1 is a schematic view of a fluid system according to an embodiment of the present invention;

FIG. 2a shows the fluid system in an operating state when no fluid is directed back to the fluid tank; FIG. 2b shows the fluid system under the same operating conditions when some fluid is directed back to the tank;

FIGS. 3a and 3b, FIGS. 4a and 4b, FIGS. 5a and 5b, FIGS. 6a and 6b are similar to FIGS. 2a and 2b, respectively, under various other operating conditions;

FIG. 7 is a schematic view of a fluid system according to another embodiment of the present invention;

FIG. 8 is a schematic view of a fluid system according to yet another embodiment of the present invention.

Detailed Description

Fig. 1 schematically shows a fluid system 1 according to an embodiment of the invention, the fluid system 1 comprising a fluid tank 2, a fluid circuit 3 and a pump 4, preferably a fixed displacement pump.

The fluid circuit 3 comprises a supply line 5 having an inlet 6 and an outlet 7, the pump 4 being arranged between the fluid tank 2 and the supply line inlet 6. The supply line 5 allows to convey fluid from the fluid tank 2 to at least one device 8.

The fluid system 1 may be part of a vehicle (not shown), in particular an industrial vehicle, such as a truck, bus or construction vehicle. In this application, the fluid may be oil and may be used to lubricate, cool or move a device 8 of the vehicle.

A part of the supply line 5 is divided into two lines arranged in parallel, namely:

a main line 10, said main line 10 having an inlet 11 and an outlet 12, said main line 10 comprising a heat exchanger 13, for example constituted by an oil cooler; and

a bypass line 15, said bypass line 15 having an inlet 16 and an outlet 17, said bypass line 15 allowing to bypass the heat exchanger 13.

The fluid circuit 3 further comprises a first recirculation line 21 branching off from the supply line 5 downstream of the bypass line outlet 17, and a second recirculation line 22 branching off from the supply line 5 upstream of the bypass line inlet 16. Both recirculation lines 21, 22 allow, when appropriate, a portion of the fluid from the supply line 5 to be directed back to the fluid tank 2 before it enters the apparatus 8.

In practice, the fluid circuit 3 comprises a pressure regulating valve 23 for regulating the fluid pressure in the fluid circuit 3, i.e. for allowing at least a part of the fluid to return to the fluid tank 2. The pressure regulating valve 23 is controlled in dependence on the fluid pressure P in a point of the fluid circuit 3, for example a point in the supply line 5 downstream of the bypass line outlet 17. The pressure regulating valve 23 receives fluid pressure P information through a pipe 24.

The pressure regulating valve 23 comprises a first passage 25 for the first recirculation line 21 and a second passage 26 for the second recirculation line 22. The pressure regulating valve 23 is movable between a closed position, in which both the first passage 25 and the second passage 26 are closed (see for example fig. 1 and 2a), and an open position, in which both the first passage 25 and the second passage 26 are open (see for example fig. 2 b).

According to a general definition of the invention, the fluid circuit 3 further comprises:

a first valve 31 for controlling the respective fluid flows in the main line 10 and in the bypass line 15, and first control means for controlling the first valve in dependence on a first parameter of the fluid;

a second valve 32 for controlling the respective fluid flows in the first recirculation line 21 and in the second recirculation line 22, and second control means for controlling the second valve 32 in dependence on a second parameter of the fluid.

In the non-limiting embodiment shown, a valve device 30 is provided, the valve device 30 comprising a movable member, a first part of which forms a first valve 31 and a second part of which forms a second valve 32. In other words, the first valve 31 and the second valve 32 comprise one and the same body forming the movable member of one and the same valve device 30. The valve means 30 are controlled by one and the same control means 33 (as first and second control means), said control means 33 being actuated according to one and the same parameter (as first and second parameter).

The parameter may be the fluid temperature T. In the embodiment shown, the fluid temperature T is measured at a point in the supply line 5 downstream of the bypass line outlet 17. However, the fluid temperature T may be measured in another region of the supply line 5, in the fluid tank 2, etc., as long as it allows effective control of the valve arrangement 30.

The control means 33 may be of any suitable type. It may comprise a wax element or an electrical component.

With the above embodiment, the first valve 31 and the second valve 32 are moved simultaneously. In other words, the valve means 30 are used both for opening or closing the bypass line 15 and for switching between the following two recirculations: i.e. from the region of the supply line 5 upstream of the heat exchanger 13; and from the region of the supply line 5 downstream of the heat exchanger 13.

According to the embodiment shown in fig. 1 to 6b, the first valve 31 of the valve arrangement 30 may be, for example, a three-way valve arranged upstream of the heat exchanger 13, while the second valve 32 may be, for example, a four-way valve arranged in both the first recirculation line 21 and the second recirculation line 22.

The operation of the fluid system 1 will now be described with reference to fig. 2a to 6 b. The fluid system is shown when the measured fluid temperature is T-T1 (fig. 2a and 2b) and gradually increases to T2 (fig. 3a and 3b), T3 (fig. 4a and 4b), T4 (fig. 5a and 5b), and T5 (fig. 6a and 6 b). In the figure with the letter "a", no fluid recirculation is provided, whereas in the figure with the letter "b", the pressure regulation is active, meaning that a part of the fluid is led back to the fluid tank 2 before it enters the apparatus 8. In practice, the pressure regulating valve 23 opens when the pressure P in the pipe 24 is higher than a pressure regulating valve set value, which depends on the load of a biasing member 28 connected to the pressure regulating valve 23. As explained below, as the fluid temperature T increases, the valve arrangement 30 moves further in the same direction, thereby causing a change in fluid flow.

Fig. 2a and 2b show the fluid system 1 when the fluid temperature T is T1, T1 being rather low. In practice, this occurs from the lowest acceptable temperature of the system (about-40 ℃) to T2, T2 may be about 115 ℃ for example. It must be noted that these values are given as examples only and should not be considered as limiting. Furthermore, if the temperature is measured at another location of the fluid system, these values may vary to some extent.

When T-T1, there is no need to cool the fluid being provided to the device 8. Thus, the valve arrangement 30 is positioned such that no fluid flows through the heat exchanger 13 and all fluid flows through the bypass line 15.

In this position, the valve arrangement 30 opens the second recirculation line 22 and closes the first recirculation line 21. Thus, when pressure regulation is required (fig. 2b), the pressure regulating valve 23 is at least partially opened, so that some fluid is redirected to the fluid tank 2. In this case, the redirected fluid is only conveyed from the supply line 5 through the second recirculation line 22 (i.e. from the region of the supply line 5 upstream of the bypass line inlet 16 (i.e. upstream of the heat exchanger 13)). This does not affect the operation of the system as the fluid is cold enough to not require it to pass through the heat exchanger 13. Conversely, redirecting the fluid upstream from the heat exchanger prevents the fluid from unnecessarily passing through the heat exchanger, thus significantly reducing pressure losses.

When T reaches T2> T1 (fig. 3a and 3b), the fluid requires some cooling. Thus, the valve means 30, actuated by the control means 33, start to move to partially open the passage of the supply line 5 towards the main line 10 and the heat exchanger 13 through the first valve 31.

The fluid circuit 3 and the valve arrangement 30 are configured such that such a movement of the valve arrangement 30 does not cause the second valve 32 to completely close the second recirculation line 22 nor open the first recirculation line 21. Thus, when pressure regulation is activated (fig. 3b), the fluid returning to the fluid tank 2 is only conveyed by the second recirculation line 22.

When T reaches T3> T2 (fig. 4a and 4b), the fluid temperature is so high that all fluid provided to the device 8 must pass through the heat exchanger 13. For example, T3 may be about 117 ℃. The control device 33 then moves the valve device 30 further, so that the first valve 31 completely closes the passage to the bypass line 15.

Again, the fluid circuit 3 and the valve arrangement 30 are configured such that such a movement of the valve arrangement 30 does not result in the second valve 32 completely closing the second recirculation line 22 nor opening the first recirculation line 21. Thus, when pressure regulation is activated (fig. 4b), the fluid returning to the fluid tank 2 is only conveyed by the second recirculation line 22.

When T reaches T4> T3 (fig. 5a and 5b), the valve means 30 is moved further by the control means 33. For example, T4 may be about 118 ℃.

On the one hand, such a movement of the valve arrangement 30 does not change the fluid flow provided to the device 8 through the supply line 5, since all fluid still passes through the heat exchanger 13 in order to be cooled.

On the other hand, this causes the second valve 32 to partially close the second recirculation line 22 and partially open the first recirculation line 21, as shown in fig. 5 b. In fact, since the fluid temperature is quite high, recirculating the fluid only through the second recirculation line 22 will result in less fluid flowing through the heat exchanger 13 and thus insufficient cooling of the fluid. However, the fluid temperature is still low enough to allow some of the fluid returning to the fluid tank 2 to be conveyed by the second recirculation line 22, since another part of the fluid returning to the fluid tank 2 is conveyed by the first recirculation line 21, i.e. already cooled in the heat exchanger 13.

Finally, when T reaches T5> T4 (fig. 6a and 6b), the fluid temperature approaches the highest acceptable value. For example, T5 can be between about 119 ℃ and 120 ℃. All of the fluid flow provided to the apparatus 8 must pass through the heat exchanger 13. The valve arrangement 30 is configured such that further movement thereof from the previous position (shown in fig. 5a and 5b) has opened the passage towards the heat exchanger 13.

The aforementioned movement of the valve arrangement 30 further causes the second valve 32 to completely close the second recirculation line 22 and open the first recirculation line 21. Then, when pressure regulation is activated (fig. 6b), the redirected fluid is transported from the supply line 5 to the fluid tank 2 only through the first recirculation line 21, i.e. from the region of the supply line 5 downstream of the bypass line outlet 17, i.e. downstream of the heat exchanger 13. In fact, under these operating conditions, the second recirculation line 22 cannot be used, since it cannot ensure sufficient cooling of the fluid and may eventually damage the plant 8. Here, the reduction of the pressure loss is a secondary objective that is not taken into account, since the primary objective is the cooling of the fluid.

Turning now to fig. 7, in another embodiment, the first valve 31 of the valve arrangement 30 may be a three-way valve, for example, arranged downstream of the heat exchanger 13, while the second valve 32 may be a four-way valve, for example, arranged in both the first recirculation line 21 and the second recirculation line 22.

In a further embodiment shown in fig. 8, the first valve 31 may be a two-way valve arranged in the bypass line 15. More specifically, the two-way valve comprises an inlet communicating with the portion of the supply line 5 connected to the pump outlet and an outlet opening towards the bypass line 15. By this embodiment, the first valve 31 controls the fluid flow in the bypass line 15 and thus indirectly in the main line 10.

In an alternative embodiment not shown, the two-way valve of fig. 8 is arranged downstream of the heat exchanger 13.

It is to be understood that the invention is not limited to the embodiments described above and shown in the drawings; rather, one of ordinary skill in the art appreciates that various modifications and changes can be made within the scope of the claims set forth below.