Cooling circuit for a motor vehicle

Abstract

A cooling circuit for a vehicle includes at least one pump (10) and a plurality of branches (12, 14) for circulation of a cooling fluid. At least one branch (12) includes a flow rate limiter (24) with a valve (28), the flow rate limiter including a body (26) in which is mounted a valve (28) mobile between a first position in which it delimits a first fluid passage section (S2) at the outlet of the limiter and a second position in which it delimits a second fluid passage section (S3) in the limiter, the second section being smaller than the first section. The valve is biased into its first position and configured to be moved from the first position to the second position when the fluid flow rate at the inlet of the limiter exceeds a predetermined threshold.

Claims

1. A cooling circuit for a vehicle, said cooling circuit including at least one pump and a plurality of branches for circulation of a cooling fluid, wherein at least one branch includes a flow rate limiter with an inlet, an outlet and a valve, said flow rate limiter including a body in which the valve is mounted for movement between a first position in which the valve delimits a first fluid passage section at the outlet of the limiter and a second position in which the valve delimits a second fluid passage section at the outlet of the limiter, the second fluid passage section being smaller than the first fluid passage section, and the valve being biased into the first position and configured to be moved from the first position to the second position when the fluid flow rate at the inlet of the limiter exceeds a predetermined threshold; wherein the valve comprises an elongate pin slidable in said body, the pin having first and second longitudinal ends, wherein a plurality of longitudinal ribs are arranged on an outer surface of the pin, wherein the longitudinal ribs extend axially beyond the first longitudinal end and the second longitudinal end to form first abutments beyond the first longitudinal end and second abutments beyond the second longitudinal end, wherein the second fluid passage section is defined by engagement of the second abutments with an annular shoulder at the outlet when the valve is in the second position.

2. The cooling circuit according to claim 1, in which the flow rate limiter includes a compression spring that biases the valve into the first position, said compression spring having a compression force chosen as a function of said predetermined threshold.

3. The cooling circuit according to claim 2, in which the compression spring is a coil spring.

4. The cooling circuit according to claim 2, in which the body has a tubular shape and comprises coaxial tubular sections of which a first section has a diameter D1 and defines an internal housing to receive the valve and of which a second section has a diameter D2, less than D1, and defines an internal housing to receive the compression spring.

5. The cooling circuit according to claim 1, in which the valve is independent of said body.

6. The cooling circuit according to claim 1, wherein the pin is cylindrical and the first longitudinal end is formed by an ogive-shaped head.

7. The cooling circuit according to claim 1, wherein the first abutments engage with a further annular shoulder at the inlet when the valve is in the first position.

8. The cooling circuit according to claim 1, in which at least two branches each include a flow rate limiter, said flow rate limiters having different predetermined thresholds for movement of their respective valves.

9. A cooling circuit for a vehicle, said cooling circuit including at least one pump and a plurality of branches for circulation of a cooling fluid, wherein at least one branch includes a flow rate limiter with an inlet, an outlet and a valve, said flow rate limiter including a body in which the valve is mounted for movement between a first position in which the valve delimits a first fluid passage section at the outlet of the limiter and a second position in which the valve delimits a second fluid passage section at the outlet of the limiter, the second fluid passage section being smaller than the first fluid passage section, and the valve being biased into the first position and configured to be moved from the first position to the second position when the fluid flow rate at the inlet of the limiter exceeds a predetermined threshold; wherein the valve comprises an elongate pin slidable in said body, the pin having first and second longitudinal ends, wherein a plurality of abutments extend from the pin beyond the second longitudinal end, wherein the second fluid passage section is defined by engagement of the abutments with an annular shoulder at the outlet when the valve is in the second position, wherein the annular shoulder faces toward the inlet.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Other features and advantages of the invention will become apparent upon reading the following detailed description, to understand which see the appended drawings, in which:

(2) FIG. 1 is a highly diagrammatic view of a cooling circuit of a vehicle,

(3) FIG. 2 is a diagrammatic perspective view of a flow rate limiter according to one embodiment of the invention,

(4) FIG. 3 is a diagrammatic axial sectional view of the flow rate limiter from FIG. 2, its valve being in a first position,

(5) FIG. 4 is a diagrammatic axial sectional view of the flow rate limiter from FIG. 2, its valve being in a second position,

(6) FIG. 5 is a diagrammatic axial sectional view of the body of the flow rate limiter from FIG. 2,

(7) FIG. 6 is a diagrammatic perspective view of the valve of the flow rate limiter from FIG. 2,

(8) FIG. 7 is another diagrammatic perspective view of the valve of the flow rate limiter from FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

(9) As mentioned above, FIG. 1 shows a cooling circuit for a motor vehicle, which is a closed circuit and comprises at least one pump 10 for circulating a cooling fluid, such as water, in a plurality of branches 12, 14.

(10) The branches 12, 14 extend in parallel between the outlet of the pump 10 and a thermostat 20. The thermostat 20 is connected to the inlet of the pump 10 by a direct pipe and by a parallel pipe including a radiator 22.

(11) The branch 12 feeds a device 16 for heating the passenger compartment of the vehicle and the branch 14 feeds an engine block 18 of the vehicle in order to cool it. The circuit may naturally comprise more branches.

(12) The cooling fluid feed flow rate of the engine block 18 is of the order of 120 L/min and depends on the engine speed. At high engine speeds the flow rate increases and at low engine speeds the flow rate decreases. The flow rate of the cooling fluid is therefore a function of the engine speed, which is highly appropriate because the engine block 18 has a cooling requirement proportional to the engine speed.

(13) The branch 12 has for example a cooling fluid flow rate requirement of the order of 40 L/min. This requirement may be considered constant and does not need to be adjusted up and down as a function of the engine speed.

(14) The invention enables this requirement to be addressed by means of a flow rate limiter 24 mounted on the branch 12. The flow rate limiter 24 is of the valve type and comprises a mobile (movable) valve to adjust the fluid passage section and therefore the fluid flow rate at the outlet of the limiter as a function of the flow rate at the inlet of said limiter. The valve is configured to be moved when the fluid flow rate at the inlet of the limiter exceeds a predetermined threshold. Below that threshold the valve is not moved and defines a given passage section at the outlet of the limiter. Starting at and beyond said threshold the valve is moved and adopts a position in which it defines a smaller passage section at the outlet of the limiter, in order for the outlet fluid flow rate to be reduced.

(15) FIGS. 2 to 7 show one embodiment of a flow rate limiter 24.

(16) The limiter 24 essentially comprises a body 26 in which is mounted a mobile valve 28.

(17) In the example shown, the body 26, shown separately in FIG. 5, has a tubular general shape and comprises a plurality of coaxial sections 26a-26d. The body 26 comprises at one longitudinal end a fluid inlet section 26a and at its opposite longitudinal end a fluid outlet section 26d. Between the sections 26a, 26d the body comprises two other sections 26b, 26c having different diameters D1, D2 greater than those of the sections 26a, 26d.

(18) The section 26b with the greater diameter D1 defines a housing to receive the valve 28. The valve 28 is mobile axially in this section between a first position shown in FIG. 3 and a second position shown in FIG. 4.

(19) The section 26c with the smaller diameter D2 defines a housing to receive a member for biasing the valve 28 into its first position. In the example shown said member is a compression spring 30 which is in a relaxed position in FIG. 3 and compressed in FIG. 4. Here the compression spring is a coil spring.

(20) The section 26c is connected to the section 26d by an annular shoulder 32a and to the section 26b by another annular shoulder 32b (FIG. 5). Moreover, the section 26b is connected to the section 26a by another annular shoulder 32c (FIG. 5).

(21) The spring 30 bears at one end on the shoulder 32a and at its opposite end on the valve 28. The valve 28 is mobile in the section 26b and cooperates with the shoulders 32b, 32c to define end of travel positions of the valve in the body 26.

(22) The valve 28 can be seen better in FIGS. 6 and 7 and comprises a pin 34 of cylindrical general shape one longitudinal end of which is conformed as an ogive-shaped head 34a. At its opposite longitudinal end the pin 34 comprises an annular surface 34b on which the spring 30 bears.

(23) The valve 28 further comprises longitudinal ribs 36 to guide it when it slides in the body. Here there are three ribs 36 and they are regularly spaced around the lengthwise axis of the pin 34. They are configured to slide on and therefore to cooperate with the cylindrical internal surface of the section 26b extending between the shoulders 32b, 32c.

(24) The ribs 36 are extended axially beyond the longitudinal ends of the pin 34 to form abutments or abutment surfaces 36a, 36b adapted to cooperate with the shoulders 32b, 32c. The abutments 36a are situated at the same end as the ogive-shaped head 34a and are adapted to bear on the shoulder 32c to define an end of travel position shown in FIG. 3. The abutments 36b are situated at the opposite end of the pin 34 and are adapted to bear on the shoulder 32b to define an end of travel position shown in FIG. 4.

(25) FIG. 3 shows the position of the valve 28 when the spring 30 is in the free or relaxed state. The spring remains in this position as long as the inlet fluid flow rate of the limiter 24 and of the body 26 (arrow F1) is below a predetermined threshold, for example 40 L/min. The abutments 36a bear on the shoulder 32c and define between them three fluid passage sectors between the ogive-shaped head 34a of the pin and the section 26a. These passage sectors define a passage section denoted S1 (which is not shown in the drawings) at the inlet of the limiter 24. At the outlet of the limiter the valve does not significantly obstruct the passage section, which may be denoted S2 (not shown).

(26) FIG. 4 shows the position of the valve 28 when the spring 30 is compressed. The spring adopts this position when the inlet fluid flow rate of the limiter and of the body (arrow F2) is above or at the aforementioned threshold. The fluid bears on the valve 28 and in particular on the ogive-shaped head 34a and moves it in the body 26. It is therefore clear that the compression force of the spring is chosen as a function of the threshold (the compression force of the spring can be selected to provide a desired threshold), said force being 10 N for example in one particular embodiment of the invention. The abutments 36b bear on the shoulder 32b and define between them three fluid passage sectors between the surface 34b of the pin and the section 26c. These passage sectors define a passage section denoted S3 (which is not shown). S3 is less than the passage section S2 at the outlet of the limiter 24 when the valve 28 is in the FIG. 3 position. The limiter 24 therefore enables reduction of the fluid flow rate in the branch 12 to just what is required to feed the devices in that branch.

(27) The cooling circuit may comprise a flow rate limiter 24 on one branch 12 and advantageously comprise a flow rate limiter on a plurality of branches 12, 12′. In the latter case, the flow rate limiters may have different predetermined valve movement thresholds.