Arrangement for cooling a motor vehicle braking system

Abstract

Title: Arrangement for cooling a motor vehicle braking device The invention relates to an arrangement for cooling a motor vehicle braking device (4) (1), the arrangement (2) comprising a motor-fan unit (8) for cooling a functional element of a powertrain, in particular of a motor and / or battery of a motor vehicle (1), the motor-fan unit (8) having a nozzle configured to hold a fan (7) of the motor-fan unit (8), the nozzle having at least one pivoting flap (10) intended to pivot about an axis so as to allow an airflow (F) to pass beyond a threshold of force exerted on the pivoting flap, the arrangement being characterized in that it further comprises at least one duct (12) configured to direct an airflow (F) towards the braking device (4) to cool said braking device (4),and characterized in that the inlet (14) of said conduit (12) is disposed downstream of the nozzle (8) of the motor-fan assembly (8). Figure for the abbreviation: Fig. 1,

Description

Title of the invention: Arrangement for cooling a motor vehicle braking device

[0001] The present invention relates to an arrangement for cooling a braking device such as a brake disc of a motor vehicle. The present invention also relates to a motor vehicle equipped with such an arrangement. The present invention also relates to a method for cooling a braking device.

[0002] In an automotive market subject to increasingly strict emission standards and an increasingly environmentally conscious customer, manufacturers are turning to low-emission vehicles such as electric vehicles.

[0003] One of the main features expected by customers of this type of vehicle is range. This range is primarily ensured by high-capacity batteries. However, increasing battery size alone is not enough to meet customer needs because they represent a significant weight, cost, and bulk. Aerodynamic drag is also a key factor in optimizing range.

[0004] To optimize vehicle drag, a known solution is to minimize the porosity of the rims. This solution is often implemented for electric vehicles. Similarly, to avoid an increase in drag, it is often preferred to omit the brake air intake, which is designed to bring air to the brakes for cooling. However, the absence of an air intake means that less air can pass through the brakes and the rim; therefore, brake cooling is less efficient.

[0005] Brake temperature is an important parameter during driving, both for track performance and for mountain descents, but also for a vehicle at rest after use. Indeed, during a mountain descent, brake temperature can potentially rise to over 900°C. If the driver stops the vehicle without waiting for the brake temperature to drop, the discs will still be very hot when the vehicle is stationary, which could lead to significant safety and durability problems.

[0006] Indeed, hot discs are likely to transmit their heat to other parts by conduction and radiation, as well as to the air by convection. Furthermore, some of the heat will also be transferred to the brake fluid, which may exceed its melting point. This could result in damage to surrounding parts and a significant, or even total, loss of braking capacity if the The driver restarts the vehicle in its current state. It is therefore essential to find solutions to optimize brake cooling while driving.

[0007] The objective of the present invention is therefore to limit their temperature rise, but also to prevent the braking system from becoming too hot when drivers stop, given the risks associated with this practice. Similarly, it will be important that the impact on other vehicle performance, particularly aerodynamic drag, be as low as possible. Summary of the invention

[0008] The invention therefore relates to an arrangement for cooling a motor vehicle braking device, the arrangement comprising a motor-fan unit for cooling a functional element of a powertrain, in particular of a motor vehicle engine and / or battery, the motor-fan unit having a nozzle configured to hold a fan of the motor-fan unit, the nozzle having at least one pivoting flap intended to pivot about an axis so as to allow an airflow to pass beyond a threshold of force exerted on the pivoting flap, the arrangement being characterized in that it further comprises at least one duct configured to direct an airflow towards the braking device to cool said braking device, and characterized in that the inlet of said duct is disposed downstream of the nozzle of the motor-fan unit.

[0009] According to a particular embodiment, an outlet surface of the conduit is intended to be arranged near a brake disc bowl between a pivot and a caliper of the motor vehicle.

[0010] According to a particular embodiment, an outlet of the duct is oriented in a direction perpendicular to the braking device to be cooled, so that the airflow intended to circulate in the duct is sent to the braking device in said perpendicular direction.

[0011] According to a particular embodiment, the arrangement further comprises a scoop disposed with regard to the outlet of the duct, the scoop being configured to direct an airflow intended to exit the outlet of the duct towards said braking device in order to cool it.

[0012] According to a particular embodiment, the conduit comprises on the one hand a rigid part configured to be fixed on the nozzle and on the other hand a flexible part intended to face a wheel of a motor vehicle, the flexible part being configured to move with the wheel according to the movements of the latter.

[0013] According to a particular embodiment, the flexible part of the conduit and the rigid part of the conduit are linked together in a detachable manner.

[0014] According to a particular embodiment, an outlet surface of the conduit presents dimensions smaller than an inlet surface of said conduit.

[0015] The invention also relates to a motor vehicle comprising an arrangement for cooling a braking device as described above.

[0016] The invention also relates to a method for cooling a braking device when the vehicle is in motion or stationary, characterized in that the cooling method comprises the following steps: - a first step of measuring or estimating the temperature of at least one braking device; - a second step of comparing the measured or estimated temperature to a predefined threshold; - if the measured temperature is above the predefined threshold, a third step of activation of the fan of the motor-fan group of the arrangement according to one of the preceding claims, and repetition of the first step and the second step at regular time intervals.

[0017] According to one embodiment of the method for cooling a braking device, a computer is kept awake when the vehicle is stationary to monitor the evolution of the temperature of the braking device and the fan of the motor-fan group of the arrangement is deactivated and / or the controlled flaps closed as long as the measured temperature is below a predefined threshold. Presentation of figures

[0018] These objects, features and advantages of the present invention will be described in detail in the following description of various particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0019] Fig. 1 is a schematic representation of a cross-sectional view of a front portion of a motor vehicle equipped with an arrangement according to a first embodiment of the invention.

[0020] Fig. 2 is another schematic representation of the arrangement of Fig. 1 mounted within a vehicle.

[0021] The [Fig.3] is a schematic representation of another embodiment of the arrangement of the [Fig.1].

[0022] Fig. 4 is a view similar to Fig. 1 and schematically represents another embodiment of the arrangement.

[0023] Fig. 5 is a view similar to those of Figures 1 and 4 and schematically represents another embodiment of the arrangement. Detailed description

[0024] The air intakes of a vehicle 1 are generally located at the front of said vehicle 1, for example at the level of the grille. These air intakes allow to supply the various air networks of the engine compartment, they serve in particular to supply air to at least one cooling module which includes heat exchangers constituting part of an engine cooling circuit and / or an air conditioning circuit.

[0025] In the context of this patent application, the air inlets also supply an arrangement 2 for cooling a braking device 4 of a motor vehicle 1. Such an arrangement 2 is shown schematically in [Fig.1] and in [Fig.2].

[0026] The arrangement 2 includes at least one heat exchanger 6 through which the cooling air is in heat exchange with a fluid circulating in the engine cooling circuit and / or in the air conditioning circuit of the motor vehicle 1.

[0027] The arrangement includes a motor-fan assembly 8 for cooling a functional element of a powertrain, in particular an engine and / or a battery of a motor vehicle. The motor-fan assembly 8 conventionally includes a nozzle equipped with at least one pivoting flap 10 designed to pivot about an axis so as to allow an airflow F to pass beyond a threshold of force exerted on the pivoting flap 10. The nozzle also plays a supporting role: it helps to hold the fan 7 of the motor-fan assembly 8 within the vehicle 1.

[0028] The force exerted on the pivoting flap 10 is exerted directly by the air passing through the air inlets. By pivoting around an axis of rotation, the flap 10 creates a passage through which an airflow F is intended to circulate. This type of flap 10 is commonly referred to as a "passive" flap in the sense that its pivoting is not controllable, since the pivoting of this type of flap 10 depends on the threshold of force exerted on the flap 10, that is, on the air pressure exerted on the surface of the pivoting flap 10. Generally, a nozzle of a motor-fan unit 8 is equipped with a multitude of flaps 10.

[0029] Thus, when the air pressure exerted on the surface of said flaps 10 is sufficient, particularly when the motor vehicle 1 is traveling at a given speed (for example, greater than or equal to 70 km / h), the flaps 10 pivot around their axis of rotation. The degree of opening of the pivoting flaps 10 also depends on the air pressure exerted on the surface of said flaps 10.

[0030] Opening these pivoting flaps 10 increases the airflow through the arrangement 2 for cooling when the vehicle 1 is traveling at high speed. At low speed, the air pressure is generally not high enough to open these flaps, which therefore remain closed.

[0031] The arrangement 2 further includes at least one duct 12 configured to direct the airflow F towards a braking device 4 of the vehicle 1 to cool said device braking 4.

[0032] This duct 12 has an air inlet 14 located downstream of the nozzle of the motor-fan unit 8. The location of the air inlet 14 of the duct 12 downstream of the nozzle allows the use of the airflows F already circulating through said nozzle. With such an arrangement 2, it is thus possible to do without an additional air inlet at the front of the vehicle 1, thereby limiting, or even reducing, aerodynamic drag. In the embodiment illustrated in [Fig. 2], the air inlet 14 of the duct 12 is more particularly located downstream of at least one pivoting flap 10 of the nozzle of the motor-fan unit 8, that is to say, behind the pivoting flap of the nozzle, in the direction of the airflow F.

[0033] Advantageously, arrangement 2 allows the airflow F to pass through the open flap 10 of the nozzle 8 directly into the duct 12, which directs said airflow F towards the braking device 4 to be cooled, thus increasing cooling efficiency while limiting the number of parts required. This has the advantage of making arrangement 2 more compact, thereby saving space. Furthermore, the air exiting the duct 12 can be directed directly to where its use is relevant, for example, to a caliper 9 or the brake pads of the braking device 4.

[0034] The arrangement 2 may have various optional features that further increase cooling efficiency. Thus, according to a preferred embodiment, an outlet surface 16 of the duct 12 may have dimensions smaller than an inlet surface 14 of the same duct 12. This increases the air velocity at the outlet 16 of the duct 12 in order to optimize the cooling of the braking device 4.

[0035] According to a non-limiting example, the inlet surface 14 of the conduit 12 can be between 1000 and 2500 mm2 while the outlet surface 16 of the conduit 12 can be between 800 and 2000 mm2.

[0036] Furthermore, according to a preferred embodiment, the duct 12 can be arranged in the configuration 2 such that the outlet surface 16 of the duct 12 is located near a brake disc hub between a pivot and the caliper 9 of the motor vehicle 1, as illustrated in [Fig. 4]. This location of the outlet 16 of the duct 12 allows the air to be efficiently directed towards the braking device 4 to be cooled, thus optimizing its cooling.

[0037] By way of non-limiting example, the braking device 4 may include brake discs. These brake discs may also be equipped with channels through which the airflow from the outlet 16 of the duct 12 is intended to circulate in order to optimize the cooling of the brake discs. By placing the outlet surface 16 of the duct 12 close to the hub of the brake disc, Between the pivot and the caliper 9, the airflow from the outlet 16 of the duct 12 is precisely and efficiently directed to the braking device 4 to be cooled. Furthermore, the air exiting the duct 14 can be directed directly to where it is most needed, for example, to the caliper 9 or the brake pads of the braking device 4.

[0038] Furthermore, the outlet 16 of the duct 12 can be oriented in a direction perpendicular to the braking device 4 to be cooled, so that the airflow F intended to circulate in the duct 12 is directed onto the braking device 4 in said perpendicular direction, thus optimizing its cooling. Such a configuration is illustrated in particular in [Fig. 3], in which a terminal portion of the duct 12 is bent, so that the outlet 16 of said duct 12 is oriented perpendicular to the surface of the brake disc of the braking device 4 visible in this [Fig. 3].

[0039] According to an advantageous embodiment which is also illustrated in this same [Fig.3], the duct 12 may comprise on the one hand a rigid part 13 configured to be fixed on the nozzle of the motor-fan unit 8 and on the other hand a flexible part 15. The flexible part 15 is more particularly configured to move with the wheel 17 according to the movements of the latter, so that the airflow F exiting the duct 12 is always directed towards the braking device 4, regardless of the position of the wheel 17 of the motor vehicle 1. The cooling of the braking device 4 is thus optimized under all circumstances.

[0040] In the example illustrated in [Fig. 3], the flexible part 15 of the duct 12 is bent several times, thus adapting to the surrounding parts in the arrangement 2. It will also be noted that in the case of the embodiment illustrated in [Fig. 3], the flexible part 15 of the duct 12 is longer than the rigid part 13 of the duct 12. The rigid part 13 of the duct 12 is, for example, screwed or clipped onto the nozzle of the motor-fan assembly 8.

[0041] According to a variant of this embodiment, the flexible part 15 of the conduit 12 and the rigid part 13 of the conduit 12 are connected to each other in a detachable manner. It is thus possible to separate the flexible part 15 of the conduit 12 from the rigid part 13 of the conduit 12, which notably allows only the flexible part 15 of the conduit 12 to be replaced, as it is a priori more likely to wear out than the rigid part 13 of the conduit 12.

[0042] According to another embodiment, as illustrated in [Fig. 5], the arrangement 2 may include a scoop 18 configured to direct the airflow F intended to circulate in the duct 12 towards the braking device 4 in order to cool it. Such a scoop 18 may, for example, be attached to a suspension arm of the motor vehicle 1. Generally, the scoop 18 may be mounted on the wheel assembly 17 of the motor vehicle 1.

[0043] Finally, the duct 12 and the scoop 18 can be coupled. This allows the duct 12 to remain a single rigid part. The scoop 18 is then placed in line with the duct 12 in order to guide the airflow F as close as possible to the braking device 4.

[0044] In general, the arrangement 2 for cooling the braking device 4 does not require a separate cooling system, which makes it possible to forgo separate air guidance channels to the wheel brakes 17. Such an arrangement 2 can also avoid the provision of additional air inlets at the front of the vehicle 1 which could have a negative influence on the drag of the vehicle 1 when it is used for movement.

[0045] The invention is not limited to the front wheel arches 17 of motor vehicles 1, and can of course be applied in a similar way to the rear wheel arches, preferably in combination with an engine unit located at the rear of the motor vehicle 1. According to one variant, the aforementioned arrangement could also be applied to vehicle types with air intakes located in the center of the vehicle.

[0046] Such an arrangement 2 for cooling a braking device 4 of a motor vehicle 1 can in particular be used for implementing a method of cooling such a braking device 4 when the vehicle 1 is stationary or at low speed (for example less than 70 km / h), in particular after having been used for a journey during which the braking device(s) 4 have been used.

[0047] This method of cooling a braking device 4 is carried out when the vehicle is in motion or stationary. Furthermore, this cooling method takes into account the thermal state of the braking device 4 when the vehicle 1 is stationary, but in a state where the electronic control components of the functional elements, such as those controlling the operation of the motor-fan assembly 8, are awake.

[0048] This method includes a first step of measuring or estimating the temperature of at least one braking device 4, then a second step of comparing the measured or estimated temperature to a predefined threshold; and; if the measured or estimated temperature is greater than the predefined threshold, a step of activating the fan 7 of the motor-fan group 8 of the arrangement 2 as described previously.

[0049] The efficiency of this process can be enhanced by applying scoop 18 which will allow the air from the fans to be directed more efficiently towards the braking system.

[0050] In the case where the vehicle 1 equipped with a cooling arrangement 2 as described above is also equipped with at least one controlled flap on a front face of the vehicle 1, for example in front of at least one heat exchanger 6, and / or at the level of a grille, the cooling process may be provided for opening the or the controlled flaps of the front of the vehicle 1 in parallel with the activation of the fan 7 of the motor-fan group 8.

[0051] The activation step of the fan 7 of the motor-fan assembly 8 of the arrangement 2 as described above can also be forcibly triggered by a user of the motor vehicle, such as the driver. In this case, the driver can voluntarily activate the cooling of the braking system when stopping the vehicle in preparation for a specific use, such as track use. This manual activation can be carried out via an interface or a dedicated button, for example.

[0052] By temperature of the braking device 4, we mean the temperature of at least one sensitive element of the braking device 4, such as a brake disc. During the first step of measuring the temperature of at least one braking device 4, this temperature measurement can therefore be carried out at the brake disc or via the brake fluid, for example. This measurement can be performed using a physical sensor or based on a temperature estimator constructed according to other parameters. Other strategic locations for measuring the temperature of at least one braking device 4 can be considered.

[0053] By way of example, the predefined threshold for the second step of the process, where the measured or estimated temperature is compared to said threshold, is set for example at 300°C. Other threshold values ​​may be considered.

[0054] In this cooling method, several activation levels can be considered for the fan motor assembly 8 depending on the evolution of the measured or estimated temperature of the braking device 4. In particular, five different activation levels can be defined. Thus, if the temperature of the braking device 4 continues to rise despite a first-level activation of the fan motor assembly 8, a higher-level activation (for example, a second-level activation when the temperature has exceeded a threshold of 400°C) can occur. As long as the temperature is rising, a higher activation level than the previous level can be considered, up to the maximum activation level. Conversely, when the temperature falls, a reduction in the activation level of the fan motor assembly 8 can be carried out until the temperature drops below the initial predefined threshold, for example, 300°C.In this cooling process, the fan 7 of the motor-fan group 8 of arrangement 2 is deactivated when the measured temperature is below the predefined threshold.

[0055] The value of the predefined threshold may depend on the type of vehicle 1 and / or the use made of it before the start of the cooling process of the braking device 4 of said vehicle 1.

[0056] Depending on the result obtained from the comparison of the measured or estimated temperature Relative to the predefined threshold, the fan 7 of the motor-fan assembly 8 of arrangement 2 for cooling a braking device 4 is activated, or even controlled to a higher or lower activation level. Similarly, the controlled flaps will be opened if they were previously closed. To achieve this, a control unit can be kept awake when the vehicle is stationary to monitor the temperature evolution of the braking device 4.

[0057] The first step of measuring the temperature of at least one braking device 4 and the second step of comparing said measured value with the predefined threshold are repeated at regular time intervals, for example, every ten seconds. Other time intervals may be considered, for example, every fifteen seconds, or every thirty seconds, or every minute. It may also be envisaged to use different time intervals during the same process, for example, repeating the first and second steps every ten seconds for a given period, then every thirty seconds for another period during the same implementation of the braking device cooling process.

Claims

Claims

1. Arrangement (2) for cooling a braking device (4) of a motor vehicle (1), the arrangement (2) comprising a motor-fan unit (8) for cooling a functional element of a powertrain, in particular an engine and / or a battery of a motor vehicle (1), the motor-fan unit (8) comprising a nozzle configured to hold a fan (7) of the motor-fan unit (8), the nozzle comprising at least one pivoting flap (10) intended to pivot about an axis so as to allow an air flow (F) to pass beyond a force threshold exerted on the pivoting flap, the arrangement being characterized in that it further comprises at least one duct (12) configured to direct an air flow (F) towards the braking device (4) to cool said braking device (4), and characterized in that the inlet (14) of said duct (12) is arranged downstream of the nozzle (8) of the motor-fan unit (8).

2. Arrangement according to the preceding claim, characterized in that an outlet surface (16) of the conduit (12) is intended to be arranged near a brake disc bowl between a pivot and a caliper (9) of the motor vehicle (1).

3. Arrangement according to one of the preceding claims, characterized in that an outlet (16) of the duct (12) is oriented in a direction perpendicular to the braking device (4) to be cooled, so that the air flow (F) intended to circulate in the duct (12) is sent to the braking device (4) in said perpendicular direction.

4. Arrangement according to one of the preceding claims, characterized in that it further comprises a scoop (18) arranged opposite the outlet of the duct (12), the scoop (18) being configured to direct an air flow (F) intended to exit from the outlet (16) of the duct (12) towards said braking device (4) in order to cool it.

5. Arrangement according to one of the preceding claims, characterized in that the conduit (12) comprises on the one hand a rigid part (13) configured to be fixed on the nozzle (8) and on the other hand a flexible part (15) intended to face a wheel (17) of a motor vehicle (1), the flexible part (15) being configured to move with the wheel (17) according to the movements thereof.

6. Arrangement according to the preceding claim, characterized in that the flexible part (15) of the conduit (12) and the rigid part (13) of the conduit (12) are linked together in a removable manner.

7. Arrangement according to one of the preceding claims, characterized in that an outlet surface (16) of the conduit (12) has smaller dimensions than an inlet surface (14) of said conduit (12).

8. Motor vehicle (1), characterized in that it comprises an arrangement (2) according to one of the preceding claims for cooling a braking device (4).

9. Method for cooling a braking device (4) when the vehicle (1) according to the preceding claim is in a rolling or stationary situation, characterized in that the cooling method comprises the following steps: - a first step of measuring or estimating the temperature of at least one braking device (4); - a second step of comparing the measured or estimated temperature with a predefined threshold; - if the measured temperature is higher than the predefined threshold, a third step of activating the fan (7) of the motor-fan unit (8) of the arrangement (2) according to one of the preceding claims, and repeating the first step and the second step at regular time intervals.

10. Cooling method according to the preceding claim, characterized in that a computer is kept awake when the vehicle is stationary to monitor the evolution of the temperature of the braking device (4) and in that the fan (7) of the motor-fan unit (8) of the arrangement is deactivated and / or the controlled shutters closed as long as the measured temperature is below a predefined threshold.

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