Arrangement and method for cooling a motor vehicle braking device

Abstract

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

Description

[0001] ARRANGEMENT AND METHOD FOR COOLING A MOTOR VEHICLE BRAKING DEVICE

[0002] 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.

[0003] In an automotive market subject to increasingly stringent emissions standards and an increasingly environmentally conscious customer, manufacturers are turning to low-emission vehicles such as electric vehicles.

[0004] One of the main features expected by customers of this type of vehicle is range. This range is primarily ensured by large-capacity batteries. However, increasing the size of batteries alone is not enough to meet customer needs because they represent significant weight, cost, and bulk. Aerodynamic drag is also a key factor in optimizing range.

[0005] In order to optimize the vehicle's drag, a known solution is to try to reduce the porosity of the rims as much as possible. This solution is often implemented for electric vehicles. Similarly, in order to avoid an increase in drag, it is often preferred to forgo the presence of a scoop, which has the role of bringing air to the brakes to cool them. However, the absence of a scoop means that there is less air that will be able to pass through the brakes and the rim; the cooling of the brakes is therefore less effective. However, the thermal performance of the brakes is an important parameter when driving, both for circuit performance and for descents of passes, but also for a vehicle stopped after use. Indeed, when descending a pass, the temperature of the brakes can potentially rise to more than 900°C.If the driver stops the vehicle without waiting for the brake temperature to drop, the discs will still be very hot when stopped, which can cause significant safety and durability issues.

[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. In addition, some of the heat will also be transmitted to the brake fluid, which will potentially exceed its melting temperature. This could result in damage to the surrounding parts as well as a significant, or even total, loss of braking capacity if the driver restarts the vehicle as is. 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 being too hot when drivers stop, given the risks associated with this practice. Similarly, it will be important that the impact on the other performance of the vehicle, in particular aerodynamic drag, is as low as possible.

[0008] Summary of the invention

[0009] 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 an engine and / or a motor vehicle battery, the motor-fan unit comprising a nozzle configured to hold a fan of the motor-fan unit, the nozzle comprising at least one pivoting flap intended to pivot about an axis so as to allow a flow of air to pass beyond a force threshold exerted on the pivoting flap, the arrangement being characterized in that it further comprises at least one duct configured to direct a flow of air towards the braking device to cool said braking device, and characterized in that the inlet of said duct is arranged downstream of the nozzle of the motor-fan unit.

[0010] According to a particular embodiment, an outlet surface of the duct is intended to be arranged near a brake disc bowl between a pivot and a caliper of the motor vehicle.

[0011] 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 air flow intended to circulate in the duct is sent to the braking device in said perpendicular direction.

[0012] According to a particular embodiment, the arrangement further comprises a scoop arranged opposite the outlet of the duct, the scoop being configured to direct a flow of air intended to exit the outlet of the duct towards said braking device in order to cool it.

[0013] 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 motor vehicle wheel, the flexible part being configured to move with the wheel according to its movements.

[0014] According to a particular embodiment, the flexible part of the conduit and the rigid part of the conduit are connected to each other in a removable manner. According to a particular embodiment, an outlet surface of the conduit has 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 moving or stationary, characterized in that the cooling method comprises the following steps:

[0017] - a first step of measuring or estimating the temperature of at least one braking device;

[0018] - a second step of comparing the measured or estimated temperature to a predefined threshold;

[0019] - if the measured temperature is higher than the predefined threshold, a third step of activating the fan of the motor-fan unit of the arrangement according to one of the preceding claims, and repeating the first step and the second step at regular time intervals.

[0020] 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 unit of the arrangement is deactivated and / or the controlled shutters closed as long as the measured temperature is below a predefined threshold.

[0021] Presentation of figures

[0022] These objects, characteristics and advantages of the present invention will be explained in detail in the following description of different particular embodiments made without limitation in relation to the attached figures among which: Figure 1 is a schematic representation of a sectional view of a front portion of a motor vehicle equipped with an arrangement according to a first embodiment of the invention.

[0023] Figure 2 is another schematic representation of the arrangement of Figure 1 mounted within a vehicle.

[0024] Figure 3 is a schematic representation of another embodiment of the arrangement of Figure 1.

[0025] Figure 4 is a view similar to Figure 1 and schematically represents another embodiment of the arrangement.

[0026] Figure 5 is a view similar to those of Figures 1 and 4 and schematically represents another embodiment of the arrangement.

[0027] Detailed description

[0028] The air inlets of a vehicle 1 are generally arranged at the front of said vehicle 1, for example at the level of the grille. These air inlets make it possible to supply the various air networks of the engine compartment, they are used in particular to supply air to at least one cooling module which comprises heat exchangers constituting a part of an engine cooling circuit and / or an air conditioning circuit.

[0029] In the context of this patent application, the air inlets also make it possible to supply an arrangement 2 for cooling a braking device 4 of a motor vehicle 1. Such an arrangement 2 is shown schematically in Figure 1 and in Figure 2.

[0030] The arrangement 2 comprises 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. The arrangement comprises a motor-fan unit 8 for cooling a functional element of a powertrain, in particular an engine and / or a motor vehicle battery. The motor-fan unit 8 conventionally comprises a nozzle provided with 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 10. The nozzle also plays a support role: it makes it possible to maintain the fan 7 of the motor-fan unit 8 within the vehicle 1.

[0031] The force exerted on the pivoting flap 10 is exerted directly by the air passing through the air inlets. By pivoting about an axis of rotation, the flap 10 makes it possible to clear a passage through which an air flow 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, because the pivoting of this type of flap 10 depends on the force threshold exerted on the flap 10, that is to say 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.

[0032] Thus, when the air pressure exerted on the surface of said flaps 10 is sufficient, in particular 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 opening rate of the pivoting flaps 10 also depends on the air pressure exerted on the surface of said flaps 10.

[0033] The opening of these pivoting flaps 10 makes it possible to increase the air flow 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 then remain closed. The arrangement 2 further comprises at least one duct 12 configured to direct the air flow F towards a braking device 4 of the vehicle 1 to cool said braking device 4.

[0034] This duct 12 has an air inlet 14 which is arranged 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 makes it possible to use the air flows F which already circulate through said nozzle. With such an arrangement 2, it is thus possible to do without an additional air inlet at the front of the motor vehicle 1, thus making it possible to limit the aerodynamic drag, or even to reduce it. In the embodiment illustrated in FIG. 2, the air inlet 14 of the duct 12 is more particularly arranged downstream of the 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 circulation of the air flow F.

[0035] Advantageously, the arrangement 2 makes it possible to pass the air flow F through the open flap 10 of the nozzle 8 directly into the duct 12 which directs said air flow F towards the braking device 4 to be cooled, thus increasing the cooling efficiency while limiting the number of parts required, which has the advantage of making the arrangement 2 more compact, thus saving space. In addition, the air leaving the duct 12 can be directly directed to where its use will be relevant, for example at a caliper 9 or the brake pads of the braking device 4.

[0036] The arrangement 2 may have various optional features that make it possible to further increase the cooling efficiency. Thus, according to a preferred embodiment, an outlet surface 16 of the duct 12 may have smaller dimensions than an inlet surface 14 of this same duct 12. This makes it possible to increase the air speed at the outlet 16 of the duct 12 in order to optimize the cooling of the braking device 4.

[0037] According to a non-limiting example, the inlet surface 14 of the conduit 12 may be between 1000 and 2500 mm 2 while the outlet surface 16 of the conduit 12 can be between 800 and 2000 mm 2 .

[0038] Furthermore, according to a preferred embodiment, the duct 12 can be arranged in the arrangement 2 such that the outlet surface 16 of the duct 12 is located close to a bowl of the brake disc 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 makes it possible to efficiently direct the air towards the braking device 4 to be cooled, thus optimizing their cooling.

[0039] According to a non-limiting example, the braking device 4 may in particular comprise brake discs. These brake discs may also be equipped with channels through which the air flow from the outlet 16 of the duct 12 is intended to circulate so as to optimize the cooling of the brake discs. By placing the outlet surface 16 of the duct 12 close to the bowl of the brake disc, between the pivot and the caliper 9, the air flow from the outlet 16 of the duct 12 is brought precisely and efficiently to the braking device 4 to be cooled. In addition, the air at the outlet of the duct 14 may be directly directed to where its use will be relevant, for example at the caliper 9 or the brake pads of the braking device 4.

[0040] Furthermore, the outlet 16 of the duct 12 may be 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, thus optimizing its cooling. Such a configuration is notably illustrated 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.

[0041] According to an advantageous embodiment which is also illustrated in this same figure 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 air flow F leaving the duct 12 is always directed towards the braking device 4, independently of the position of the wheel 17 of the motor vehicle 1. The cooling of the braking device 4 is thus optimized in all circumstances.

[0042] In the example illustrated in Figure 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 Figure 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 unit 8.

[0043] 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 removable 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 in particular makes it possible to replace only the flexible part 15 of the conduit 12 which is a priori more likely to wear than the rigid part 13 of the conduit 12.

[0044] According to another embodiment, as illustrated in FIG. 5, the arrangement 2 may comprise a scoop 18 configured to direct the air flow 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 fixed 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.

[0045] Finally, the duct 12 and the scoop 18 can be coupled. This allows the condit 12 to be kept in a single rigid part. The scoop 18 is then placed in the extension of the duct 12 in order to guide the air flow F as close as possible to the braking device 4.

[0046] In general, the arrangement 2 for cooling the braking device 4 does not require a separate cooling system, which makes it possible to dispense with separate air guide channels to the wheel brakes 17. Such an arrangement 2 can furthermore avoid the arrangement 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 the latter is used for travel.

[0047] The invention is not limited to the front wheel arches 17 of motor vehicles 1, and can of course be applied in a similar manner to the rear wheel arches, preferably in combination with an engine unit arranged at the rear of the motor vehicle 1.

[0048] Alternatively, the above arrangement could also be applied to vehicle typologies having air inlets located in the center of the vehicle.

[0049] Such an arrangement 2 for cooling a braking device 4 of a motor vehicle 1 may in particular be used for implementing a method for 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.

[0050] This method of cooling a braking device 4 is carried out when the vehicle is in a rolling situation or stopped. Furthermore, this cooling method takes into account the thermal state of the braking device 4 when the vehicle 1 is stopped, but in a state of awakening of the electronic components controlling the functional organs, such as those controlling the operation of the motor-fan unit 8.

[0051] This method comprises 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 higher than the predefined threshold, a step of activating the fan 7 of the motor-fan unit 8 of the arrangement 2 as described previously.

[0052] The efficiency of this process can be increased by applying the scoop 18 which will allow the air from the fans to be directed more efficiently towards the braking system.

[0053] In the case where the vehicle 1 equipped with a cooling arrangement 2 as described previously 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 exchanger 6, and / or at the level of a grille, it may be provided in the cooling method to open the controlled flap(s) of the front face of the vehicle 1 in parallel with the activation of the fan 7 of the motor-fan unit 8.

[0054] The step of activating the fan 7 of the motor-fan unit 8 of the arrangement 2 as described above can also be triggered forcibly by a user of the motor vehicle, such as the driver. In this case, the driver can voluntarily control the cooling of the braking system when stopping the vehicle in anticipation of a particular use, such as use on a track. This manual control can be carried out via an interface or a dedicated button, for example.

[0055] 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 carried out from a physical sensor or on the basis of 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.

[0056] As a guide, the predefined threshold for the second step of the process, where the measured or estimated temperature is compared to the threshold, is set, for example, at 300°C. Other threshold values ​​can be considered.

[0057] In this cooling method, several activation levels can be envisaged for the motor-fan unit 8 depending on the change in 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 increase despite a first-level activation of the motor-fan unit 8, an activation of a higher level (for example a second-level activation when the temperature has exceeded a threshold of 400°C) can take place. As long as the temperature increases, a higher activation level than the previous level can be envisaged, up to the maximum activation level. Conversely, when the temperature drops, a downgrade of the activation level of the motor-fan unit 8 can be carried out until the temperature falls back below the predefined initial threshold, for example 300°C.In this cooling method, the fan 7 of the motor-fan unit 8 of the arrangement 2 is deactivated when the measured temperature is lower than the predefined threshold.

[0058] 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.

[0059] Depending on the result of the comparison of the measured or estimated temperature with the predefined threshold, the fan 7 of the motor-fan unit 8 of the arrangement 2 for cooling a braking device 4 is activated, or even controlled to a higher or lower activation level. Similarly, the controlled shutters will be opened if they were previously closed. To do this, a computer can be kept awake when the vehicle is stationary to monitor the evolution of the temperature of the braking device 4.

[0060] 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 method, for example repeating the first step and the second step every ten seconds for a given period, then every thirty seconds for another period during the same implementation of the method for cooling a braking device.

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 group motor fan (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 conduit (12), the scoop (18) being configured to orient a 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 connected to each other 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 dimensions smaller 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 to 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 claims previous steps, and repetition of 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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