Patent Description:
This invention applies to the technical field of automotive braking systems comprising the use of a brake pedal connected to a respective lever.

The brake pedal lever, under normal operating conditions, is held in an idle position. When it is in this position, the braking system does not apply any braking action.

In the event of an accident, however, the pedal lever is a potential hazard for the driver, who, in the event of an impact with it, risks suffering from physical damage (e.g. typically fractures to the leg and/or foot bones).

To solve this problem, pedal solutions exist in the prior art which comprise mechanically collapsible parts; such solutions are difficult to implement because said components could be subject to collapse also due to stresses caused by external forces, present in normal conditions of use, e.g. such as road surface irregularities. Such solutions cannot discriminate between stresses due to accidental impacts and those caused by normal conditions of use (uneven asphalt, potholes, off-road driving) => unintended collapse.

Furthermore, they do not always guarantee an immediate collapse of the lever and thus do not always avoid the risk of physical damage to the driver because it is necessary to exceed a threshold value of the impact force between the limb and the pedal itself for it to collapse. Obviously, for safety reasons, such a threshold value cannot be low, otherwise there would be a risk of dangerous "false activations" in the event of, for example, uneven ground, holes, stones and the like. Solutions according to cited prior art are disclosed by <CIT>, <CIT> and <CIT>.

Therefore, the need is felt to solve the drawbacks and limitations mentioned above with reference to the prior art.

Such a need is met by a braking system for vehicles with collapsible actuation pedal according to claim <NUM> and by an actuation method of a braking system in case of impact according to claim <NUM>.

In particular, such a requirement is met by a braking system for vehicles with a collapsible actuation pedal, comprising.

characterized in that
the hydraulic branch is arranged in series and downstream relative to the accumulator device.

According to a possible embodiment, said detector is, for example, an airbag controller, which supervises the operation of at least one airbag, and wherein the control actuator is operatively connected to said controller, to actuate the control valve to open when the airbag controller commands the activation of said airbag.

According to a possible embodiment, the airbag controller is connected to an explosive charge which acts as an actuator of the control valve, so that the explosive charge can directly activate the opening of the control valve.

According to a possible embodiment, the control valve is a pressure relief valve, and the control actuator comprises a second accumulator device, arranged in series and downstream of said accumulator device.

According to a possible embodiment, the braking system comprises at least one electro-hydraulic or electro-mechanical actuator connected to at least one braking device, which controls the actuation of the braking device as a function of the actuation pedal stroke.

According to a possible embodiment, the braking system comprises a safety valve which, in the event of an electrical fault of said electro-hydraulic or electro-mechanical actuator, fluidically connects the delivery circuit with at least one braking device.

The present invention also relates to an actuation method of a braking system in case of impact comprising the steps of:.

Further features and advantages of the present invention will be more comprehensible from the following description of preferred embodiments given by way of nonlimiting examples, in which:.

Elements or parts in common to the embodiments described will be indicated hereafter using the same reference numerals.

With reference to the aforesaid figures, reference numeral <NUM> globally indicates a braking system, as described in greater detail below.

The braking system is preferably, but not necessarily, of the brake-by-wire type.

For the purposes of the present invention, the specific type of braking devices employed in the braking system (not shown), which usually, but not necessarily, comprise disc or drum brakes, is not relevant.

The braking system <NUM> comprises a collapsible actuation pedal <NUM> operatively connected to a hydraulic master cylinder <NUM> having a delivery circuit <NUM> fluidically connected to an accumulator device <NUM>.

The accumulator device <NUM> is a device configured to simulate the pedal resistance provided by a conventional hydraulic brake system. The accumulator device <NUM> may also be a reservoir or pressure fluid accumulator.

Advantageously, the delivery circuit <NUM> comprises a hydraulic branch <NUM> provided with at least one normally closed control valve <NUM>.

According to an embodiment, said control valve <NUM> is connected to a control actuator <NUM> which controls its opening upon detection of an impact or incident by an appropriate detector <NUM> (trigger). Preferably, said detector <NUM> is an airbag controller, which supervises the operation of at least one airbag, said control actuator <NUM> being, in turn, operatively connected to said airbag controller <NUM>, to actuate said control valve <NUM> to open when said airbag controller commands the activation of said airbag.

In this manner, if the airbag controller <NUM> detects an impact of a given intensity, it commands the control actuator <NUM> to open the control valve <NUM>, releasing the pressure, i.e. depressurizing the delivery circuit. In this manner, if the driver's foot were to impact against the actuation pedal <NUM>, the pedal would not offer any resistance and it would collapse, i.e. it would fall without causing injury to the driver.

According to a further possible embodiment (<FIG>), the airbag controller <NUM> is provided with an explosive charge <NUM> which acts as a control actuator <NUM> of the control valve <NUM>, so that the explosive charge can directly activate the opening of the control valve <NUM>. The depressurization of the pressure circuit <NUM> is particularly rapid in this embodiment.

According to a further embodiment (<FIG>), said control valve <NUM> is calibrated to open automatically upon reaching a pressure and/or flow limit value in the hydraulic branch <NUM> following lowering of the actuation pedal <NUM>.

In other words, if the user's foot or leg were to accidentally impact against the actuation pedal <NUM>, causing the sudden lowering of the pedal and thus increasing the delivery pressure of the hydraulic master cylinder <NUM> in the delivery circuit <NUM>, the control valve <NUM> would open automatically when said pressure and/or flow rate limit value is reached; in this case, the actuation pedal <NUM> would lower abruptly, ceasing to offer resistance and preventing damage to the user's foot or leg.

The hydraulic branch <NUM> is arranged in series and downstream with respect to the accumulator device <NUM>. Furthermore, the control valve <NUM> is a pressure relief valve and the control actuator <NUM> comprises a second accumulator device <NUM>, arranged in series and downstream of said accumulator device <NUM>.

In this manner, the second accumulator device <NUM> acts as a pressure limiter of the pressure circuit <NUM>; again in this case, if the user's foot or leg were to accidentally impact against the actuation pedal <NUM>, causing the sudden lowering of the pedal and thus increasing the pressure in the pressure circuit <NUM>, the second accumulator device, which acts as a control valve <NUM>, would cause the pressure downstream of the hydraulic master cylinder to drop suddenly to lower the actuation pedal <NUM>.

As mentioned above, the brake system <NUM> is preferably of the brake-by-wire type.

Furthermore, the braking system <NUM> comprises at least one electro-hydraulic or electro-mechanical actuator connected to at least one braking device (not shown), which controls the actuation of the braking device as a function of the actuation pedal stroke.

According to a possible embodiment, the braking system <NUM> comprises a safety valve (not shown) which, in the event of an electrical fault of said electro-hydraulic or electro-mechanical actuator, fluidically connects the delivery circuit with at least one braking device. In this manner, in the event of an electrical fault, it is guaranteed that the user can brake by directly actuating at least one braking device by means of the hydraulic fluid pressurized by the hydraulic master cylinder.

The operation of a braking system according to the present invention will now be described.

The actuation method of a braking system in case of impact comprises the steps of:.

In detail, the operating principle is based on the fact that in case of the accidental impact of the user's foot or leg against the activation pedal <NUM>, the pedal will offer an increasing resistance because it will increase the delivery pressure in the delivery circuit <NUM> to which the activation pedal <NUM> is connected by means of the hydraulic master cylinder <NUM>. When the resistance offered by the drive pedal <NUM> exceeds a given threshold, the pedal constitutes a hazardous obstacle for the foot/leg of the user, who may suffer from serious trauma.

On the other hand, the brake system <NUM> according to the invention provides for depressurizing the delivery circuit <NUM> to obtain the sudden lowering of the actuation pedal <NUM> upon impact against the user's foot and/or leg.

Thus, the brake pedal lever is depressurized in the event of an accident to reduce its potential hazard to the driver.

In this manner, in the event of an accidental impact of the leg against the brake pedal in the rest position, the pedal will offer practically no resistance because the pressure in the system downstream of the pedal is significantly reduced: therefore, the pedal will sink under the thrust of the leg without causing injury or fractures.

The depressurization may be active or passive.

In the first case (<FIG> relative to embodiments not being part of the present invention), the detector <NUM>, which actively detects potential danger due to an impact such as to require airbag deployment, can be exploited. Such an activation takes place at the same time as that of the control valve <NUM> which discharges the delivery pressure downstream of the hydraulic master cylinder <NUM>. Further, as seen, the activation may comprise using a control actuator <NUM> which acts on the control valve <NUM>, opening it at least partially.

For a sudden activation, it is also possible to provide for the use of an explosive charge of the detector <NUM> in order to open, at least partially, said control valve <NUM>.

The depressurization can also be passive.

In such a case (<FIG> according to the invention), the control valve <NUM> opens automatically as soon as a given threshold pressure is reached in the flow circuit <NUM>, following the lowering of the actuation pedal <NUM>.

As can be appreciated from the description above, the present invention makes it possible to overcome the drawbacks presented in the prior art.

Indeed, the suggested solution provides the depressurization of the brake pedal lever as soon as it is recognized that the vehicle is involved in a traffic accident. In this manner, the brake lever will not oppose resistance to pressure and, in the event of an accidental impact by the driver, will be free to move from its rest position. The implementation of the present invention will thus drastically reduce the risk of injury from accidental impact with the brake pedal lever by the driver.

Claim 1:
Braking system (<NUM>) for vehicles with collapsible actuation pedal, comprising
- an operating pedal (<NUM>) operatively connected to a hydraulic pump (<NUM>) having a delivery circuit (<NUM>) fluidically connected to an accumulator device (<NUM>), wherein
- the delivery circuit (<NUM>) comprises a hydraulic branch (<NUM>) equipped with at least one normally closed control valve (<NUM>),
- said control valve (<NUM>) being connected to a control actuator (<NUM>) which commands its opening when an impact or accident is detected by a special detector (<NUM>) or being calibrated to open automatically when a limit pressure and/or flow rate value is reached in the hydraulic branch (<NUM>) following the lowering of the actuation pedal (<NUM>),
characterized in that
the hydraulic branch (<NUM>) is arranged in series and downstream of the accumulator device (<NUM>).