Heating an electronically controlled pneumatic parking brake system for a vehicle

Abstract

An electronically controlled pneumatic parking brake system (305) for a vehicle (100) is described, comprising a control device (300) that generates electronic signals to apply and release the parking brake (360). This system utilizes an air supply source (230) and two electropneumatic valves (210, 220) for brake operation. The first valve (210) releases the brake by admitting pressurized air into a control chamber (260) upon receiving a release signal, whereas the second valve (220) activates the brake by venting air to atmosphere upon receiving an actuation signal. The control device (300) is also capable of detecting malfunctions in these valves and can perform a recovery function to heat the valves (210, 220) to restore their function.After recovery, the controller uses a PWM signal generator (301) to repeatedly apply and release the brake by alternately operating the valves (210, 220).

Description

Technical field

[0001] This document discloses heating parts of an electronically controlled pneumatic parking brake system for a vehicle according to the appended claims. background

[0002] In vehicles in general, a parking brake solution is often applied when the vehicle is parked in a stationary position to prevent the vehicle from rolling during unattended parking, which can lead to serious accidents. The parking brake is important for all types of vehicles, but perhaps especially for heavier vehicles such as trucks, buses, and combination vehicles, as the consequences of an accident are severe.

[0003] In the case of a manned vehicle, the vehicle often has a handbrake system that could be activated by the driver via a parking brake control located in the vehicle's cab. Upon activation of the parking brake control, air is released from a spring brake chamber / pneumatic brake circuit, and springs acting on the vehicle's brakes apply a load to the brakes, thereby preventing the vehicle's wheels from rolling.

[0004] A problem with parking brakes in general is that they can freeze in sub-zero temperatures (Celsius), causing them to either lock in a released position, making it impossible to apply the parking brake; or alternatively, lock in an applied position, making it impossible to release the parking brake.

[0005] If the brakes freeze in the applied position after parking, transport of the vehicle will be delayed and the vehicle may need to be towed to a garage or similar location for de-icing.

[0006] It appears that further improvements are needed to increase parking safety and address issues related to frozen

[0007] To eliminate or at least reduce the impact of a vehicle's parking brakes in cold weather conditions. Summary

[0008] It is therefore a task to solve at least some of the above problems and to provide a safe parking brake solution for a vehicle even in cold temperatures below zero degrees Celsius.

[0009] The features claimed in the appended claims may advantageously be used as a supplement to a parking brake recovery function such as that described herein. (The brake recovery function is the subject of a separate patent application by the same applicant.) Alternatively, the claimed features may, if desired, be used separately or in combination with other types of parking brake heating concepts.

[0010] According to a first aspect of the invention, this object is achieved by an electronically controlled pneumatic parking brake system for a vehicle. The system comprises a control device configured to generate an electronic brake actuation signal when it receives an indication that a parking brake is to be applied / activated. The control device is further configured to generate an electronic brake release signal when it receives an indication that the parking brake is to be released / deactivated.

[0011] The system also includes an air supply source for supplying compressed air. Furthermore, the system includes a first electropneumatic valve connected to the control device for data transmission and connected to the air supply source and to a control chamber. The first electropneumatic valve is capable of releasing the parking brake by opening the first electropneumatic valve, thereby allowing compressed air to flow through the first electropneumatic valve into the control chamber when the electronic brake release signal is received from the control device.

[0012] In addition, the system includes a second electropneumatic valve connected to the control device for data transmission and connected to the control chamber and an exhaust port. The electropneumatic valves may, for example, comprise solenoids such as bistable solenoids or any similar technical solution. The second electropneumatic valve is capable of activating the parking brake by opening the second electropneumatic valve, thereby releasing compressed air from the control chamber to atmosphere via an exhaust port when the electronic brake application signal is received from the control device.

[0013] The control device is designed to detect that the first electropneumatic valve and / or the second electropneumatic valve has / have a malfunction.

[0014] The control device may be capable of obtaining information indicating a pressure in a spring brake chamber of the parking brake and / or the pressure in a unit pneumatically connected to the spring brake chamber. The detection of the malfunctioning first electropneumatic valve and / or second electropneumatic valve may be performed based on the obtained pressure information.

[0015] If one of the valves is blocked by ice, the pressure in the parking brake's spring brake chamber may deviate from the expected value. Measuring the pressure with a pressure sensor provides reliable detection when the pressure in the spring brake chamber deviates from the expected pressure indicated by the hand control unit.

[0016] Furthermore, the control device is configured to perform a recovery function to heat the first electropneumatic valve and the second electropneumatic valve, thereby melting any ice formations that may have caused an obstruction to the function of the electropneumatic valves.

[0017] The heating of the recovery function can be achieved, for example, by activating an electronic heater arranged on the electropneumatic valves; a heat exchanger that provides a heated fluid in the immediate vicinity of the electropneumatic valves; or by controlling a pulse width modulation (PWM) signal generator to generate PWM signals.

[0018] The control device is further configured to, when the electropneumatic valves have been restored by heating the restoration function, control the PWM signal generator to alternately generate and provide a PWM signal having an operating duty cycle for the first electropneumatic valve and the second electropneumatic valve to repeatedly apply and release the parking brake by alternately opening and closing the first electropneumatic valve and the second electropneumatic valve.

[0019] Moisture accumulated in the system can eventually turn into ice in cold weather conditions below zero degrees Celsius. The moving parts in the valves are particularly susceptible to freezing. If they are frozen, the function of the parking brake is compromised, as the parking brake states (released / applied) are transitioned via the valves. By intentionally heating the valves when a malfunction is detected, any ice that has formed in the valves is melted / evaporated. However, the melted ice / water / moisture may remain in / on the valves. If the vehicle remains in sub-freezing temperature conditions, the water will turn back into ice when heating is interrupted and the temperature at the valves drops below the freezing / crystallization point.

[0020] Repeatedly applying and releasing the parking brake allows compressed air to flow through the respective electropneumatic valves, blowing water / moisture away from and around the electropneumatic valves. Refreezing of the melted ice / water in the valves is prevented because the melted water is drained from the area around the valves.

[0021] Reliable parking brake function is ensured even in cold climates and weather conditions, thus ensuring road safety.

[0022] Optionally, the recovery function for heating the electropneumatic valves may include controlling the PWM signal generator to generate and provide the PWM signal with the same or a similar duty cycle for the first electropneumatic valve and the second electropneumatic valve to heat the valves. The function of the electropneumatic valves may thereby be restored. The duty cycle may be suitable for actuating the electropneumatic valves.

[0023] One advantage of heating the electropneumatic valves using the PWM signal generator that provides the PWM signal, compared to using a dedicated heating device such as a heat exchanger or an electronic heater, is that no additional hardware is required, as the PWM signal generator is already present in the vehicle to open / close the electropneumatic valves (if they are not frozen). This reduces costs and vehicle weight.

[0024] Another advantage is that if the recovery function is not installed during vehicle production, it could be provided via a software update. Many vehicles, if not most vehicles worldwide, will never drive in sub-zero temperatures, and therefore the recovery function may not be installed / activated in the vehicle. For example, if a vehicle is driven or exported from a Mediterranean environment to northern Scandinavia, the owner can download and install the recovery function (possibly also the pre-recovery function and / or the continuous heating function).

[0025] This allows the vehicle's functions to be continuously adapted to the current vehicle environment. This avoids installing or maintaining irrelevant programs / services in the vehicle. However, relevant functions such as heating / restoring brakes in sub-zero temperatures could be provided to the vehicle as needed.

[0026] Optionally, the control device can be designed to control the PWM signal generator so that the parking brake is repeatedly applied and released several times.

[0027] Optionally, the control device can be configured to obtain information about an ambient temperature. The control device can also be configured to adjust the frequency with which the PWM signal generator should repeatedly apply and release the parking brake based on the ambient temperature.

[0028] The time required to release water / moisture from the valves by repeatedly applying and releasing the parking brake is thereby optimized in relation to temperature.

[0029] Optionally, the control device can be configured to detect a risk of water freezing on the electropneumatic valves, for example, based on temperature measurements of an ambient temperature. Furthermore, the control device can be configured to detect that the first electropneumatic valve and / or the second electropneumatic valve is / are malfunctioning if it detects that the ignition is switched on while the vehicle is stationary and the parking brake is applied.

[0030] The control device may further be configured to control the PWM signal generator to generate and provide a PWM signal having an operating duty cycle for the second electropneumatic valve to heat the second electropneumatic valve with the aim of restoring the function of the second electropneumatic valve; wherein the operating duty cycle is suitable for actuating the electropneumatic valves.

[0031] By triggering a preheating of the second electropneumatic valve (i.e., the parking brake application valve) under predefined conditions, i.e., the vehicle is stationary, the parking brake is applied, the first electropneumatic valve and / or the second electropneumatic valve is malfunctioning, and the vehicle's ignition is switched on, the preheating function ensures or at least increases the likelihood of successful application of the parking brake after the parking brake has been released following a subsequent recovery function.

[0032] The total time required to heat the electropneumatic valves sufficiently to melt any ice buildup in the valves is also minimized or at least shortened. The time required to enable the driver to resume driving is reduced.

[0033] Optionally, the control device can be configured to control the PWM signal generator such that it generates and provides the PWM signal with the same duty cycle as in normal operation.

[0034] Providing the PWM signal with the same duty cycle as during normal operation simplifies implementation. A typical duty cycle, for example, might be around 33%. This also keeps the PWM signal duty cycle low and prevents valve overheating. This extends the valves' service life. It's important to note that no additional equipment, such as temperature sensors or any other measures, are required to control valve overheating, which is a major advantage.

[0035] Optionally, the duty cycle can be approximately 20 to 40%.

[0036] It is desirable to avoid overheating the valves while minimizing the heating time required to melt ice buildup in the valve(s). Keeping the duty cycle of the PWM signal between approximately 20 and 40% has been found to be a good compromise for the expected ambient temperatures.

[0037] Optionally, the control device may be capable of obtaining information about an ambient temperature, and wherein the control device may be configured to control the PWM signal generator to generate and provide the PWM signal for a time-limited period. The time-limited period may be adjusted based on the ambient temperature.

[0038] The time limit of the recovery function and / or the length of the duty cycle is thereby optimized with respect to the temperature.

[0039] Optionally, the control device may be capable of detecting a risk of water refreezing at the electropneumatic valves. Furthermore, the control device may be configured to control the PWM signal generator of the first electropneumatic valve and the second electropneumatic valve to generate and provide a PWM signal with a reduced duty cycle for the first electropneumatic valve and the second electropneumatic valve to heat the valves, wherein the reduced duty cycle is lower than that required to actuate the electropneumatic valves.

[0040] By heating the valves when a risk of refreezing water is detected, the temperature at or near the valves is raised above the freezing point of water. This prevents water / moisture / wetness that melted during the previously performed recovery function from refreezing into ice, which can block the valves' function. This ensures reliable operation of the parking brakes even in cold climates / weather conditions if melted ice / water refreezes. Furthermore, road safety is increased.

[0041] Optionally, the control device may be capable of detecting the risk of freezing / refreezing of water at the electro-pneumatic valves based on a comparison between an ambient temperature and a temperature threshold.

[0042] By measuring or otherwise sensing an ambient temperature and comparing it with a relevant temperature threshold such as the freezing point of water (0 degrees Celsius), possibly with a margin, a reliable trigger is achieved to activate the heating of the electro-pneumatic valves.

[0043] Optionally, the reduced duty cycle of the PWM signals provided to the first electropneumatic valve and the second electropneumatic valve generated and provided by the PWM signal generator may be approximately 10 to 15%.

[0044] By applying a reduced duty cycle, significantly lower than that required to actuate the electropneumatic valves, heat is provided to the electropneumatic valves without the risk of actuating the valves. This allows the valves to be heated safely even while driving.

[0045] According to a second aspect of the invention, this object is achieved by a method for a control device of a vehicle having an electronically controlled pneumatic parking brake system according to the first aspect.

[0046] The method includes the step of detecting that the first electropneumatic valve and / or the second electropneumatic valve is malfunctioning. The method also includes obtaining an instruction to heat the first electropneumatic valve and the second electropneumatic valve. The method further includes executing a recovery function to heat the first electropneumatic valve and the second electropneumatic valve.

[0047] The method further comprises, when functions of the electropneumatic valves are restored, controlling a pulse width modulation (PWM) signal generator to alternately generate and provide a PWM signal with an operating duty cycle for the first electropneumatic valve and the second electropneumatic valve. The operating duty cycle is suitable for actuating the electropneumatic valves, for repeatedly applying and releasing the parking brakes by alternately opening and closing the first electropneumatic valve and the second electropneumatic valve.

[0048] Heating the valves when they are suspected of being frozen will melt / evaporate any ice within. Repeatedly applying and releasing the parking brake allows compressed air to flow through the respective electropneumatic valves, blowing water / moisture away from and around the electropneumatic valves.

[0049] Reliable parking brake function is ensured even in cold climates and weather conditions, improving road safety.

[0050] Optionally, the recovery function for heating the electropneumatic valves may comprise controlling the PWM signal generator to generate and provide the PWM signal with the same or a similar duty cycle for the first electropneumatic valve and the second electropneumatic valve to heat the valves, thereby restoring the function of the electropneumatic valves; wherein the duty cycle is suitable for actuating the electropneumatic valves.

[0051] Optionally, the method may also include the step of detecting a risk of water freezing on the electropneumatic valves. The method may further include detecting that the first electropneumatic valve and / or the second electropneumatic valve is / are malfunctioning when, with the vehicle stationary and the parking brake applied, it is detected that the ignition is switched on. Furthermore, the method may also include the step of controlling the PWM signal generator such that it generates and provides a PWM signal with the duty cycle for the second electropneumatic valve in order to heat the second electropneumatic valve with the aim of restoring the function of the second electropneumatic valve. The duty cycle may be suitable for actuating the electropneumatic valves.

[0052] By triggering a preheating of the second electropneumatic valve under predefined conditions, i.e. the vehicle is stationary, the parking brake is applied, the first electropneumatic valve and / or the second electropneumatic valve has / have a malfunction, and the ignition of the vehicle is switched on, it is ensured or at least the probability is increased that a successful application of the parking brake is possible after it has been possible to release the parking brake after a subsequently performed recovery function.

[0053] The total time required to heat the electropneumatic valves sufficiently to melt any ice buildup in the valves is minimized or at least shortened. The time required to enable the driver to resume driving is reduced.

[0054] Optionally, when the function of the electropneumatic valves is restored, the method may include the step of detecting a risk of water refreezing on the electropneumatic valves. The method may further include controlling the PWM signal generator of the first electropneumatic valve and the second electropneumatic valve to generate and provide the PWM signal with a reduced duty cycle for the first electropneumatic valve and the second electropneumatic valve to heat the valves. The reduced duty cycle may be lower than required to actuate the electropneumatic valves.

[0055] According to a further aspect of the invention, this object is achieved by a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method according to the second aspect.

[0056] According to a further aspect of the invention, this object is achieved by a computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method according to the method according to the second aspect.

[0057] According to yet another aspect of the invention, this object is achieved by a vehicle having an electronically controlled pneumatic parking brake system according to the first aspect.

[0058] Other advantages and additional novel features will become apparent from the detailed description below. Figures

[0059] Embodiments of the invention will be described in more detail below with reference to the accompanying figures, in which: Fig. 1 illustrates an embodiment of a vehicle having an electronically controlled pneumatic parking brake system. Fig. 2A illustrates a pneumatic parking brake assembly for a vehicle according to an embodiment in a first state. Fig. 2B illustrates a pneumatic parking brake assembly for a vehicle according to an embodiment in a second state. Fig. 3A illustrates an electronically controlled pneumatic parking brake system in one embodiment, wherein the parking brakes are implemented as disc brakes, in a first state. Fig. 3B illustrates an electronically controlled pneumatic parking brake system in an embodiment, wherein the parking brakes are implemented as disc brakes, in a second state. Fig. 4A illustrates a vehicle interior of a vehicle having an electronically controlled pneumatic parking brake system. Fig. 4B illustrates a vehicle interior of a vehicle having an electronically controlled pneumatic parking brake system. Fig. 4C illustrates a vehicle interior of a vehicle having an electronically controlled pneumatic parking brake system. Fig. 4D illustrates a vehicle interior of a vehicle having an electronically controlled pneumatic parking brake system. Fig. 4E illustrates a vehicle interior of a vehicle having an electronically controlled pneumatic parking brake system. Fig. 4C illustrates a vehicle interior of a vehicle having an electronically controlled pneumatic parking brake system. Fig. 4G illustrates a vehicle interior of a vehicle having an electronically controlled pneumatic parking brake system. Fig. 4H represents a vehicle interior of a vehicle having an electronically controlled pneumatic parking brake system. Fig. 5A to B illustrate a method for a control device of a vehicle having an electronically controlled pneumatic parking brake system in one embodiment. Detailed description

[0060] Embodiments of the invention described herein are defined as an electronically controlled pneumatic parking brake system and method that may be implemented in the embodiments described below. However, these embodiments may be exemplified and implemented in many different forms and are not to be limited to the examples set forth herein; rather, these illustrated examples of embodiments are provided so that this disclosure will be thorough and complete.

[0061] Still other objects and features will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. It should be understood, however, that the drawings are for illustrative purposes only and not as a definition of the limits of the embodiments disclosed herein, for which reference should be made to the appended claims. Further, the drawings are not necessarily drawn to scale and, unless otherwise indicated, serve merely to conceptually illustrate the structures and procedures described herein. Like numerals refer to like elements throughout.

[0062] Fig. 1 illustrates a vehicle 100 having an electronically controlled pneumatic parking brake system.

[0063] For example, vehicle 100 could be or include a truck, a car, a trailer, a bus, an articulated vehicle (comprising a tractor unit and a trailer / semi-trailer), or other similar manned or unmanned (i.e., autonomously controlled) means of transport on a roadway. However, for the sake of clarity, vehicle 100 will be described below as including a driver.

[0064] The vehicle 100 may include a cab 101 in which a driver is normally located during operation of the vehicle 100. In some alternative embodiments, where the vehicle 100 may be driverless, i.e., autonomously controlled, the vehicle 100 may not include a cab.

[0065] The vehicle 100 also includes a drive unit, such as an internal combustion engine, an electric motor, or a combination thereof. Regardless of the type of drive unit, the vehicle 100 includes a pneumatic parking brake assembly.

[0066] The Fig. 2A to 2B illustrate a pneumatic parking brake assembly 200 of the vehicle 100 of Fig. 1 schematically.

[0067] The parking brake assembly 200 is a mechanism for ensuring that the vehicle 100 is held motionless when parked, even when the vehicle 100 has been parked, for example, on a slope or other uneven surface where gravity or an impact, e.g., from another vehicle, could otherwise cause the vehicle 100 to move undesirably by immobilizing wheels of the vehicle 100. The parking brake function is sometimes referred to as a handbrake (to distinguish it from the mechanically independent service brake, primary brake, or foot brake, as it may also be called, which is normally used for braking during propulsion of the vehicle 100). The vehicle 100 may include additional service brakes, auxiliary brakes such as retarders, or a similar system for reducing vehicle speed during propulsion.

[0068] The pneumatic parking brake assembly 200 may include various components, such as an air supply source connection 235 for providing compressed air.

[0069] The pneumatic parking brake assembly 200 has a brake chamber port 375 connected to a spring brake chamber associated with a parking brake.

[0070] The parking brake is released when compressed air is supplied to the spring brake chamber and applied when the compressed air is released from the spring brake chamber. The details of the functions of the parking brake and the spring brake chamber are shown in the Fig. 3A to 3B and the corresponding section of the description and described in more detail.

[0071] In a typical scenario, the vehicle 100 may have one parking brake per wheel set of the vehicle 100. However, in alternative embodiments, only some or one wheel set of the vehicle 100 may have a parking brake. If the vehicle 100 comprises an articulated vehicle, brakes on all or at least some or one of the trailer / semi-trailer brakes may have a respective spring brake chamber.

[0072] The supply of compressed air to the spring brake chamber of the parking brake from the air supply source is controlled by a control device via a first electropneumatic valve 210 and a second electropneumatic valve 220. The electropneumatic valves 210, 220 may comprise a solenoid or other similar means for setting the respective valve 210, 220 in positions to allow / prevent the flow of compressed air by opening / closing the respective electropneumatic valve 210, 220. In other embodiments, additional electropneumatic valves may be provided, for example, for emergency braking or when the vehicle 100 forms part of an articulated vehicle, wherein the additional electropneumatic valves may be provided for the parking brakes of the trailer / semi-trailer.

[0073] The control device may, for example, comprise one or more electronic control units (ECUs), typically a plurality of cooperating ECUs. The control device may comprise a digital computer that controls one or more electrical systems or electrical subsystems of the vehicle 100, for example, based on information read from sensors placed on various parts or in different components of the vehicle 100 and / or signals generated by the driver or an autonomous driving system. The control device is configured to evaluate the obtained sensor detection readings / signals, for example, to compare them with a respective threshold value, and to generate control signals based on the result of the comparison.

[0074] A computer, in the present context, can be considered any hardware or hardware / firmware device implemented using processing circuitry, such as, but not limited to, a processor, a central processing unit (CPU), a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field-programmable gate array (FPGA), a system-on-chip (SoC), a programmable logic unit, a microprocessor, an application-specific integrated circuit, or any other device capable of electronically performing operations in a defined manner.

[0075] The first electropneumatic valve 210 and the second electropneumatic valve 220 are both in communication with the control device via a wired or wireless communication interface.

[0076] Various entities on board the vehicle 100, such as the control device and the electropneumatic valves 210, 220, can transmit data and / or exchange information via a data connection, e.g., via a bus such as a Controller Area Network (CAN) bus, a Media Oriented Systems Transport (MOST) bus, or the like.

[0077] Alternatively, data transmission can occur via a wireless data transmission interface, such as vehicle-to-vehicle (V2V) or vehicle-to-infrastructure (V2I) data transmission. The more common term vehicle-to-everything (V2X) is also occasionally used. Wireless data transmission can then be based on Dedicated Short Range Communications (DSRC) devices. DSRC operates in the 5.9 GHz band with a bandwidth of 75 MHz.

[0078] The first electropneumatic valve 210 is connected to the air supply source 230 and to a control chamber 260. The first electropneumatic valve 210 is capable of releasing the parking brake by opening the valve 210, thereby allowing compressed air to flow through the first electropneumatic valve 210 into the control chamber 260 when an electronic brake release signal is received from the control device.

[0079] The pressure built up in the control chamber 260 by the compressed air acts on a control piston 271 and overcomes the pressure of a spring 272 in a working chamber 270, so that compressed air, also from the air supply source 230, is enabled to flow via a supply chamber 280 and the brake chamber connection 275 into the brake chamber of the parking brake.

[0080] This releases the parking brake and vehicle 100 is ready to start.

[0081] The pneumatic parking brake assembly 200 may also include a control port 290 through which compressed air may be supplied to the control chamber 260 in an emergency if ice blocks the first electropneumatic valve 210 or the first electropneumatic valve 210 fails to function for another reason.

[0082] In the opposite case, when switching from drive to parking, the second electropneumatic valve 220 is opened when it receives a control signal from the control device.

[0083] The second electropneumatic valve 220 is connected to the control chamber 260 and to an outlet opening 250 through which compressed air from the control chamber 260 can be released to the atmosphere. The second electropneumatic valve 220 is capable of activating the parking brake by opening the valve 220, thereby releasing the compressed air from the control chamber 260 to the atmosphere via the second electropneumatic valve 220 when the electronic brake actuation signal is received from the control device, as shown in Fig. 2B. When the compressed air is released from the control chamber 260, the working chamber spring 270 closes the compressed air supply from the supply chamber 280 to the outlet / spring chamber port 275 and instead opens the spring brake chamber port 275 to the atmosphere via the exhaust port 250.

[0084] This allows compressed air in the spring brake chamber of the parking brake to be vented to atmosphere through the outlet opening 250. When atmospheric pressure prevails in the spring brake chamber, the parking brake is activated.

[0085] The Fig. 3A to 3B schematically illustrate an electronically controlled pneumatic parking brake system 305 having various components that cooperate with the pneumatic parking brake assembly 200, such as a hand control unit 310, a spring brake chamber 320, and a parking brake 360 ​​having friction pads 350 in a brake caliper capable of acting on a disc 351 fixedly mounted on a wheel axle 361.

[0086] The vehicle 100 may have the same type of brakes on all axles / wheels, for example, disc brakes on all axles / wheels; or alternatively, drum brakes on all axles / wheels.

[0087] The vehicle 100 may have one type of brakes on the front axle(s) and another type of brakes on the rear axle(s) and wheels; for example, disc brakes may be used on the front axle(s) and wheels, while drum brakes may be used on the rear axle(s).

[0088] In the schematic representation in Fig. 3A to B, the parking brake 360 ​​is represented by a disc brake.

[0089] The electronically controlled pneumatic parking brake system 305 may include a hand-held control unit 310 in some embodiments where the vehicle 100 is driven by a human driver. The hand-held control unit 310 may be physically located within the cab 101 of the vehicle 100 at a convenient location that the driver can reach without undue ergonomic interference, preferably while seated in the driver's seat. When the electronically controlled pneumatic parking brake system 305 is used as an emergency brake in an emergency situation, it may be important to enable the driver to easily locate and pull / operate the hand-held control unit 310.

[0090] The hand control unit 310 may include a manually operable actuator for actuating the parking brake 360. According to examples, the hand control unit 310 may include, for example, a button, a lever, a handle, or other similar device.

[0091] The hand control unit 310 may comprise a hand lever that can be set / adjusted to an inactive position a while the vehicle 100 is driving, ie, the parking brake is released, thereby allowing the wheels of the vehicle 100 to roll. This is shown in Fig. 3A.

[0092] Alternatively, the hand control unit 310 can be set to an active position β when the vehicle 100 is to be parked. The parking brake 360 ​​of the vehicle 100 is activated, thereby immobilizing the wheels of the vehicle.

[0093] Fig. 3A illustrates a situation in which the vehicle 100 is moving and the parking brake 360 ​​is released. If the vehicle 100 has a driver and a hand control unit 310, the hand control unit 310 is then placed in the inactive position a.

[0094] An electronic brake release signal may then be provided to the control device 300. The control device 300 may, in turn, generate a control signal to a pulse width modulation (PWM) signal generator 301 to generate and provide a PWM signal to be provided to the first electropneumatic valve 210 to open the valve 210.

[0095] PWM is a technique used to provide a pulsating signal. The PWM signal is essentially a square wave, meaning it toggles between on and off. What makes a PWM signal unique is the length of time the signal remains on or off. This is called the signal's duty cycle.

[0096] The first electropneumatic valve 210 is then at least temporarily opened, allowing compressed air from the air supply source 230, which is provided via an air supply source port 235 and the outlet / spring chamber port 275, to the spring brake chamber 320.

[0097] Compressed air is allowed to enter / fill the spring brake chamber 320, which exerts pressure on a spring 330 via an airtight seal / diaphragm 335 in the spring brake chamber 320. The compressed air in the spring brake chamber 320 overcomes the spring force of the spring 330 as long as compressed air is retained in / provided to the spring brake chamber 320.

[0098] A physical connecting linkage 340 between the spring 330 and at least one of the friction pads 350 is thereby pulled away from the disc 351, thereby releasing the brake 360 ​​and allowing the wheel / wheel axle 361 to rotate freely without obstruction.

[0099] The controller 300 is configured to adjust the duty cycle, thereby controlling how much power is delivered to the electropneumatic valves 210, 220. A higher duty cycle means more power, since the signal is on for a longer time. A lower duty cycle means less power.

[0100] The PWM signal generator 301 operates by switching between full power transfer and no power transfer. Therefore, the PWM signal generator 301 outputs either 1 or 0 depending on the duty cycle. The duty cycle is the amount of time the signal remains in the "on" state during each cycle. This can be expressed as a percentage. For example, a duty cycle of 50% means the signal is on half the time and off the other half. If the duty cycle is 30%, the signal is on 30% of the time and off 70% of the time. If a pulse frequency is high enough, no power interruptions occur at all, and the electropneumatic valves 210, 220 continue to operate normally, but consume less power compared to a constant voltage supply.

[0101] The PWM signal generator 301 is configured to generate the signal corresponding to the duty cycle in a pulse train upon receiving the control signal from the control device 300. This is accomplished by switching a voltage (or current) on and off at a specific frequency according to the duty cycle. When the signal is "on," it has a maximum value (e.g., +5 or +10), and when it is "off," it has a minimum value (e.g., zero, -5, or -10). Thanks to the PWM signal generator 301 and the PWM signal provided to the electropneumatic valves 210, 220, precise control of the power output to the electropneumatic valves 210, 220 is achieved.

[0102] By providing an optimal PWM signal, for example with a duty cycle of about 33% at the specific frequency, energy consumption can be minimized, overheating of the electropneumatic valves 210, 220 is avoided, and the service life of the components involved is extended.

[0103] Fig. Figure 3B illustrates the electronically controlled pneumatic parking brake system 305 having the same components as previously shown in Fig. 3A. However, in this scenario, the parking brake 360 ​​is applied.

[0104] Accordingly, the manual control unit 310 is set to the active position β. The flow of compressed air from the compressed air supply source 230 is interrupted because the second electropneumatic valve 220 is at least temporarily opened, allowing the compressed air retained in the spring brake chamber 320 to be released into the atmosphere.

[0105] When no compressed air is retained in the spring brake chamber 320, the spring force of the spring 330 causes a pressure effect on the friction linings 350 in the direction of the disc 351 of the disc brake 360, so that rotational movement of the wheel / axle 261 is prevented.

[0106] Thanks to the function of the spring brake chamber(s) 320, the parking brake 360 ​​is automatically activated and applied when a leak in the air supply or any other irregularity in the air pressure occurs and / or when the compressed air supply source 230 runs out of compressed air. A compressor can then be activated to refill the compressed air supply source 230 with compressed air before the parking brakes 360 can be released.

[0107] The Fig. 4A to 4H schematically illustrate a vehicle interior of a vehicle 100 having an electronically controlled pneumatic parking brake system 305, such as that shown in Fig. 1 vehicle shown 100.

[0108] The proposed solution includes detecting that the first electropneumatic valve 210 and / or the second electropneumatic valve 220, or alternatively, the parking brake, is malfunctioning. It can be assumed that the cause of the malfunction is ice formation in the electropneumatic valves 210, 220, for example, based on a temperature estimate.

[0109] In a scenario where the vehicle 100 has been parked outside in low temperatures, the driver may enter the vehicle 100 and start the engine. If the first electropneumatic valve 210 and / or the second electropneumatic valve 220 are detected to be malfunctioning, it may be concluded that the reason is that they are frozen. A low temperature in this context may be below or close to 0 degrees.

[0110] A preheating function can then be triggered to achieve successful parking brake application after the parking brake has been released following the subsequent recovery function. This also reduces the time the driver / vehicle 100 would have to spend at a standstill before it can start.

[0111] It can be inferred that when the ignition is switched on, the driver intends to start driving the vehicle 100 shortly. However, this is not always the case; the driver may switch on the ignition, for example, to access the vehicle's navigation or entertainment module; to perform a safety test (for example, to check the headlights' function), and then switch off the ignition and leave the vehicle 100 for a coffee break or for any other reason. The preheating function may then be terminated when the ignition is switched off or paused until the next time the ignition is switched on.

[0112] The preheating function includes generating and providing a PWM signal with an operating duty cycle for the second electropneumatic valve 220 to heat the second electropneumatic valve 220, with the goal of restoring the function of the second electropneumatic valve 220 by heating and thereby melting the ice buildup on the second electropneumatic valve 220. The applied operating duty cycle is suitable for actuating the electropneumatic valves 210, 220, i.e., the same duty cycle normally used for actuating the electropneumatic valves 210, 220. The operating duty cycle can be set to a value within an interval of 20% to 40%, for example, to approximately 33%.

[0113] Information relating to the detected frozen parking brake may be output to the driver on an output device 410 in the cab 101, as shown in Fig. 4A. The driver is informed of the frozen brake condition and prompted to initiate recovery action by chocking the vehicle and releasing the parking brake.

[0114] The recovery function includes heating the first electropneumatic valve 210 and the second electropneumatic valve 220. The heating may be performed, for example, by activating an electric heater or any other structure for providing thermal energy.

[0115] The electric heating device may be located on or in close proximity to the electropneumatic valves 210, 220. The electric heating device is designed to provide heat energy to the valves 210, 220 to prevent or mitigate condensation and / or freezing. These problems are particularly common in low-temperature and / or high-humidity environments and may impair the function of the valves 210, 220 or cause malfunctions.

[0116] The electric heater may comprise or be made of resistive materials such as nichrome (nickel-chromium) or the like. When an electric current flows through this element, it heats up due to electrical resistance. This can be achieved by arranging the electric heater near or integrated into the valves 210, 220, typically around areas therein that are prone to freezing.

[0117] The heating device can be operated electrically, either from an external power source or from the control system of the valves 210, 220.

[0118] The inclusion of an electric heating device in the electropneumatic valves 210, 220 increases the reliability and efficiency of the parking brakes 360, especially under difficult environmental conditions.

[0119] Heating according to the recovery function can alternatively be performed by operating the PWM signal generator 301 to generate and provide the PWM signal with the duty cycle also for the first electropneumatic valve 210, in order to heat the first electropneumatic valve 210 in addition to the already initiated heating of the second electropneumatic valve 220, the preheating function, with the aim of restoring the function of both the first electropneumatic valve 210 and the second electropneumatic valve 220. The duty cycle applied during recovery can be the same as that applied during the preheating function, i.e., the duty cycle can be set to a value within an interval of 20% to 40%, or approximately 33%.

[0120] In some embodiments, the PWM signal generator 301 may be instructed to adjust the duty cycle of the PWM signal based on the ambient temperature, with an active phase of the duty cycle being extended at lower ambient temperatures and vice versa.

[0121] For example, if the ambient temperature is below -20 degrees, the duty cycle can be set to 40%; if the ambient temperature is about -20 to -10 degrees, the duty cycle can be set to 30%; if the ambient temperature is about -10 to 0 degrees, the duty cycle can be set to 20%; etc.

[0122] If at least one implicit signal is received that the driver wants to execute the recovery function, the recovery function can start and can provide information similar to that in Fig. 4B. The wording "test" may be interpreted as or replaced by: "brake recovery program," "brake defrost program," or a similar expression.

[0123] For safety reasons, it may be necessary for the driver to be present in the cab 101 during heating of the electropneumatic valves 210, 220, for example, by holding down the service brake pedal. This prevents the vehicle 100 from (accidentally) starting to roll if the driver performs the recovery function and the parking brake is suddenly released when the ice on the electropneumatic valves 210, 220 melts.

[0124] The time limit for applying the recovery function may be, for example, 10 to 60 seconds or 1 to 5 minutes (may depend on an ambient temperature). In one embodiment, the recovery function may last approximately 1 minute, during which the PWM signal with the determined duty cycle is provided to the electropneumatic valves 210, 220. The recovery function may then be terminated when the electropneumatic valves 210, 220 begin operating, or alternatively, interrupted when the time limit is reached. In the latter case, the driver may be prompted to repeat the recovery function.

[0125] In some embodiments, other conditions may also exist for interrupting the recovery function. One such reason may be the driver releasing the service brake pedal, opening the door, and / or exiting the vehicle 100. The interruption may then be for safety reasons, as it may be dangerous if the parking brake 360 ​​is released while no driver is in the cab 101. A message similar to that in Fig. 4F may be output to inform the driver of the interruption of the recovery function.

[0126] Another reason for the recovery function to be interrupted is that the driver changes his plans and turns off the ignition and takes another coffee break. A message similar to the display of Fig. 4D can be issued to the driver informing him / her that the recovery function is interrupted.

[0127] The recovery function may also be interrupted for safety reasons if the driver releases the parking brake. Information similar to that in Fig. 4E shown.

[0128] Alternatively, the recovery function can be activated when a time limit is reached, see Fig. 4G, and / or too many repeated attempts, see Fig. 4H, may be interrupted. If the function of the electropneumatic valves 210, 220 has not been restored within the time limit, it can be concluded that there is another problem with the parking brake and the vehicle 100 may require professional assistance from a mechanic.

[0129] In some embodiments, the time limit of the recovery function can be adjusted based on the ambient temperature. The colder it is, the more heating energy is required to melt the ice. The amount of heat generated by providing the PWM signal to the electropneumatic valves 210, 220 due to Joule's law: Q = I 2 RT, where Q = heat (joules) I = current (amperes) R = resistance of the coil of the electropneumatic valves (Ohm) T = Time (seconds)

[0130] The amount of heat generated is proportional to the duration of the PWM signal provided to the respective coils of the electropneumatic valves 210, 220. This allows the recovery function to be executed for a longer time, the colder it is. For example, the time limit for the recovery function can be set to one minute when the ambient temperature is around / below zero degrees; to 90 seconds when the ambient temperature is around / below -5 degrees; to 2 minutes when the ambient temperature is around / below -10 degrees, etc.

[0131] The vehicle 100 may optionally include a temperature sensor 302, which is provided, for example, for determining an ambient temperature. The temperature sensor 302 may be connected to the control device 300 for data transmission, which in turn may adjust the time limit of the recovery function.

[0132] Alternatively, information about an ambient temperature may be obtained from a source external to the vehicle, such as a temperature sensor or a weather service located at the roadside or elsewhere. Such information could be obtained by the vehicle 100 via a wireless data transmission interface.

[0133] The temperature may alternatively or additionally be estimated based on a combination of knowledge of a geographical position of the vehicle 100, a planned route / destination / direction of travel of the vehicle 100 and knowledge of date / time and statistical data relating to expected temperatures with respect to the date / time at the (current or future) geographical position of the vehicle 100.

[0134] The geographical position can be obtained, for example, from the vehicle's onboard navigation device / GPS unit, from a driver's mobile phone, by capturing images with a vehicle's onboard camera, and by analyzing road signs with dedicated image recognition / computer vision software in the control device. The historical / statistical temperature at the vehicle's 100 geographical position at the same time / season, as recorded in a database, can be used to estimate the temperature.

[0135] In still further embodiments, knowledge of the date / time may be used in combination with the current or future geographical position of the vehicle 100 and weather forecast data relevant to the geographical position in combination with the date / time.

[0136] Alternatively, the temperature can be estimated based on images captured by an onboard image sensor in combination with image recognition software. If snow or ice formations are detected in the image; people are wearing winter clothing; people are exhaling vapor; and / or frost is detected on the vehicle, other vehicles, other structures, etc., it can be concluded that there is a risk of freezing.

[0137] In still further embodiments, the temperature may be estimated based on a heating action performed by the driver, for example, activating a defroster, a parking heater, a cabin heater, a seat heater, etc., since the heating action may typically indicate cold / sub-freezing temperatures.

[0138] When the function of the electropneumatic valves 210, 220 is restored due to the recovery function, a repeated series of application and release of the parking brake 360 ​​is initiated in a wet removal function. The purpose is to remove water, i.e., melted ice, that has melted during the recovery function. When the parking brake 360 ​​is released, the first electropneumatic valve 210 is opened, and when the parking brake 360 ​​is applied, the second electropneumatic valve 220 is opened. This continuously repeated activation of the first electropneumatic valve 210 and the second electropneumatic valve 220 improves the air flow through the pneumatic parking brake assembly 200, which in turn vents water / melted ice that has accumulated near the respective electropneumatic valve 210, 220 to the atmosphere.

[0139] This eliminates or at least reduces the risk of the electropneumatic valves 210, 220 freezing again after a period in an ambient temperature below freezing.

[0140] Information about the ongoing recovery program can also be output to the driver during wet-weather removal, ie, during the repeated series of application and release of the parking brake 360.

[0141] The repeated series of application and release of the parking brake of the wet-weather removal function may be performed over a limited period of time (such as a few seconds or minutes) and / or over a limited number of repetitions (such as between 10 and 50); non-limiting examples.

[0142] If the recovery function is successful and the moisture removal function has been performed, a message similar to the one in Fig. 4C to inform the driver that the vehicle 100 is ready to drive.

[0143] The driver or the corresponding autonomous software is then enabled to begin driving the vehicle 100 toward the intended destination. However, during transport, moisture may accumulate in the pneumatic parking brake assembly 200. If the vehicle 100 is driven in sub-freezing climate conditions, there may be a risk of refreezing of the electropneumatic valves 210, 220.

[0144] Therefore, in some embodiments, upon detection of a risk of water freezing at the electropneumatic valves 210, 220 of the vehicle 100, a continuous heating function may be activated. The continuous heating function may include detection of a risk of water refreezing on / in / near the electropneumatic valve(s) 210, 220, which may freeze into a solid state and block the flow of compressed air or otherwise impair the function of the electropneumatic valves 210, 220.

[0145] This condition is critical for the function of the parking brake 360. In one scenario, the risk of water freezing on the electropneumatic valves 210, 220 may be eliminated when the recovery function, the wetness removal function, and / or the preheat function have been performed, but there may remain a risk of the electropneumatic valves 210, 220 returning to a freezing state after the wetness removal function has been terminated (completed or interrupted) because melted water may refreeze during the recovery function when the vehicle 100 is traveling in cold climate conditions.

[0146] The continuous heating function can be triggered by measuring or estimating an ambient temperature compared to a temperature threshold. The temperature threshold can be set to approximately 0 degrees Celsius in some embodiments. Alternatively, a certain margin can be applied, for example, 1 to 5 degrees above 0 degrees Celsius.

[0147] Once the hazard detection (based on ambient temperature measurements) has occurred, the PWM signal generator 301 of the first electropneumatic valve 210 and the second electropneumatic valve 220 can be controlled by the control device 300 to generate and provide a PWM signal with a reduced duty cycle for the first electropneumatic valve 210 and the second electropneumatic valve 220 to heat the valves 210, 220. The reduced duty cycle is lower than required to actuate the electropneumatic valves 210, 220, i.e., without actuating the electropneumatic valves 210, 220.

[0148] The reduced duty cycle can be set to a value lower than that required to actuate the electropneumatic valves 210, 220, for example, approximately 10 to 15%. The electropneumatic valves 210, 220 are thereby heated without any movement of the valves 210, 220. By increasing the temperature at the electropneumatic valves 210, 220, any water at or near the electropneumatic valve(s) 210, 220 remains in a liquid state, even when ambient temperatures are at or below zero degrees Celsius.

[0149] The heating of the electropneumatic valves 210, 220 described above may continue as long as there is a risk of water freezing / refreezing, i.e., until a non-existent risk of water freezing at the electropneumatic valves 210, 220 is detected, for example based on temperature readings compared with the temperature threshold, a temperature above 0 degrees; and / or the current position of the vehicle 100; and / or no wetness / water is detected inside the parking brake unit.

[0150] Thanks to the proposed solution regarding the continuous heating function, the risk of water refreezing on the electro-pneumatic valves 210, 220 is eliminated, resulting in a safer vehicle when driving at a cold / sub-freezing temperature.

[0151] Fig. 5A to 5B illustrate an example of a method 500 according to an embodiment. The flowchart in Fig. 5A to 5B illustrate the method 500 for a control device 300 of a vehicle 100, wherein the vehicle 100 has an electronically controlled pneumatic parking brake system 305. The purpose of the method 500 is to heat electropneumatic valves 210, 220 present in the electronically controlled pneumatic parking brake system 305. This melts and / or vaporizes ice buildup in the valves 210, 220. The melted / vaporized ice is then removed from the electropneumatic valves 210, 220 by pressurized air released by repeatedly applying and releasing the parking brake 360.

[0152] To enable proper heating of the valves 210, 220 and to remove the melted ice, the method 500 may include a series of steps 501 to 509. However, some of these steps 501 to 509 may also be performed in various alternative ways. Some method steps may only be performed in some optional embodiments; such as steps 501 to 503 and / or 508 to 509. Furthermore, the described steps 501 to 509 may be performed in a slightly different chronological order than the numbering suggests. The method 500 may include the following steps: Step 501, which may be performed in some embodiments, includes detecting a risk of water freezing at the electropneumatic valves 210, 220.

[0153] In some embodiments, information may be output to the driver informing him / her of the risk of freezing of the electropneumatic valves 210, 220.

[0154] The information may be output to the driver on / through an output device 410 in the cabin 101 of the vehicle 100 in the form of text, an illuminated symbol, an image, a movie, a voice message and / or a sound alone or in any combination.

[0155] In some embodiments, instructions may also be issued to the driver to perform / confirm the performance of the brake recovery function.

[0156] Step 502, which may be performed in some embodiments where step 501 has been performed, includes detecting that the first electropneumatic valve 210 and / or the second electropneumatic valve 220 is malfunctioning when the ignition is detected to be turned on while the vehicle 100 is stationary and the parking brake 360 ​​is applied.

[0157] The detection that the first electropneumatic valve 210 and / or the second electropneumatic valve 220 has / have a malfunction may be made based on information obtained that indicates a pressure in a spring brake chamber 320 of the parking brake 360 ​​or the pressure in an entity pneumatically connected to the spring brake chamber 320.

[0158] The pressure in the spring brake chamber 320 may be estimated based on a pressure sensor reading. The pressure sensor may be located in the spring brake chamber 320, in the control chamber 260, at the brake chamber port 275, or at any similar suitable location that reflects the pressure in the spring brake chamber 320.

[0159] Other ways to detect a malfunction of the electropneumatic valves 210, 220 may be to detect a movement of the vehicle 100 when the hand control unit 310 has been set to the active position β, possibly in combination with an estimation of a temperature below 0 degrees Celsius.

[0160] Step 503, which may be performed in some embodiments where step 502 has been performed, includes controlling the PWM signal generator 301 to generate and provide a PWM signal with an operating duty cycle for the second electropneumatic valve 220 to heat the second electropneumatic valve 220, but not the first electropneumatic valve 210, with the goal of restoring the function of the second electropneumatic valve 220. This may be referred to as a preheating procedure / function. The operating duty cycle may be suitable for actuating the electropneumatic valves 210, 220.

[0161] The operating duty cycle may be approximately 20 to 40%, such as approximately 33%, or the same duty cycle as during normal operation of the electropneumatic valves 210, 220.

[0162] Step 504 includes detecting, or if step 502 has been performed, confirming that the first electropneumatic valve 210 and / or the second electropneumatic valve 220 is malfunctioning.

[0163] Information regarding the malfunctioning electropneumatic valves 210, 220 may, in some embodiments, be output to the driver, informing him / her of the risk of the electropneumatic valves 210, 220 freezing.

[0164] The information may be output to the driver on / through an output device 410 in the cabin 101 of the vehicle 100 in the form of text, an illuminated symbol, an image, a movie, a voice message and / or a sound alone or in any combination.

[0165] In some embodiments, instructions may also be issued to the driver to perform / confirm the performance of the brake recovery function.

[0166] Step 505 includes obtaining an instruction to heat the first electropneumatic valve 210 and the second electropneumatic valve 220, ie, to begin the recovery function.

[0167] This instruction may include a driver instruction, which may include, for example, pressing a dedicated button on the vehicle's dashboard; releasing the parking brake 360; a slight nod of the head (in the case of a driver monitoring camera input to the control device 300); a hum of approval (in the case of a cabin microphone input to the control device 300), etc.

[0168] Alternatively, the instruction can be generated by an autonomous software function that simulates the human driver, or by

[0169] Step 506 includes performing a recovery function to heat the first electropneumatic valve 210 and the second electropneumatic valve 220.

[0170] In some embodiments, the recovery function may include activating an electric heating device located on the electropneumatic valves. In other embodiments, the recovery function may include providing heat via a heat exchanger or a heated liquid or heated gas line located in close proximity to the electropneumatic valves 210, 220.

[0171] In some embodiments, the recovery function may include controlling the PWM signal generator 301 of the first electropneumatic valve 210 and the second electropneumatic valve 220 to generate and provide the PWM signal with the duty cycle also for the first electropneumatic valve 210 to heat the first electropneumatic valve 210 and the second electropneumatic valve 220 to heat the valves 210, 220 with the goal of restoring the function of the electropneumatic valves 210, 220.

[0172] Step 507, which may be performed when the function of the electropneumatic valves 210, 220 is restored after performing step 506, includes controlling the PWM signal generator 301 to alternately generate and provide the PWM signal with the same or a similar duty cycle as during normal operation of the electropneumatic valves 210, 220 for the first electropneumatic valve 210 and the second electropneumatic valve 220, in order to repeatedly apply and release the parking brake 360 ​​by alternately opening and closing the first electropneumatic valve 210 and the second electropneumatic valve 220. The duty cycle may be suitable for actuating the electropneumatic valves 210, 220, ie, approximately 20 to 40%, such as approximately 33%.

[0173] The PWM signal generator 301 can be controlled to repeatedly apply and release the parking brake 360 ​​multiple times during the wet-removal function, for example, at a limited frequency. For example, the limited frequency may be 5 to 50 times in some embodiments. In some embodiments, the parking brake 360 ​​may be repeatedly applied and released during a period of time, which may be limited; for example, a limited number of seconds, such as 20 to 60 seconds.

[0174] In some embodiments, controller 300 may be capable of obtaining information about an ambient temperature. Controller 300 may then be configured to adjust the limited frequency with which PWM signal generator 301 is to repeatedly apply and release parking brake 360 ​​based on the ambient temperature.

[0175] The limited frequency with which the PWM signal generator 301 can repeatedly apply and release the parking brake 360 ​​during the wet-weather removal function may be proportional to the ambient temperature. Thus, more repetitions of applying / releasing the parking brake 360 ​​may be applied at a colder temperature, and fewer repetitions may be applied at a milder temperature.

[0176] Some examples may include setting the limited frequency to 0 when the ambient temperature exceeds zero degrees; to about 5 to 20 when the ambient temperature is around zero degrees; to about 10 to 40 when the ambient temperature is around / below -5 degrees; to about 20 to 50 when the ambient temperature is around / below -10 degrees; etc. (non-limiting examples).

[0177] Step 508, which may be performed in embodiments in which step 506 and / or step 507 have been performed, ie, the function of the electropneumatic valves 210, 220 has been restored, comprises detecting a risk of refreezing of water on the electropneumatic valves 210, 220.

[0178] A risk of water refreezing may be based on a temperature measurement of an ambient temperature compared to a threshold value.

[0179] The ambient temperature may be determined by an onboard temperature sensor. Alternatively, information about an ambient temperature may be obtained from a source external to the vehicle, such as a temperature sensor or a weather service located at the roadside or elsewhere, such as in another nearby vehicle. Such information could be obtained by the vehicle 100 via a wireless data transmission interface.

[0180] The temperature may alternatively or additionally be estimated based on a combination of knowledge of a geographical position of the vehicle 100, a planned route / destination / direction of travel of the vehicle 100 and knowledge of date / time and statistical data relating to expected temperatures with respect to the date / time at the (current or future) geographical position of the vehicle 100.

[0181] In still further embodiments, knowledge of the date / time may be used in combination with the current or future geographical position of the vehicle 100 and weather forecast data relevant to the geographical position in combination with the date / time.

[0182] Step 509, which may be performed in embodiments where step 508 has been performed, includes controlling the PWM signal generator 301 of the first electropneumatic valve 210 and the second electropneumatic valve 220 to generate and provide a PWM signal with a reduced duty cycle to the first electropneumatic valve 210 and the second electropneumatic valve 220 to heat the valves 210, 220. The reduced duty cycle is lower than required to actuate the electropneumatic valves 210, 220. This step may be referred to as a continuous heating function.

[0183] The reduced duty cycle can be set to approximately 10 to 15%, i.e., to a duty cycle that is too low to actuate the electropneumatic valves 210, 220.

[0184] Step 509 may be performed until a detection of a non-existent risk of water freezing at the electropneumatic valves 210, 220.

[0185] Some examples of the absence of these hazards may include an ambient temperature above 0 degrees Celsius and / or no moisture / water being detected inside the parking brake unit.

[0186] The above-described method steps 501 to 509 to be performed in the vehicle 100 can be implemented by the one or more control devices 300 together with a computer program product for performing at least some of the functions of method steps 501 to 509. In this way, a computer program product having instructions for performing method steps 501 to 509 in the control device 300 can perform the method 500 for heating the electropneumatic valves 210, 220 with the aim of providing heat to the electropneumatic valves 210, 220 and removing water therefrom when the computer program is loaded into the control device 300.

[0187] The above-mentioned computer program product may, for example, be provided in the form of a computer-readable medium or a data carrier carrying computer program code for performing at least some of the method steps 501 to 509 when loaded into the control device 300. The computer-readable medium may be a non-transitory, computer-readable medium such as a physical, electronic, magnetic, optical, infrared, electromagnetic, and / or semiconductor system, device, and / or apparatus.

[0188] The terminology used in the description of the embodiments as illustrated in the accompanying drawings is not intended to be limiting of the described electronically controlled pneumatic parking brake system 305, the method 500, the computer program product, the computer-readable storage medium, and / or the vehicle 100. Various features used in the various Fig. 1 to 5 and / or described in different sections of the description can be combined with each other in various embodiments with some advantage.

[0189] Various changes, substitutions and / or modifications may be made without departing from the embodiments of the invention as defined in the appended claims.

[0190] As used herein, the term "and / or" includes any and all combinations of one or more of the related listed elements. As used herein, the term "or" is to be construed as a mathematical OR, i.e., an inclusive disjunction; not as a mathematical exclusive OR (XOR), unless expressly stated otherwise. Furthermore, the singular forms "a," "an," and "the" are to be construed as "at least one," thus potentially including a plurality of entities of the same kind, unless expressly stated otherwise.It is further understood that the terms "comprises," "comprises," "comprising," and / or "having" specify the presence of recited features, acts, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, acts, integers, steps, operations, elements, components, and / or groups thereof. A single unit, such as a processor, may perform the functions of multiple elements recited in the claims. The mere fact that certain measures are recited in different dependent claims does not mean that a combination of those measures cannot be advantageously employed.A computer program may be stored / distributed on any suitable medium, for example an optical storage medium or a semiconductor medium provided with or as part of other hardware, but may also be distributed in other forms, for example via the Internet or any other wired or wireless data transmission system.

Claims

[1] An electronically controlled pneumatic parking brake system (305) for a vehicle (100), the system (305) comprising: a control device (300) configured to generate an electronic brake application signal when it receives an indication that a parking brake (360) is to be applied / activated; and to generate an electronic brake release signal when it receives an indication that the parking brake (360) is to be released / deactivated; an air supply source (230) for supplying compressed air; a first electropneumatic valve (210) connected to the control device (300) for data transmission and connected to the air supply source (230) and to a control chamber (260), the first electropneumatic valve (210) being capable of releasing the parking brake (360) by opening the first electropneumatic valve (210), thereby allowing compressed air to flow through the first electropneumatic valve (210) into the control chamber (260) when the electronic brake release signal is received from the control device (300); a second electropneumatic valve (220) connected to the control device (300) for data transmission and connected to the control chamber (260) and to an outlet opening (250), the second electropneumatic valve (220) being capable of activating the parking brake (360) by opening the second electropneumatic valve (220), thereby venting compressed air from the control chamber (260) to the atmosphere via an outlet opening (250) when the electronic brake actuation signal is received from the control device (300); wherein the control device (300) is designed to be a Detecting that the first electropneumatic valve (210) and / or the second electropneumatic valve (220) has / have a malfunction; Obtaining an instruction to heat the first electropneumatic valve (210) and the second electropneumatic valve (220); Performing a recovery function to heat the first electropneumatic valve (210) and the second electropneumatic valve (220); and when the function of the electropneumatic valves (210, 220) is restored: Controlling a pulse width modulation, "PWM" signal generator (301) to alternately generate and provide a PWM signal having an operating duty cycle to the first electropneumatic valve (210) and the second electropneumatic valve (220) to repeatedly apply and release the parking brake (360) by alternately opening and closing the first electropneumatic valve (210) and the second electropneumatic valve (220). [2] The system (305) of claim 1, wherein the recovery function for heating the electropneumatic valves (210, 220) comprises controlling the PWM signal generator (301) to generate and provide the PWM signal with the same or a similar duty cycle for the first electropneumatic valve (210) and the second electropneumatic valve (220) to heat the valves (210, 220) to thereby restore the function of the electropneumatic valves (210, 220); wherein the duty cycle is suitable for actuating the electropneumatic valves (210, 220). [3] System (305) according to one of the preceding claims, wherein the control device (300) is designed to control the PWM signal generator (301) such that the parking brake (360) is repeatedly applied and released several times. [4] The system (305) of any preceding claim, wherein the controller (300) is capable of obtaining information about an ambient temperature, and wherein the controller (300) is configured to adjust the frequency with which the PWM signal generator (301) is to repeatedly apply and release the parking brake (360) based on the ambient temperature. [5] System (305) according to any one of claims 2 to 4, wherein the control device (300) is designed to be a Detecting a risk of water freezing at the electropneumatic valves (210, 220); Detecting that the first electropneumatic valve (210) and / or the second electropneumatic valve (220) has / have a malfunction when it is detected that the ignition is switched on when the vehicle (100) is stationary and the parking brake (360) is applied; and Controlling the PWM signal generator (301) to generate and provide a PWM signal having an operating duty cycle for the second electropneumatic valve (220) to heat the second electropneumatic valve (220) with the aim of restoring the function of the second electropneumatic valve (220); wherein the operating duty cycle is suitable for actuating the electropneumatic valves (210, 220). [6] System (305) according to any one of the preceding claims, wherein the control device (300) is configured to control the PWM signal generator (301) to generate and provide the PWM signal with the same duty cycle as in normal operation. [7] The system (305) of any preceding claim, wherein the duty cycle is about 20 to 40%. [8] The system (305) of any preceding claim, wherein the controller (300) is capable of obtaining information about an ambient temperature, and wherein the controller (300) is configured to control the PWM signal generator (301) to generate and provide the PWM signal for a time-limit period, the time-limit period being adjusted based on the ambient temperature. [9] System (305) according to any one of the preceding claims, wherein the control device (300) is capable of Detecting a risk of refreezing of water at the electropneumatic valves (210, 220); and Controlling the PWM signal generator (301) of the first electropneumatic valve (210) and the second electropneumatic valve (220) to generate and provide a PWM signal with a reduced duty cycle for the first electropneumatic valve (210) and the second electropneumatic valve (220) to heat the valves (210, 220), the reduced duty cycle being lower than required to actuate the electropneumatic valves (210, 220). [10] The system (305) of claim 9, wherein the control device (300) is capable of detecting the risk of water freezing on the electropneumatic valves (210, 220) based on a comparison between an ambient temperature and a temperature threshold. [11] The system (305) of any one of claims 9 to 10, wherein the reduced duty cycle is about 10 to 15%. [12] A method (500) for a control device (300) of a vehicle (100) having an electronically controlled pneumatic parking brake system (305) according to any one of claims 1 to 11, the method (500) comprising the steps of: Detecting (504) that the first electropneumatic valve (210) and / or the second electropneumatic valve (220) has / have a malfunction; Obtaining (505) an instruction to heat the first electropneumatic valve (210) and the second electropneumatic valve (220); Performing (506) a recovery function to heat the first electropneumatic valve (210) and the second electropneumatic valve (220); and when the function of the electropneumatic valves (210, 220) is restored: Controlling (507) a pulse width modulation, "PWM" signal generator (301) to alternately generate and provide a PWM signal having an operating duty cycle for the first electropneumatic valve (210) and the second electropneumatic valve (220), the operating duty cycle being suitable for actuating the electropneumatic valves (210, 220) to repeatedly apply and release the parking brake (360) by alternately opening and closing the first electropneumatic valve (210) and the second electropneumatic valve (220). [13] The method (500) of claim 12, wherein the restoring function for heating the electropneumatic valves (210, 220) comprises controlling the PWM signal generator (301) to generate and provide the PWM signal with the same or a similar duty cycle for the first electropneumatic valve (210) and the second electropneumatic valve (220) to heat the valves (210, 220) to thereby restore the function of the electropneumatic valves (210, 220); wherein the duty cycle is suitable for actuating the electropneumatic valves (210, 220). [14] The method (500) of any one of claims 12 to 13, wherein the method (500) further comprises the steps of: Detecting (501) a risk of water freezing at the electropneumatic valves (210, 220); Detecting (502) that the first electropneumatic valve (210) and / or the second electropneumatic valve (220) has / have a malfunction when it is detected that the ignition is switched on when the vehicle (100) is stationary and the parking brake (360) is applied; and Controlling (503) the PWM signal generator (301) such that it generates and provides the PWM signal with the duty cycle for the second electropneumatic valve (220) to heat the second electropneumatic valve (220) with the aim of restoring the function of the second electropneumatic valve (220), wherein the duty cycle is suitable for actuating the electropneumatic valves (210, 220). [15] Method (500) according to any one of claims 12 to 14, wherein the method (500) comprises a series of steps to be performed when the function of the electropneumatic valves (210, 220) is restored: Detecting (508) a risk of water refreezing at the electropneumatic valves (210, 220); and Controlling (509) the PWM signal generator (301) of the first electropneumatic valve (210) and the second electropneumatic valve (220) to generate and provide the PWM signal with a reduced duty cycle for the first electropneumatic valve (210) and the second electropneumatic valve (220) to heat the valves (210, 220), wherein the reduced duty cycle is lower than required to actuate the electropneumatic valves (210, 220). [16] A computer program product comprising instructions which, when executed by a computer, cause the computer to perform the steps of the method (500) of any of claims 12 to 14. [17] A computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to perform the steps of the method (500) of any of claims 12 to 14. [18] A vehicle (100) having an electronically controlled pneumatic parking brake system (305) according to any one of claims 1 to 11.

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