SE546583C2

SE546583C2 - Method of Controlling Operation of a Pneumatic Parking Brake System, Computer Program, Computer-Readable Medium, Control arrangement, Pneumatic parking brake System, and Vehicle

Info

Publication number: SE546583C2
Application number: SE2350478A
Authority: SE
Inventors: Johan Thorsell; Petter Tuvehed; Xavier Dreux
Original assignee: Scania Cv Ab
Priority date: 2023-04-21
Filing date: 2023-04-21
Publication date: 2024-12-10
Also published as: DE102024109422A1; SE2350478A1

Abstract

A method (100) of controlling operation of a pneumatic parking brake system (1) of a vehicle (2) is disclosed, the pneumatic parking brake system (1) comprising a first supply conduit (d) and a first valve (v1) connected to the first supply conduit (d). The method (100) comprises the steps of determining (110), based on a weight estimate of the vehicle (2) and a magnitude of a requested retardation, a first desired pressure level supplied to the first wheel brake arrangement (b1), determining (120), based on the first desired pressure level and a current pressure in the first supply conduit (d), a first opening time duration of the first valve (v1) required for reaching the first desired pressure level, and controlling (130) the first valve (v1) to assume an open state during a first time period having the first opening time duration. The present disclosure further relates to a computer program, a computer-readable medium (200), a control arrangement (21), a pneumatic parking brake system (1), and a vehicle (2).

Description

TECHNICAL FIELD The present disclosure relates to a method of controlling operation of a pneumatic parking brake system of a vehicle. The present disclosure further relates to a computer program, a computer-readable medium, a control arrangement for controlling operation of a pneumatic parking brake system of a vehicle, a pneumatic parking brake system for a vehicle, and a vehicle comprising a pneumatic parking brake system.

BACKGROUND Parking brake systems are used on motor vehicles to keep the vehicle securely motionless when parked. Usually, a parking brake system can be controlled via an actuator arranged in a driver environment of the vehicle, such as a parking brake lever, a push button, or the like. l\/loreover, motor vehicles comprise a service brake arrangement controllable to brake the vehicle during movement thereof. The typical service brake arrangement comprises at least two service brake circuits, one for one for a number of wheels arranged at a front axle of the vehicle and one for a number of wheels arranged at a rear axle of the vehicle.

A parking brake system may comprise a plurality of circuits being separate from circuits of the service brake arrangement. The plurality of circuits of the parking brake system may comprise a front circuit associated with the front axle and a rear circuit associated with the rear axle. l\/lany vehicles, such as heavy road vehicles, comprise pneumatic brake systems. A pneumatic parking brake system normally comprise a pre-stressed spring in a spring brake chamber. When the spring is compressed no brake force is applied on the wheels and when the pressure decreases and the spring is decompressed, brake force is applied on the wheels. The brake force of the parking brake thus increases when the pressure in the respective spring brake chamber decreases. ln this manner, pneumatic circuits of the pneumatic parking brake system do not need to be pressurized during long periods of time and it can be ensured that the vehicle remains securely motionless when parked even in case of a leakage in the pneumatic parking brake system.Both safety concerns and legal requirements require redundant braking systems of vehicles which are capable of braking the vehicle also in case of failures, such as failure in electronic control of a service brake arrangement, loss in pressure control of a circuit of the service brake arrangement, or the like. Some systems utilize a pneumatic parking brake system in emergency situations. ln this manner, the vehicle can be retarded also in case of a loss in pressure control of one or more circuits of the service brake arrangement.

However, the use of pneumatic parking brake systems in emergency situations is associated with some problems and drawbacks. One problem is that pneumatic parking brake systems of vehicles are not normally designed to be able to quickly retard the vehicle. Another problem is that it may be difficult to provide an accurate control of the retardation power when using a pneumatic parking brake system for retarding the vehicle. Still another problem is that it may be difficult to provide braking stability of the vehicle when using a pneumatic parking brake system for retarding the vehicle.

Furthermore, generally, it is an advantage if products, such as vehicles and associated components, systems, and arrangements, comprise some features and functions while having conditions and/or characteristics suitable for being manufactured and assembled in a cost-efficient manner.

SUMMARY lt is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a first aspect of the invention, the object is achieved by a method of controlling operation of a pneumatic parking brake system of a vehicle, the method being performed by a control arrangement and the pneumatic parking brake system comprising an air supply system, a first supply conduit connecting the air supply system to a first wheel brake arrangement of the vehicle, wherein the first wheel brake arrangement is configured to brake a number of wheels at a first wheel axle of the vehicle, and a first valve controllable to an open state in which the first valve releases air from the first supply conduit. The method comprises the steps of: - obtaining a weight estimate of the vehicle, - obtaining a current pressure in the first supply conduit, and upon receipt of a request for retardation of the vehicle by use of the pneumatic parking brake system during movement of the vehicle,- determining, based on the weight estimate of the vehicle and a magnitude of the requested retardation, a first desired pressure level supplied to the first wheel brake arrangement, - determining, based on the first desired pressure level and the obtained current pressure in the first supply conduit, a first opening time duration of the first valve required for reaching the first desired pressure level, and - controlling the first valve to assume the open state during a first time period having the first opening time duration. ln this manner, a method is provided having conditions for quickly applying a braking torque onto the number of wheels at the first wheel axle of the vehicle using the pneumatic parking brake system. I\/|oreover, a method is provided having conditions for an accurate control of the braking power provided by the first wheel brake arrangement, and thus also conditions for an accurate control of the retardation power applied to the vehicle, using the pneumatic parking brake system. As a further result, a method is provided capable of reducing a stopping distance of the vehicle when retarding the vehicle by use of the pneumatic parking brake system. Accordingly, due to these features, a method is provided capable of increasing the operational safety of the vehicle.

The method has conditions for quickly applying a braking torque onto the number of wheels because the pneumatic parking brake system comprises the first valve and because the method comprises the step of controlling the first valve to assume the open state during a first time period having the first opening time duration.

Moreover, the method has conditions for an accurate control of the braking power provided by the first wheel brake arrangement because the method comprises the steps of obtaining the weight estimate of the vehicle, obtaining the current pressure in the first supply conduit, and because the first desired pressure level is determined based on the weight estimate of the vehicle and a magnitude of the requested retardation. Furthermore, the method has conditions for an accurate control of the braking power provided by the first wheel brake arrangement because the first opening time duration of the first valve required for reaching the first desired pressure level is determined based on the first desired pressure level and the obtained current pressure in the first supply conduit.

I\/|oreover, a method is provided capable of increasing the operational safety of a vehicle without significantly adding costs and complexity to the vehicle. This is because the method may only require the addition of a first valve connected to the first supply conduit and acontrol arrangement for providing the quick and accurate control of the braking torque applied to the number of wheels arranged at the first wheel axle of the vehicle.

Accordingly, a method is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

The request for retardation of the vehicle by use of the pneumatic parking brake system during movement of the vehicle may be received from another device, system, or unit for example in case of a detection of a malfunction of a service brake arrangement of the vehicle. The request for retardation of the vehicle may comprise desired magnitude of the requested retardation of the vehicle. The device, system, or unit may generate the request when it is determined that the vehicle is to be braked and a malfunction of the service brake arrangement of the vehicle is detected. The request may be received in the control arrangement. ln other words, according to embodiments herein, at least part of the method may be performed in case of a detection of a malfunction of a service brake arrangement of the vehicle and/or a malfunction of a device or system for controlling the service brake arrangement.

The device, system, or unit referred to above may form at least part of an autonomous driving system of the vehicle, wherein the autonomous driving system is configured to drive, i.e., steer, brake, and/or propel, the vehicle based on input from a number of sensor devices. The autonomous driving system may be configured to drive the vehicle in an at least partially autonomous manner, i.e., drive the vehicle at least in part in a manner not requiring the direct intervention of a human. ln other words, the method according to the present disclosure can provide braking redundancy of a vehicle having autonomous driving capabilities. That is, due to the features of the method, braking redundancy can be provided to vehicles having autonomous driving capabilities to ensure that the vehicle can be braked in a quick and accurate manner also in case of malfunctions of a service brake arrangement of the vehicle, and/or in case of malfunctions of the autonomous driving system, such as for example in case of a failure in electronic control of a service brake arrangement, loss in pressure control of a circuit of the service brake arrangement, and the like.

The weight estimate of the vehicle may be represented by a current weight estimate of the vehicle. The weight estimate of the vehicle may be obtained by estimating a current weight of the vehicle. According to such embodiments, the current weight of the vehicle may be estimated based on at least one of torque and/or power data from a power source of thevehicle, current inclination data of the vehicle and/or of a surface currently supporting the vehicle, current speed of the vehicle, a current rate of change of the speed of the vehicle, and the like.

The current pressure in the first supply conduit may be obtained using one or more sensor devices configured to provide data representative of the current pressure in the first supply conduit. As an alternative, or in addition, the current pressure in the first supply conduit may be obtained by inputting a current set pressure of the first supply conduit.

The feature that first valve is controlled to assume the open state during the first time period having the first opening time duration means that the first valve is controlled to assume the open state during a first time period having a duration corresponding to the first opening time duration.

The first wheel axle, as referred to herein, may be a front wheel axle or a rear wheel axle of the vehicle. ln other words, the first wheel brake arrangement, as referred to herein, may be configured to brake a number of wheels at a front wheel axle or a rear wheel axle of the vehicle. Furthermore, according to some embodiments, the vehicle may comprise two front wheel axles. According to such embodiments, the first wheel axle, as referred to herein, may be one of such two front wheel axles. ln other words, the first wheel brake arrangement, as referred to herein, may be configured to brake a number of wheels at one of such two front wheel axles.

Optionally, the step of determining the first desired pressure level comprises: - determining the first desired pressure level based on at least one of a configuration of the vehicle and a configuration of the first wheel brake arrangement.

Thereby, it can be further ensured that the braking torque can be applied onto the number of wheels at the first wheel axle of the vehicle in a quick and accurate manner. This is because conditions are provided for an adaptation of the first desired pressure level based on at least one of a configuration of the vehicle and a configuration of the first wheel brake arrangement. Moreover, due to these features, a short stopping distance of the vehicle can be ensured.

Optionally, the step of determining the first opening time duration comprises: - determining the first opening time duration based on at least one of a configuration of the first valve and configuration of the first supply conduit.Thereby, it can be further ensured that the braking torque can be applied onto the number of wheels at the first wheel axle of the vehicle in a quick and accurate manner. This is because conditions are provided for an adaptation of the first opening time duration based on at least one of a configuration of the first valve and configuration of the first supply conduit. I\/|oreover, due to these features, a short stopping distance of the vehicle can be ensured.

Optionally, the pneumatic parking brake system further comprises a second supply conduit connecting the air supply system to a second wheel brake arrangement of the vehicle, wherein the second wheel brake arrangement is configured to brake a number of wheels at a second wheel axle of the vehicle, and a second valve controllable to an open state in which the second valve releases air from the second supply conduit, and wherein the method comprises the steps of: - obtaining a current pressure in the second supply conduit, and upon receipt of the request for retardation of the vehicle by use of the pneumatic parking brake system during movement of the vehicle: - determining, based on the weight estimate of the vehicle and a magnitude of the requested retardation, a second desired pressure level supplied to the second wheel brake arrangement, - determining, based on the second desired pressure level and the obtained current pressure in the second supply conduit, a second opening time duration of the second valve required for reaching the second desired pressure level, and - controlling the second valve to assume the open state during a second time period having the second opening time duration. ln this manner, a method is provided having conditions for quickly applying a braking torque onto the number of wheels at the second wheel axle of the vehicle. I\/|oreover, a method is provided having conditions for an accurate control of the braking power provided by the second wheel brake arrangement, and thus also conditions for an accurate control of the retardation power applied to the vehicle. I\/|oreover, since a quick and accurate control can be provided of each of the first and second wheel brake arrangements, conditions are provided for an increased braking stability of the vehicle. As a further result, a method is provided capable of further increasing the operational safety of the vehicle.

According to some embodiments, the first wheel axle represents a front wheel axle of the vehicle and the second wheel axle represents a rear wheel axle of the vehicle. ln other words, according to such embodiments, the first wheel brake arrangement is configured tobrake a number of front wheels of the vehicle whereas the second wheel brake arrangement is configured to brake a number of rear wheels of the vehicle.

According to further embodiments, each of the first and second wheel axles may represent a front wheel axle or a rear wheel axle. ln other words, according to such embodiments, each of the first and second wheel brake arrangements may be configured to brake a number of front wheels or a number of rear wheels of the vehicle.

The feature that second valve is controlled to assume the open state during the second time period having the second opening time duration means that the second valve is controlled to assume the open state during a second time period having a duration corresponding to the second opening time duration.

Optionally, the step of controlling the first valve and the step of controlling the second valve are performed such that the first and second valves are controlled to the respective open state at least substantially simultaneously.

Thereby, it can be further ensured that the vehicle is braked in a quick and accurate manner providing a high degree of braking stability.

Optionally, the second desired pressure level is different from the first desired pressure level. Thereby, it can be further ensured that a high degree of braking stability can be provided.

Optionally, the second opening time duration is different from the first opening time duration. Thereby, it can be further ensured that a high degree of braking stability can be provided.

Optionally, the step of determining the first desired pressure level and the step of determining the second desired pressure level are performed such that a difference between the first and second desired pressure levels increases with increased magnitudes of the requested retardation.

Thereby, it can be further ensured that a high degree of braking stability can be provided in various driving situations of the vehicle.

Optionally, the first wheel axle is a front wheel axle of the vehicle and the second wheel axle is a rear wheel axle of the vehicle, and wherein the step of determining the first desired pressure level and the step of determining the second desired pressure level are performedsuch that the second desired pressure level is set to a higher pressure level than the first desired pressure level when the magnitude of the requested retardation exceeds a threshold magnitude. ln this manner, it can be ensured that the first wheel brake arrangement provides greater braking power than the second wheel brake arrangement in situations in which the magnitude of the requested retardation exceeds the threshold magnitude. ln other words, it can be ensured that a higher braking power is applied to the number of wheels at the front wheel axle of the vehicle than what is applied onto the number of wheels at the rear wheel axle of the vehicle when the magnitude of the requested retardation exceeds the threshold magnitude. Thereby, it can be further ensured that a high degree of braking stability is provided in various driving situations of the vehicle. l\/loreover, due to these features, a short stopping distance of the vehicle can be ensured.

According to a second aspect of the invention, the object is achieved by a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to some embodiments of the present disclosure. Since the computer program comprises instructions which, when the program is executed by a computer, cause the computer to carry out the method according to some embodiments described herein, a computer program is provided which provides conditions for overcoming, or at least alleviating, at least some of the above-mentioned drawbacks. As a result, the above-mentioned object is achieved.

According to a third aspect of the invention, the object is achieved by a computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to some embodiments of the present disclosure. Since the computer-readable medium comprises instructions which, when the program is executed by a computer, cause the computer to carry out the method according to some embodiments described herein, a computer-readable medium is provided which provides conditions for overcoming, or at least alleviating, at least some of the above-mentioned drawbacks. As a result, the above-mentioned object is achieved.

According to a fourth aspect of the invention, the object is achieved by a control arrangement for controlling operation of a pneumatic parking brake system of a vehicle, the pneumatic parking brake system comprising an air supply system, a first supply conduit connecting the air supply system to a first wheel brake arrangement of the vehicle, wherein the first wheel brake arrangement is configured to brake a number of wheels at a first wheel axle of thevehicle, and a first valve controllable to an open state in which the first valve releases air from the first supply conduit. The control arrangement is configured to: - obtain a weight estimate of the vehicle, - obtain a current pressure in the first supply conduit, and upon receipt of a request for retardation of the vehicle by use of the parking brake system during movement of the vehicle: - determine, based on the weight estimate of the vehicle and a magnitude of the requested retardation, a first desired pressure level supplied to the first wheel brake arrangement, - determine, based on the first desired pressure level and the obtained current pressure in the first supply conduit, a first opening time duration of the first valve required for reaching the first desired pressure level, and - control the first valve to assume the open state during a first time period having the first opening time duration. ln this manner, a control arrangement is provided having conditions for quickly causing a braking torque to be applied onto the number of wheels at the first wheel axle of the vehicle using the pneumatic parking brake system. l\/loreover, a control arrangement is provided having conditions for an accurate control of the braking power provided by the first wheel brake arrangement, and thus also conditions for an accurate control of the retardation power applied to the vehicle, using the pneumatic parking brake system. As a further result, a control arrangement is provided capable of reducing a stopping distance of the vehicle when retarding the vehicle by use of the pneumatic parking brake system. Accordingly, due to these features, a control arrangement is provided capable of increasing the operational safety of the vehicle.

The control arrangement has conditions for quickly applying a braking torque onto the number of wheels because the pneumatic parking brake system comprises the first valve and because the control arrangement is configured to control the first valve to assume the open state during a first time period having the first opening time duration. l\/loreover, the control arrangement has conditions for an accurate control of the braking power provided by the first wheel brake arrangement because the control arrangement is configured to obtain the weight estimate of the vehicle, obtain the current pressure in the first supply conduit, and because the first desired pressure level is determined by the control arrangement based on the weight estimate of the vehicle and a magnitude of the requested retardation. Furthermore, the control arrangement has conditions for an accurate control of the braking power provided by the first wheel brake arrangement because the first opening time duration of the first valve required for reaching the first desired pressure level is determined by the control arrangement based on the first desired pressure level and the obtained current pressure in the first supply conduit.

Moreover, a control arrangement is provided capable of increasing the operational safety of a vehicle without significantly adding costs and complexity to the vehicle. This is because the control arrangement may only require the addition of a first valve connected to the first supply conduit for providing the quick and accurate control of the braking torque applied to the number of wheels arranged at the first wheel axle of the vehicle.

Accordingly, a control arrangement is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved. lt will be appreciated that the various embodiments described for the method are all combinable with the control arrangement as described herein. That is, the control arrangement according to the fourth aspect of the invention may be configured to perform any one of the method steps of the method according to the first aspect of the invention.

According to a fifth aspect of the invention, the object is achieved by a pneumatic parking brake system for a vehicle, the pneumatic parking brake system comprising an air supply system, a first supply conduit connecting the air supply system to a first wheel brake arrangement of the vehicle, wherein the first wheel brake arrangement is configured to brake a number of wheels at a first wheel axle of the vehicle, a first valve controllable to an open state in which the first valve releases air from the first supply conduit, and a control arrangement, wherein the control arrangement is configured to: - obtain a weight estimate of the vehicle, - obtain a current pressure in the first supply conduit, and upon receipt of a request for retardation of the vehicle by use of the parking brake system during movement of the vehicle: - determine, based on the weight estimate of the vehicle and a magnitude of the requested retardation, a first desired pressure level supplied to the first wheel brake arrangement, - determine, based on the first desired pressure level and the obtained current pressure in the first supply conduit, a first opening time duration of the first valve required for reaching the first desired pressure level, and- control the first valve to assume the open state during a first time period having the first opening time duration.

Thereby, a pneumatic parking brake system is provided having conditions for quickly applying a braking torque onto the number of wheels at the first wheel axle of the vehicle. Moreover, a pneumatic parking brake system is provided having conditions for an accurate control of the braking power provided by the first wheel brake arrangement, and thus also conditions for an accurate control of the retardation power applied to the vehicle. As a further result, a pneumatic parking brake system is provided capable of reducing a stopping distance of the vehicle. Accordingly, due to these features, a pneumatic parking brake system is provided capable of increasing the operational safety of the vehicle.

Moreover, a pneumatic parking brake system is provided capable of increasing the operational safety of a vehicle without significantly adding costs and complexity to the vehicle. This is because the pneumatic parking brake system may only require the addition of a first valve connected to the first supply conduit and the control arrangement for providing the quick and accurate control of the braking torque applied to the number of wheels arranged at the first wheel axle of the vehicle.

Accordingly, a pneumatic parking brake system is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

According to a sixth aspect of the invention, the object is achieved by a vehicle comprising a first wheel axle, a number of wheels arranged at the first wheel axle, a first wheel brake arrangement configured to brake the number of wheels, and a pneumatic parking brake system according to some embodiments of the present disclosure.

Since the vehicle comprises a pneumatic parking brake system according to some embodiments, a vehicle is provided having conditions for quickly causing a braking torque to be applied onto the number of wheels at the first wheel axle of the vehicle using the pneumatic parking brake system. Moreover, a vehicle is provided having conditions for an accurate control of the braking power provided by the first wheel brake arrangement, and thus also conditions for an accurate control of the retardation power applied to the vehicle, using the pneumatic parking brake system. As a further result, a vehicle is provided capable of obtaining a reducing a stopping distance when the vehicle is retarded by use of thepneumatic parking brake system. Accordingly, due to these features, an increased operational safety of the vehicle can be provided.

Moreover, the operational safety of a vehicle can be increased without significantly adding costs and complexity to the vehicle. This is because the vehicle may only require the addition of a first valve connected to the first supply conduit for providing the quick and accurate control of the braking torque applied to the number of wheels arranged at the first wheel axle of the vehicle.

Optionally, the vehicle is a heavy road vehicle, such as a truck or a bus. Thereby, a heavy road vehicle is provided having at least some of the above-mentioned advantages.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which: Fig. 1 schematically illustrates a vehicle according to some embodiments, Fig. 2 schematically illustrates a pneumatic parking brake system of the vehicle illustrated in Fig. 1, Fig. 3 schematically illustrates a method of controlling operation of a pneumatic parking brake system of a vehicle, and Fig. 4 illustrates a computer-readable medium.

DETAILED DESCRIPTION Aspects of the present invention will now be described more fully. Like reference signs refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 schematically illustrates a vehicle 2 according to some embodiments. According to the illustrated embodiments, the vehicle 2 is a truck, i.e., a type of heavy road vehicle as well as a type of heavy commercial vehicle. According to further embodiments, the vehicle 2, as referred to herein, may be another type of heavy or lighter type of manned or unmannedvehicle for land-based propulsion such as a lorry, a bus, a construction vehicle, a tractor, a car, or the like.

The vehicle 2 comprises a powertrain 20. The powertrain 20 comprises a transmission 14 and a power source 3. The power source 3 is configured to provide motive power to the vehicle 2 via the transmission 14. ln more detail, the transmission 14 is configured to transmit power between the power source 3 and wheels w2, w3 of the vehicle 2. The transmission 14 is comprised in a drivetrain of the vehicle 2, wherein the drivetrain can be said to comprise all components that transmit power from the power source 3 to wheels w2, w3 of the vehicle 2, such as the transmission 14, driveshafts, differentials, axles, and the like.

The power source 3 of the vehicle 2 may comprise an internal combustion engine. As an alternative, or in addition, the power source 3 may comprise one or more electric machines. ln other words, the powertrain 20 may comprise one or more electric machines in addition to an internal combustion engine for providing motive power to the vehicle 2. Thus, the powertrain 20 of the vehicle 2 may be a so-called hybrid electric powertrain. According to further embodiments, the vehicle 2 may comprise a fully electric powertrain comprising one or more electric machines as the only means for providing motive power to the vehicle ln Fig. 1, the vehicle 2 is illustrated as positioned in an intended use position on a surface 51 supporting the vehicle 2. As seen in Fig. 1, the vehicle 2 comprises a number of wheels w1, w2, w3 configured to abut against the surface 51 when the vehicle 2 is positioned in the intended use position thereon. l\/loreover, in Fig. 1, a forward moving direction fd and a reverse moving direction rd are indicated. The reverse moving direction rd of the vehicle 2 is opposite to the forward moving direction fd of the vehicle ln Fig. 1, the vehicle 2 is illustrated as comprising three wheel axles, namely a first wheel axle a1, a second wheel axle a2, and a third wheel axle a3. According to further embodiments, the vehicle 2 may comprise another number of wheel axles a1, a2, a3, such as two wheel axles only or more than three wheel axles. As is further explained herein, each wheel axle a1, a2, a3 of the vehicle 2 comprises a number of wheels w1, w2, w3. The number of wheels w1, w2, w3 of the vehicle 2 may also be referred to as a number of ground engaging wheels w1, w2, w According to the illustrated embodiments, the first wheel axle a1 constitutes a front wheel axle and the wheels w1 thereof thus constitute front wheels of the vehicle 2. l\/loreover, according to the illustrated embodiments, each of the second and third wheel axle a2, aconstitutes a rear wheel axle and the wheels w2, w3 thereof constitute rear wheels of the vehicle 2. Moreover, according to the illustrated embodiments, the wheels W1 of the first wheel axle a1 are steered non-driven wheels whereas the wheels w2, w3 of the second and third wheel axle a2, a3 are non-steered driven wheels. However, according to further embodiments, the vehicle 2 may comprise another configuration of wheels w1, w2, w3 and wheel axles a1, a2, a3 than depicted in Fig.

Fig. 2 schematically illustrates a pneumatic parking brake system 1 of the vehicle 2 illustrated in Fig. 1. Moreover, in Fig. 2, the first, second, and third wheels axles a1, a2, a3 and the wheels w1, w2, w3 thereof are schematically illustrated. As can be seen in Fig. 2, according to the illustrated embodiments, each of the second and third wheel axles a2, a3 comprises four wheels w2, w3 whereas the first wheel axle a1 comprises tvvo wheels W1 only. According to further embodiments, each wheel axle a1, a2, a3 of the vehicle 2 may comprise another number of wheels w1, w2, w3. Below, simultaneous reference is made to Fig. 1 and Fig. 2, if not indicated othen/vise.

The vehicle 2 comprises a first wheel brake arrangement b1. The first wheel brake arrangement b1 is configured to brake the number of wheels W1 of the first wheel axle a1, i.e., is configured to brake the number of wheels W1 arranged at the first wheel axle a1. Moreover, according to the illustrated embodiments, the vehicle 2 comprises a second wheel brake arrangement b2. The second wheel brake arrangement b2 is configured to brake the number of wheels W2 of the second wheel axle a2, i.e., is configured to brake the number of wheels W2 arranged at the second wheel axle a2. Likewise, according to the illustrated embodiments, the vehicle 2 comprises a third wheel brake arrangement b3. The third wheel brake arrangement b3 is configured to brake the number of wheels w3 of the third wheel axle a3, i.e., is configured to brake the number of wheels w3 arranged at the third wheel axle a Each of the first, second, and third wheel brake arrangement b1, b2, b3 may comprise a number of friction brakes such as a number of drum brakes and/or disc brakes. Drum brakes normally comprise a cylinder-shaped part called a brake drum and a set of shoes or pads controllable to be pressed against the cylinder-shaped part to create friction therebetween for braking the wheels w1, w2, w3. Disc brakes normally comprise a disc and a set of pads controllable to be pressed against the disc to create friction therebetween for braking the wheels w1, w2, w The vehicle 2 further comprises a service brake arrangement. The service brake arrangement is not depicted in Fig. 1 or Fig. 2 for reasons of brevity and clarity. The service brake arrangement may be configured to control operation of the first, second, and third wheel brake arrangement b1, b2, b3 to retard/brake the vehicle 2 during normal driving thereof. The service brake arrangement may be configured to control operation of the first, second, and third wheel brake arrangement b1, b2, b3 by controlling a pneumatic pressure supplied to the respective first, second, and third wheel brake arrangement b1, b2, b The pneumatic parking brake system 1 comprises an air supply system 10. The air supply system 10 may comprise a pressure reservoir, an air compressor configured to compress air from the surrounding to the pressure reservoir, a number of control valves, and the like. According to the illustrated embodiments, the air supply system 10 of the pneumatic parking brake system 1 is separate from an air supply system of the service brake arrangement of the vehicle The pneumatic parking brake system 1 further comprises a first supply conduit c1 connecting the air supply system 10 to the first wheel brake arrangement b1 of the vehicle 2. l\/loreover, according to the illustrated embodiments, the pneumatic parking brake system 1 comprises a second supply conduit c2 connecting the air supply system 10 to the second wheel brake arrangement b2 of the vehicle 2. Likewise, according to the illustrated embodiments, the pneumatic parking brake system 1 comprises a third supply conduit c3 connecting the air supply system 10 to the third wheel brake arrangement b3 of the vehicle 2. According to the illustrated embodiments, each of the first, second, and third supply conduits c1, c2, c3 is separate from the other of the first, second, and third supply conduits c1, c2, c3. Moreover, according to the illustrated embodiments, each of the first, second, and third supply conduits c1, c2, c3 is separate from supply conduits of the service brake arrangement of the vehicle 2. Each of the first, second, and third supply conduits c1, c2, c3 may also be referred to as a respective first, second, and third pneumatic conduit.

The pneumatic parking brake system 1 further comprises a first valve v1 controllable to an open state in which the first valve v1 releases air from the first supply conduit c1. The feature that the first valve v1 releases air from the first supply conduit c1 when the first valve v1 is in the open state means that the first valve v1 reduces the pneumatic pressure in the first supply conduit c1 by venting air from the first supply conduit c1 when the first valve v1 is in the open state. The first valve v1 may release/vent air from the first supply conduit c1 to the surroundings and/or to a separate venting conduit, device, or unit when the first valve v1 is in the open state.Moreover, according to the illustrated embodiments, the pneumatic parking brake system 1 comprises a second valve v2 controllable to an open state in which the second valve v2 releases air from the second supply conduit c2. The feature that the second valve v2 releases air from the second supply conduit c2 when the second valve v2 is in the open state means that the second valve v2 reduces the pneumatic pressure in the second supply conduit c2 by venting air from the second supply conduit c2 when the second valve v2 is in the open state. The second valve v2 may release/vent air from the second supply conduit c2 to the surroundings and/or to a separate venting conduit, device, or unit when the second valve v2 is in the open state.

Likewise, according to the illustrated embodiments, the pneumatic parking brake system 1 comprises a third valve v3 controllable to an open state in which the third valve v3 releases air from the third supply conduit c3. The feature that the third valve v3 releases air from the third supply conduit c3 when the third valve v3 is in the open state means that the third valve v3 reduces the pneumatic pressure in the third supply conduit c3 by venting air from the third supply conduit c3 when the third valve v3 is in the open state. The third valve v3 may release/vent air from the third supply conduit c3 to the surroundings and/or to a separate venting conduit, device, or unit when the third valve v3 is in the open state.

Each of the first, second, and third valve v1, v2, v3 may also be referred to as a venting valve, a pneumatic valve, a pneumatic control valve, or the like. Moreover, as understood from the above, each of the first, second, and third valve v1, v2, v3 is fluidly connected to the respective first, second, and third supply conduit c1, c2, c As can be seen in Fig. 2, the pneumatic parking brake system 1 comprises a control arrangement 21. The control arrangement 21 is configured to control operation of the pneumatic parking brake system 1. The control arrangement 21 may be comprised in a vehicle 2 comprising the pneumatic parking brake system 1. The features, functions, and advantages of the control arrangement 21 are further explained below.

According to the illustrated embodiments, the first wheel brake arrangement b1 is configured to brake the number of wheels w1 arranged at the first wheel axle a1 when the pressure supplied to the first wheel brake arrangement b1 via the first supply conduit c1 declines below a first threshold pressure. The first wheel brake arrangement b1 may comprise a spring-loaded mechanism configured to ensure that the number of wheels w1 arranged at the first wheel axle a1 is braked when the pressure supplied to the first wheel brake arrangement b1 via the first supply conduit c1 declines below the first threshold pressure.The air supply system 10 may be configured to supply a set pressure to the first wheel brake arrangement b1, being above the first threshold pressure, via the first supply conduit c1 when no braking of the number of wheels w1 arranged at the first wheel axis a1 is requested. Moreover, the control arrangement 21 may be configured to maintain the first valve v1 in a closed state, in which no air is released/vent air from the first supply conduit c1 via the first valve v1, when no braking of the number of wheels w1 arranged at the first wheel axis a1 is requested.

Likewise, according to the illustrated embodiments, the second wheel brake arrangement b2 is configured to brake the number of wheels w2 arranged at the second wheel axle a2 when the pressure supplied to the second wheel brake arrangement b2 via the second supply conduit c2 declines below a second threshold pressure. The second wheel brake arrangement b2 may comprise a spring-loaded mechanism configured to ensure that the number of wheels w2 arranged at the second wheel axle a2 is braked when the pressure supplied to the second wheel brake arrangement b2 via the second supply conduit c2 declines below the second threshold pressure. The air supply system 10 may be configured to supply a set pressure to the second wheel brake arrangement b2, being above the second threshold pressure, via the second supply conduit c2 when no braking of the number of wheels w2 arranged at the second wheel axis a2 is requested. Moreover, the control arrangement 21 may be configured to maintain the second valve v2 in a closed state, in which no air is released/vent air from the second supply conduit c2 via the second valve v2, when no braking of the number of wheels w2 arranged at the second wheel axis a2 is requested.

Moreover, according to the illustrated embodiments, the third wheel brake arrangement b3 is configured to brake the number of wheels w3 arranged at the third wheel axle a3 when the pressure supplied to the third wheel brake arrangement b3 via the third supply conduit c3 declines below a third threshold pressure. The third wheel brake arrangement b3 may comprise a spring-loaded mechanism configured to ensure that the number of wheels w3 arranged at the third wheel axle a3 is braked when the pressure supplied to the third wheel brake arrangement b3 via the third supply conduit c3 declines below the third threshold pressure. The air supply system 10 may be configured to supply a set pressure to the third wheel brake arrangement b3, being above the third threshold pressure, via the third supply conduit c3 when no braking of the number of wheels w3 arranged at the third wheel axis a3 is requested. Moreover, the control arrangement 21 may be configured to maintain the third valve v3 in a closed state, in which no air is released/vent air from the third supply conduit cvia the third valve v3, when no braking of the number of wheels w3 arranged at the third wheel axis a3 is requested According to embodiments herein, the control arrangement 21 is configured to obtain a weight estimate of the vehicle 2. The weight estimate of the vehicle 2 may be represented by a current weight estimate of the vehicle 2. The weight estimate of the vehicle 2 may be obtained by estimating a current weight of the vehicle 2. According to such embodiments, the current weight of the vehicle 2 may be estimated based on at least one of torque and/or power data from a power source 3 of the vehicle 2, current inclination data of the vehicle 2 and/or of a surface 51 currently supporting the vehicle 2, a current speed of the vehicle 2, a current rate of change of the speed of the vehicle 2, and the like.

Current inclination data of the vehicle 2, and/or of a surface 51 currently supporting the vehicle 2, may be obtained using input from an inclinometer arranged on the vehicle 2, wherein the inclinometer is configured to measure a current inclination of the vehicle 2 relative to the gravitational field. As an alternative, or in addition, the control arrangement 21 may be configured to input a current inclination of the vehicle 2, and/or of a surface 51 supporting the vehicle 2, using map data together with a vehicle positioning device configured to provide a current position estimate of the vehicle 2. Such a vehicle positioning device may for example utilize a space-based satellite navigation system such as a Global Positioning System (GPS), The Russian GLObal NAvigation Satellite System (GLONASS), European Union Galileo positioning system, Chinese Compass navigation system, or Indian Regional Navigational Satellite System. As an alternative, or in addition, such a vehicle positioning device comprise one or more of a Radio Detection and Ranging (radar) sensor, a Light Detection and Ranging (lidar) sensor, an image capturing unit, such as a camera, an ultrasound sensor, or the like, for obtaining current position estimates of the vehicle l\/loreover, according to embodiments herein, the control arrangement 21 is configured to obtain a current pressure in the first supply conduit c1. The current pressure in the first supply conduit c1 may be obtained using one or more sensor devices configured to provide data representative of the current pressure in the first supply conduit c1. As an alternative, or in addition, the current pressure in the first supply conduit c1 may be obtained by inputting a current set pressure of the first supply conduit c According to the embodiments illustrated in Fig. 2, the control arrangement 21 is operably connected to a braking control arrangement 29. The braking control arrangement 29 may be configured to control operation of the service brake arrangement during normal driving of thevehicle 2. The term "normal driving of the vehicle 2", as used herein, means driving of the vehicle 2 during normal circumstances in which no malfunctions are detected which significantly impair the operational safety of the vehicle The braking control arrangement 29 may form part of an autonomous driving system of the vehicle 2. The autonomous driving system may be configured to drive, i.e., steer, brake, and propel, the vehicle 2 based on input from a number of sensor devices at least in part without human input. The number of sensor devices may comprise one or more of a Radio Detection and Ranging (radar) sensor, a Light Detection and Ranging (lidar) sensor, an image capturing unit, such as a camera, an ultrasound sensor, or the like.

According to the illustrated embodiments, the braking control arrangement 29 is configured to selectively output a request for retardation RR of the vehicle 2 by use of the parking brake system 1 during movement of the vehicle 2 to the control arrangement 21. The control arrangement 21 is configured to receive the request for retardation RR. ln Fig. 2, the request for retardation RR is schematically indicated inside a dashed box. The braking control arrangement 29 may be configured to output the request for retardation RR to the control arrangement 21 in case of detection of a malfunction at least potentially affecting the braking performance of the service brake arrangement of the vehicle 2. Purely as examples, such a malfunction may comprise a failure in electronic control of the service brake arrangement, loss in pressure control of a circuit of the service brake arrangement, or the like.

According to some embodiments, the braking control arrangement 29 is configured to output the request for retardation RR if a malfunction is detected and if a braking demand of the vehicle 2 is received. The braking demand of the vehicle 2 may be generated by the autonomous driving system of the vehicle 2, for example based on input from a number of sensor devices, or may be generated by an actuator, such as a brake pedal, arranged in a driver environment of the vehicle 2. ln Fig. 1, the driver environment of the vehicle 2 is schematically indicated.

The request for retardation RR comprises a magnitude of a requested retardation. The term "magnitude of the requested retardation", as used herein, may comprise a requested or desired deceleration rate of the vehicle 2. The magnitude of the requested retardation may be given in the unit meters per second squared. As an alternative, or in addition the, magnitude of the requested retardation may be represented by a requested or desired braking force of the vehicle According to embodiments herein, the control arrangement 21 is configured to, upon receipt of the request for retardation RR of the vehicle 2 by use of the parking brake system 1 during movement of the vehicle 2: - determine, based on the weight estimate of the vehicle 2 and a magnitude of the requested retardation, a first desired pressure level supplied to the first wheel brake arrangement b1, - determine, based on the first desired pressure level and the obtained current pressure in the first supply conduit c1, a first opening time duration of the first valve v1 required for reaching the first desired pressure level, and - control the first valve v1 to assume the open state during a first time period having the first opening time duration. ln this manner, the control arrangement 21 can control of the braking power provided by the first wheel brake arrangement b1 in a quick and accurate manner upon receipt of the request for retardation RR. Accordingly, in this manner, the control arrangement 21 can control of the retardation power applied to the vehicle 2 in a quick and accurate manner also in cases of a malfunction of a service brake arrangement of the vehicle 2. ln this manner, the control arrangement 21 can increase the operational safety of the vehicle The first desired pressure level supplied to the first wheel brake arrangement b1 may be determined such that first desired pressure level is set to lower values in case of higher weight estimates of the vehicle 2, and/or in case of higher magnitudes of the requested retardation, and vice versa. Moreover, obviously, the first opening time duration of the first valve v1 required for reaching the first desired pressure level may be set to longer first time periods in case of lower determined first desired pressure levels, and vice versa. Purely as an example, the first time period may be within the range of a few tenths of a second to a few seconds.

The control arrangement 21 may be configured to determine the first desired pressure level based on at least one of a configuration of the vehicle 2 and a configuration of the first wheel brake arrangement b1. The configuration of the vehicle 2 may comprise one or more of a configuration of wheel axles a1, a2, a3 of the vehicle 2, a configuration of wheels w1, w2, w3 of the vehicle 2, and the like. The configuration of the first wheel brake arrangement b1 may comprise a braking characteristic of the first wheel brake arrangement b1, and the like. l\/loreover, the control arrangement 21 may be configured to determine the first opening time duration based on at least one of a configuration of the first valve v1 and configuration of thefirst supply conduit c1. The configuration of the first valve v1 may comprise one or more of a size of the first valve v1, a flow characteristic of the first valve v1, and the like. The configuration of the first supply conduit c1 may comprise one or more of a size of the first supply conduit c1, a flow characteristic of the first supply conduit c1, a length of the first supply conduit c1, a diameter of the first supply conduit c1, and the like.

According to some embodiments, the control arrangement 21 is configured to obtain a current pressure in the second supply conduit c2. The current pressure in the second supply conduit c2 may be obtained using one or more sensor devices configured to provide data representative of the current pressure in the second supply conduit c2. As an alternative, or in addition, the current pressure in the second supply conduit c2 may be obtained by inputting a current set pressure of the second supply conduit c Moreover, the control arrangement 21 may be configured to, upon receipt of the request for retardation RR of the vehicle 2 by use of the parking brake system 1 during movement of the vehicle 2: - determine, based on the weight estimate of the vehicle 2 and a magnitude of the requested retardation, a second desired pressure level supplied to the second wheel brake arrangement b2, - determine, based on the second desired pressure level and the obtained current pressure in the second supply conduit c2, a second opening time duration of the second valve v2 required for reaching the second desired pressure level, and - control the second valve v2 to assume the open state during a second time period having the second opening time duration. ln this manner, the control arrangement 21 can control of the braking power provided by the second wheel brake arrangement b2 in a quick and accurate manner upon receipt of the request for retardation RR. Accordingly, in this manner, the control arrangement 21 can control of the retardation power applied to the vehicle 2 in a quick and accurate manner. Moreover, since a quick and accurate control can be provided of each of the first and second wheel brake arrangements b1, b2, conditions are provided for an increased braking stability of the vehicle 2 in cases of a malfunction of a service brake arrangement of the vehicle 2. ln this manner, the control arrangement 21 can further increase the operational safety of the vehicle The second desired pressure level supplied to the second wheel brake arrangement b2 may be determined such that second desired pressure level is set to lower values in case ofhigher weight estimates of the vehicle 2, and/or in case of higher magnitudes of the requested retardation, and vice versa. l\/loreover, obviously, the second opening time duration of the second valve v2 required for reaching the second desired pressure level may be set to longer second time periods in case of lower determined second desired pressure levels, and vice versa. Purely as an example, the second time period may be within the range of a few tenths of a second to a few seconds.

The control arrangement 21 may be configured to determine the second desired pressure level based on at least one of a configuration of the vehicle 2 and a configuration of the second wheel brake arrangement b2. The configuration of the second wheel brake arrangement b2 may comprise a braking characteristic of the second wheel brake arrangement b2, and the like.

Moreover, the control arrangement 21 may be configured to determine the second opening time duration based on at least one of a configuration of the second valve v2 and configuration of the second supply conduit c2. The configuration of the second valve v2 may comprise one or more of a size of the second valve v2, a flow characteristic of the second valve v2, and the like. The configuration of the second supply conduit c2 may comprise one or more of a size of the second supply conduit c2, a flow characteristic of the second supply conduit c2, a length of the second supply conduit c2, a diameter of the second supply conduit c2, and the like.

The control arrangement 21 may be configured to control the first and second valves v1, v2 such that the first and second valves v1, v2 are controlled to the respective open state at least substantially simultaneously upon receipt of the request for retardation RR.

Moreover, according to some embodiments, as is further explained below, the second desired pressure level may be different from the first desired pressure level. Likewise, the second opening time duration may be different from the first opening time duration.

That is, according to some embodiments, the control arrangement 21 is configured to determine the first desired pressure level and determine the second desired pressure level such that a difference between the first and second desired pressure levels increases with increased magnitudes of the requested retardation. ln this manner, it can be further ensured that a high degree of braking stability can be provided in various driving situations of the vehicleAs mentioned, according to the illustrated embodiments, the first wheel axle a1 is a front wheel axle of the vehicle 2 and the second wheel axle a2 is a rear wheel axle of the vehicle 2. According to these embodiments, as well as in other embodiments explained herein, the control arrangement 21 may be configured to determine the first desired pressure level and determine the second desired pressure level such that the second desired pressure level is set to a higher pressure level than the first desired pressure level when the magnitude of the requested retardation exceeds a threshold magnitude. ln this manner, it can be ensured that the first wheel brake arrangement b1 provides greater braking power than the second wheel brake arrangement b2 in situations in which the magnitude of the requested retardation exceeds the threshold magnitude. ln other words, it can be ensured that a higher braking power is applied to the number of wheels w1 arranged at the front wheel axle of the vehicle 2 than what is applied onto the number of wheels w2 arranged at the rear wheel axle of the vehicle 2 when the magnitude of the requested retardation exceeds the threshold magnitude. Thereby, it can be further ensured that a high degree of braking stability is provided in various driving situations of the vehicle According to some embodiments, the control arrangement 21 is configured to obtain a current pressure in the third supply conduit c3. The current pressure in the third supply conduit c3 may be obtained using one or more sensor devices configured to provide data representative of the current pressure in the third supply conduit c3. As an alternative, or in addition, the current pressure in the third supply conduit c3 may be obtained by inputting a current set pressure of the third supply conduit c l\/loreover, the control arrangement 21 may be configured to, upon receipt of the request for retardation RR of the vehicle 2 by use of the parking brake system 1 during movement of the vehicle 2: - determine, based on the weight estimate of the vehicle 2 and a magnitude of the requested retardation, a third desired pressure level supplied to the third wheel brake arrangement b3, - determine, based on the third desired pressure level and the obtained current pressure in the third supply conduit c3, a third opening time duration of the third valve v3 required for reaching the third desired pressure level, and - control the third valve v3 to assume the open state during a third time period having the third opening time duration. ln this manner, the control arrangement 21 can control of the braking power provided by the third wheel brake arrangement b3 in a quick and accurate manner upon receipt of therequest for retardation RR. Accordingly, in this manner, the control arrangement 21 can control of the retardation power applied to the vehicle 2 in a quick and accurate manner. Moreover, since a quick and accurate control can be provided of each of the first, second, and third wheel brake arrangements b1, b2, b3, conditions are provided for a further increased braking stability of the vehicle 2. ln this manner, the control arrangement 21 can further increase the operational safety of the vehicle The third desired pressure level supplied to the third wheel brake arrangement b3 may be determined such that third desired pressure level is set to lower values in case of higher weight estimates of the vehicle 2, and/or in case of higher magnitudes of the requested retardation, and vice versa. Moreover, obviously, the third opening time duration of the third valve v3 required for reaching the third desired pressure level may be set to longer third time periods in case of lower determined first desired pressure levels, and vice versa. Purely as an example, the third time period may be within the range of a few tenths of a second to a few seconds.

The control arrangement 21 may be configured to determine the third desired pressure level based on at least one of a configuration of the vehicle 2 and a configuration of the third wheel brake arrangement b3. The configuration of the third wheel brake arrangement b3 may comprise a braking characteristic of the third wheel brake arrangement b3, and the like.

Moreover, the control arrangement 21 may be configured to determine the third opening time duration based on at least one of a configuration of the third valve v3 and configuration of the third supply conduit c3. The configuration of the third valve v3 may comprise one or more of a size of the third valve v3, a flow characteristic of the third valve v3, and the like. The configuration of the third supply conduit c3 may comprise one or more of a size of the third supply conduit c3, a flow characteristic of the third supply conduit c3, a length of the third supply conduit c3, a diameter of the third supply conduit c3, and the like.

The control arrangement 21 may be configured to control the first and third valves v1, v3 such that the first and third valves v1, v3 are controlled to the respective open state at least substantially simultaneously upon receipt of the request for retardation RR. ln other words, according to these embodiments, the control arrangement 21 may be configured to control the first, second, and third valves v1, v2, v3 such that the first, second, and third valves v1, v2, v3 are controlled to the respective open state at least substantially simultaneously upon receipt of the request for retardation RR. The wording "at least substantially simultaneously" as used herein, may mean that the valves v1, v2, v3 referred to are controlled to an open state within a time period of less than 0.3 seconds, or less than 0.1 seconds.

Moreover, according to some embodiments, as is further explained below, the third desired pressure level may be different from the first desired pressure level. Likewise, the third opening time duration may be different from the first opening time duration.

That is, according to some embodiments, the control arrangement 21 is configured to determine the first desired pressure level and determine the third desired pressure level such that a difference between the first and third desired pressure levels increases with increased magnitudes of the requested retardation. ln this manner, it can be further ensured that a high degree of braking stability can be provided in various driving situations of the vehicle Moreover, as mentioned, according to the illustrated embodiments, the first wheel axle a1 is a front wheel axle of the vehicle 2 and the third wheel axle a3 is a rear wheel axle of the vehicle 2. According to these embodiments, the control arrangement 21 may be configured to determine the first desired pressure level and determine the third desired pressure level such that the third desired pressure level is set to a higher pressure level than the first desired pressure level when the magnitude of the requested retardation exceeds a threshold magnitude. ln this manner, it can be ensured that the first wheel brake arrangement b1 provides greater braking power than the third wheel brake arrangement b3 in situations in which the magnitude of the requested retardation exceeds the threshold magnitude. ln other words, it can be ensured that a higher braking power is applied to the number of wheels w1 arranged at the front wheel axle of the vehicle 2 than what is applied onto the number of wheels w3 arranged at the rear wheel axle of the vehicle 2 when the magnitude of the requested retardation exceeds the threshold magnitude. ln this manner, it can be further ensured that a high degree of braking stability is provided in various driving situations of the vehicle According to some embodiments, the control arrangement 21 may be configured to determine the third desired pressure level to correspond to the second desired pressure level. As an alternative, the control arrangement 21 may be configured to determine the third desired pressure level to be different from the second desired pressure level.

Moreover, according to some embodiments, the control arrangement 21 may be configured to determine the third opening time duration of the third valve v3 to correspond to the second opening time duration of the second valve v2. As an alternative, the control arrangementmay be configured to determine the third opening time duration of the third valve v3 to be different from the second opening time duration of the second valve v According to some embodiments, each of the first, second and third valves v1, v2, v3 comprises a blocking element configured to block a fluid path between a respective venting portion of the respective first, second and third valve v1, v2, v3 and the air supply system 10 when the respective first, second and third valve v1, v2, v3 is controlled to the respective open state. ln this manner, the pneumatic pressure in the respective first, second and third supply conduits c1, c3, c3 can be reduced in an even quicker manner.

According to some embodiments, the pneumatic parking brake system 1 may comprise a first blocking valve arranged between the first valve v1 and the air supply system 10, and wherein the control arrangement 21 is configured to control the first blocking valve to a closed state to block a fluid path between the first valve v1 and the air supply system 10 when the first valve v1 is controlled to the open state. ln this manner, the pneumatic pressure in the first supply conduit c1 can be reduced in an even quicker manner. According to some embodiments, such a first blocking valve is an integrated part of the first valve v1, wherein the first blocking valve is configured to assume a closed state to block a fluid path between a venting portion of the first valve v1 and the air supply system 10 when the first valve v1 is controlled to the open state.

Likewise, the pneumatic parking brake system 1 may comprise a second blocking valve arranged between the second valve v2 and the air supply system 10, and wherein the control arrangement 21 is configured to control the second blocking valve to a closed state to block a fluid path between the second valve v2 and the air supply system 10 when the second valve v2 is controlled to the open state. ln this manner, the pneumatic pressure in the second supply conduit c2 can be reduced in an even quicker manner. According to some embodiments, such a second blocking valve is an integrated part of the second valve v2, wherein the second blocking valve is configured to assume a closed state to block a fluid path between a venting portion of the second valve v2 and the air supply system 10 when the second valve v2 is controlled to the open state. l\/loreover, the pneumatic parking brake system 1 may comprise a third blocking valve arranged between the third valve v3 and the air supply system 10, and wherein the control arrangement 21 is configured to control the third blocking valve to a closed state to block a fluid path between the third valve v3 and the air supply system 10 when the third valve v3 is controlled to the open state. ln this manner, the pneumatic pressure in the third supplyconduit c3 can be reduced in an even quicker manner. According to some embodiments, such a third blocking valve is an integrated part of the third valve v3, wherein the third blocking valve is configured to assume a closed state to block a fluid path between a venting portion of the third valve v3 and the air supply system 10 when the third valve v3 is controlled to the open state.

Fig. 3 schematically illustrates a method 100 of controlling operation of a pneumatic parking brake system of a vehicle. The pneumatic parking brake system may be a pneumatic parking brake system 1 according to the embodiments illustrated in Fig. 2, i.e., a pneumatic parking brake system 1 of a vehicle 2 illustrated in Fig. 1. Therefore, below, simultaneous reference is made to Fig. 1 - Fig. 3, if not indicated othen/vise.

The method 100 is a method of controlling operation of a pneumatic parking brake system 1 of a vehicle 2, wherein the method 100 is performed by a control arrangement 21, and wherein the pneumatic parking brake system 1 comprises an air supply system 10, a first supply conduit c1 connecting the air supply system 10 to a first wheel brake arrangement b1 of the vehicle 2, wherein the first wheel brake arrangement b1 is configured to brake a number of wheels W1 arranged at a first wheel axle a1 of the vehicle 2, and a first valve v1 controllable to an open state in which the first valve v1 releases air from the first supply conduit c1. The method 100 comprises the steps of: - obtaining 103 a weight estimate of the vehicle 2, - obtaining 105 a current pressure in the first supply conduit c1, and upon receipt of a request for retardation RR of the vehicle 2 by use of the pneumatic parking brake system 1 during movement of the vehicle 2: - determining 110, based on the weight estimate of the vehicle 2 and a magnitude of the requested retardation, a first desired pressure level supplied to the first wheel brake arrangement b1, - determining 120, based on the first desired pressure level and the obtained current pressure in the first supply conduit c1, a first opening time duration of the first valve v1 required for reaching the first desired pressure level, and - controlling 130 the first valve v1 to assume the open state during a first time period having the first opening time duration.

As illustrated in Fig. 3, the step of determining 110 the first desired pressure level may comprise: - determining 111 the first desired pressure level based on at least one of a configuration of the vehicle 2 and a configuration of the first wheel brake arrangement bMoreover, as illustrated in Fig. 3, the step of determining 120 the first opening time duration may comprise: - determining 121 the first opening time duration based on at least one of a configuration of the first valve v1 and configuration of the first supply conduit c According to some embodiments, the pneumatic parking brake system 1 further comprises a second supply conduit c2 connecting the air supply system 10 to a second wheel brake arrangement b2 of the vehicle 2, wherein the second wheel brake arrangement b2 is configured to brake a number of wheels W2 arranged at a second wheel axle a2 of the vehicle 2, and a second valve v2 controllable to an open state in which the second valve v2 releases air from the second supply conduit c2. According to such embodiments, the method 100 may comprise the steps of: - obtaining 107 a current pressure in the second supply conduit c2, and upon receipt of the request for retardation RR of the vehicle 2 by use of the pneumatic parking brake system 1 during movement of the vehicle 2: - determining 112, based on the weight estimate of the vehicle 2 and a magnitude of the requested retardation, a second desired pressure level supplied to the second wheel brake arrangement b2, - determining 122, based on the second desired pressure level and the obtained current pressure in the second supply conduit c2, a second opening time duration of the second valve v2 required for reaching the second desired pressure level, and - controlling 132 the second valve v2 to assume the open state during a second time period having the second opening time duration.

Optionally, the step of controlling 130 the first valve v1 and the step of controlling 132 the second valve v2 may be performed such that the first and second valves v1, v2 are controlled to the respective open state at least substantially simultaneously.

According to some embodiments, the second desired pressure level is different from the first desired pressure level. l\/loreover, the second opening time duration may be different from the first opening time duration.

Moreover, according to some embodiments, the step of determining 110 the first desired pressure level and the step of determining 112 the second desired pressure level are performed such that a difference between the first and second desired pressure levels increases with increased magnitudes of the requested retardation.According to some embodiments, the first wheel axle a1 is a front wheel axle of the vehicle 2 and the second wheel axle a2 is a rear wheel axle of the vehicle 2, and wherein the step of determining 110 the first desired pressure level and the step of determining 112 the second desired pressure level are performed such that the second desired pressure level is set to a higher pressure level than the first desired pressure level when the magnitude of the requested retardation exceeds a threshold magnitude.

According to some embodiments, the pneumatic parking brake system 1 further comprises a third supply conduit c3 connecting the air supply system 10 to a third wheel brake arrangement b3 of the vehicle 2, wherein the third wheel brake arrangement b3 is configured to brake a number of wheels W3 arranged at a third wheel axle a3 of the vehicle 2, and a third valve v3 controllable to an open state in which the third valve v3 releases air from the third supply conduit c3. According to such embodiments, the method 100 may comprise the steps of: - obtaining 109 a current pressure in the third supply conduit c3, and upon receipt of the request for retardation RR of the vehicle 2 by use of the pneumatic parking brake system 1 during movement of the vehicle 2: - determining 113, based on the weight estimate of the vehicle 2 and a magnitude of the requested retardation, a third desired pressure level supplied to the third wheel brake arrangement b3, - determining 123, based on the third desired pressure level and the obtained current pressure in the third supply conduit c3, a third opening time duration of the third valve v3 required for reaching the third desired pressure level, and - controlling 133 the third valve v3 to assume the open state during a third time period having the third opening time duration. l\/loreover, as illustrated in Fig. 3, the method 100 may comprise the step of: - receiving 101 a request for retardation RR of the vehicle 2 by use of the pneumatic parking brake system 1 during movement of the vehicle The request for retardation RR may be received in the control arrangement 21 from a braking control arrangement 29. The step of receiving 101 the request for retardation RR is performed priorto the steps 110, 111, 112, 113, 120, 121, 122, 123, 130, 132, 133 referred to above. The steps 103, 105, 107, and 109 referred to above may be performed prior to, or after, the step of receiving 101 the request for retardation RR. lt will be appreciated that the various embodiments described for the method 100 are all combinable with the control arrangement 21 as described herein. That is, the control arrangement 21 may be configured to perform any one of the method steps 101, 103, 105, 107,109,110,111,112,113,120,121,122,123,130,132,and133 of the method Fig. 4 illustrates a computer-readable medium 200 comprising instructions which, when executed by a computer, cause the computer to carry out the method 100 according to some embodiments of the present disclosure. According to some embodiments, the computer- readable medium 200 comprises a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method 100 according to some embodiments.

One skilled in the art will appreciate that the method 100 of control|ing operation of a pneumatic parking brake system 1 of a vehicle 2 may be implemented by programmed instructions. These programmed instructions are typically constituted by a computer program, which, when it is executed in the control arrangement 21, ensures that the control arrangement 21 carries out the desired control, such as the method steps 101, 103, 105, 107,109,110,111,112,113,120,121,122,123,130,132,and133 described herein. The computer program is usually part of a computer program product 200 which comprises a suitable digital storage medium on which the computer program is stored.

The control arrangement 21 may comprise a calculation unit which may take the form of substantially any suitable type of processor circuit or microcomputer, e.g., a circuit for digital signal processing (digital signal processor, DSP), a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The herein utilised expression "calculation unit" may represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above.

The control arrangement 21 may further comprise a memory unit, wherein the calculation unit may be connected to the memory unit, which may provide the calculation unit with, for example, stored program code and/or stored data which the calculation unit may need to enable it to do calculations. The calculation unit may also be adapted to store partial or final results of calculations in the memory unit. The memory unit may comprise a physical device utilised to store data or programs, i.e., sequences of instructions, on a temporary or permanent basis. According to some embodiments, the memory unit may compriseintegrated circuits comprising silicon-based transistors. The memory unit may comprise e.g., a memory card, a flash memory, a USB memory, a hard disc, or another similar volatile or non-volatile storage unit for storing data such as e.g., ROIVI (Read-Only I\/|emory), PROIVI (Programmable Read-Only Memory), EPROIVI (Erasable PROIVI), EEPROIVI (Electrically Erasable PROIVI), etc. in different embodiments.

The control arrangement 21 may be connected to components of the vehicle 2, such as the air supply system 10, other parts of the pneumatic parking brake system 1, the braking control arrangement 29, the first valve v1, the second valve v2, the third valve v3, the powertrain 1, the transmission 14, the power source 3, and/or other parts of the vehicle 2 receiving and/or sending input and output signals. These input and output signals may comprise waveforms, pulses, or other attributes which the input signal receiving devices can detect as information and which can be converted to signals processable by the control arrangement 21. These signals may then be supplied to the calculation unit. One or more output signal sending devices may be arranged to convert calculation results from the calculation unit to output signals for conveying to other parts of the vehicle's control system and/or the component or components for which the signals are intended. Each of the connections to the respective components of the vehicle 2, such as the air supply system 10, other parts of the pneumatic parking brake system 1, the braking control arrangement 29, the first valve v1, the second valve v2, the third valve v3, the powertrain 1, the transmission 14, the power source 3, and/or other parts of the vehicle 2, for receiving and sending input and output signals may take the form of one or more from among a cable, a data bus, e.g., a CAN (controller area network) bus, a l\/IOST (media orientated systems transport) bus or some other bus configuration, or a wireless connection. ln the embodiments illustrated, the vehicle 2 comprises a control arrangement 21 but might alternatively be implemented wholly or partly in two or more control arrangements or two or more control units.

Control systems in modern vehicles generally comprise a communication bus system consisting of one or more communication buses for connecting a number of electronic control units (ECUs), or controllers, to various components on board the vehicle. Such a control system may comprise a large number of control units and taking care of a specific function may be shared between two or more of them. Vehicles of the type here concerned are therefore often provided with significantly more control arrangements than depicted in Fig. 2, as one skilled in the art will surely appreciate.The computer program product 200 may be provided for instance in the form of a data carrier carrying computer program code for performing at least some of the method steps 101, 103, 105,107,109,110,111,112,113,120,121,122,123,130,132,and133 according to some embodiments when being loaded into one or more calculation units of the control arrangement 21. The data carrier may be, e.g. a CD ROIVI disc, as is illustrated in Fig. 4, or a ROIVI (read-only memory), a PROIVI (programable read-only memory), an EPROIVI (erasable PROIVI), a flash memory, an EEPROIVI (electrically erasable PROIVI), a hard disc, a memory stick, an optical storage device, a magnetic storage device or any other appropriate medium such as a disk or tape that may hold machine readable data in a non-transitory manner. The computer program product may furthermore be provided as computer program code on a server and may be downloaded to the control arrangement 21 remotely, e.g., over an Internet or an intranet connection, or via other wired or wireless communication systems. lt is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only by the appended independent claims. A person skilled in the art will realize that the example embodiments may be modified, and that different features of the example embodiments may be combined to create embodiments other than those described herein, without departing from the scope of the present invention, as defined by the appended independent claims.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one or more stated features, elements, steps, components, or functions but does not preclude the presence or addition of one or more other features, elements, steps, components, functions, or groups thereof.

Claims

Claims 1. A method (100) of controlling operation of a pneumatic parking brake system (1) of a vehicle (2), the method (100) being performed by a control arrangement (21) and the pneumatic parking brake system (1) comprising: - an air supply system (10), - a first supply conduit (c1) connecting the air supply system (10) to a first wheel brake arrangement (b1) of the vehicle (2), wherein the first wheel brake arrangement (b1) is configured to brake a number of wheels (w1) at a first wheel axle (a1) of the vehicle (2), and - a first valve (v1) controllable to an open state in which the first valve (v1) releases air from the first supply conduit (c1), wherein the method (100) comprises the steps of: - obtaining (103) a weight estimate of the vehicle (2), - obtaining (105) a current pressure in the first supply conduit (c1), and upon receipt of a request for retardation (RR) of the vehicle (2) by use of the pneumatic parking brake system (1) during movement of the vehicle (2): - determining (110), based on the weight estimate of the vehicle (2) and a magnitude of the requested retardation, a first desired pressure level supplied to the first wheel brake arrangement (b1), - determining (120), based on the first desired pressure level and the obtained current pressure in the first supply conduit (c1), a first opening time duration of the first valve (v1) required for reaching the first desired pressure level, and - controlling (130) the first valve (v1) to assume the open state during a first time period having the first opening time duration.
2. The method (100) according to claim 1, wherein the step of determining (110) the first desired pressure level comprises: - determining (111) the first desired pressure level based on at least one of a configuration of the vehicle (2) and a configuration of the first wheel brake arrangement (b1).
3. The method (100) according to claim 1 or 2, wherein the step of determining (120) the first opening time duration comprises: - determining (121) the first opening time duration based on at least one of a configuration of the first valve (v1) and configuration of the first supply conduit (c1).
4. The method (100) according to any one of the preceding claims, wherein the pneumatic parking brake system (1) further comprises: - a second supply conduit (c2) connecting the air supply system (10) to a second wheel brake arrangement (b2) of the vehicle (2), wherein the second wheel brake arrangement (b2) is configured to brake a number of wheels (w2) at a second wheel axle (a2) of the vehicle (2), and - a second valve (v2) controllable to an open state in which the second valve (v2) releases air from the second supply conduit (c2), and wherein the method (100) comprises the steps of: - obtaining (107) a current pressure in the second supply conduit (c2), and upon receipt of the request for retardation (RR) of the vehicle (2) by use of the pneumatic parking brake system (1) during movement of the vehicle (2): - determining (112), based on the weight estimate of the vehicle (2) and a magnitude of the requested retardation, a second desired pressure level supplied to the second wheel brake arrangement (b2), - determining (122), based on the second desired pressure level and the obtained current pressure in the second supply conduit (c2), a second opening time duration of the second valve (v2) required for reaching the second desired pressure level, and - controlling (132) the second valve (v2) to assume the open state during a second time period having the second opening time durationThe method (100) according to claim 4, wherein the step of controlling (130) the first valve (v1) and the step of controlling (132) the second valve (v2) are performed such that the first and second valves (v1, v2) are controlled to the respective open state at least substantially simultaneouslyThe method (100) according to claim 4 or 5, wherein the second desired pressure level is different from the first desired pressure levelThe method (100) according to any one of the claims 4 - 6, wherein the second opening time duration is different from the first opening time duration_ The method (100) according to any one of the claims 4 - 7, wherein the step of determining (110) the first desired pressure level and the step of determining (112) the second desired pressure level are performed such that a difference between the first and second desired pressure levels increases with increased magnitudes of the requested retardationThe method (100) according to any one of the claims 4 - 8, wherein the first wheel axle (a1) is a front wheel axle of the vehicle (2) and the second wheel axle (a2) is a rear wheel axle of the vehicle (2), and wherein the step of determining (110) the first desired pressure level and the step of determining (112) the second desired pressure level are performed such that the second desired pressure level is set to a higher pressure level than the first desired pressure level when the magnitude of the requested retardation exceeds a threshold magnitudeA computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method (100) according to any one of the claims 1 - A computer-readable medium (200) comprising instructions which, when executed by a computer, cause the computer to carry out the method (100) according to any one of the claims 1 - A control arrangement (21) for controlling operation of a pneumatic parking brake system (1) of a vehicle (2), the pneumatic parking brake system (1) comprising: - an air supply system (10), - a first supply conduit (c1) connecting the air supply system (10) to a first wheel brake arrangement (b1) of the vehicle (2), wherein the first wheel brake arrangement (b1) is configured to brake a number of wheels (w1) at a first wheel axle (a1) of the vehicle (2), and - a first valve (v1) controllable to an open state in which the first valve (v1) releases air from the first supply conduit (c1), wherein the control arrangement (21) is configured to: obtain a weight estimate of the vehicle (2), obtain a current pressure in the first supply conduit (c1), and upon receipt of a request for retardation (RR) of the vehicle (2) by use of the parking brake system 1 during movement of the vehicle (2): - determine, based on the weight estimate of the vehicle (2) and a magnitude of the requested retardation, a first desired pressure level supplied to the first wheel brake arrangement (b1),determine, based on the first desired pressure level and the obtained current pressure in the first supply conduit (c1), a first opening time duration of the first valve (v1) required for reaching the first desired pressure level, and control the first valve (v1) to assume the open state during a first time period having the first opening time duration. 13. A pneumatic parking brake system (1) for a vehicle (2), the pneumatic parking brake system (1) comprising: an air supply system (10), a first supply conduit (c1) connecting the air supply system (10) to a first wheel brake arrangement (b1) of the vehicle (2), wherein the first wheel brake arrangement (b1) is configured to brake a number of wheels (w1) at a first wheel axle (a1) of the vehicle (2), a first valve (v1) controllable to an open state in which the first valve (v1) releases air from the first supply conduit (c1), and a control arrangement (21) according to claim 14. A vehicle (2) comprising: a first wheel axle (a1), a number of wheels (w1) arranged at the first wheel axle (a1), a first wheel brake arrangement (b1) configured to brake the number of wheels (w1), and a pneumatic parking brake system (1) according to claim 15. The vehicle (2) according to claim 14, wherein the vehicle (2) is a heavy road vehicle, such as a truck or a bus.