DE102017009060A1 - METHOD FOR CONTROLLING A VEHICLE BRAKE PLANT, VEHICLE BRAKE SYSTEM, VEHICLE WITH SUCH A PARKING BRAKE SYSTEM, COMPUTER PROGRAM AND COMPUTER PROGRAM PRODUCT - Google Patents

Abstract

The invention relates to a method for controlling a parking brake system (100) which is linked to a vehicle (1), wherein the parking brake system (100) has front compressed air braking means (22) for at least one front axle (6); rear air brake means (32) for at least one rear axle (10, 10 ', 10' '); and an air supply system (110) arranged to supply compressed air to the respective brake means (22, 32), the vehicle (1) associated with the parking brake system (100) comprising a kneeling function. The method includes the steps of identifying (s101) the activation of the parking brake system (100); Determining (s102) if the kneeling function is activated; Determining (s103) the road grade; and controlling (s104) the parking brake system (100) based on the determined information regarding the kneeling function and the road grade. The invention also relates to a parking brake system (100), a vehicle (1), a computer program (P) and a computer program product.

Description

TECHNICAL AREA

The present invention relates to a method of controlling a vehicle parking brake system, a vehicle parking brake system, a vehicle including such a system, a computer program and a computer program product according to the appended claims.

BACKGROUND

Heavy vehicles, such as trucks, buses, construction vehicles, etc., may be configured with the cabin floor and / or the first stage high above the road. This might be impractical for the driver of the vehicle, and therefore many vehicle owners have specific requirements regarding the distance between the cabin floor and the road. To meet these requirements, some vehicles are now equipped with a kneeling function that allows the front of the vehicle to be temporarily lowered. The air suspension of the front axle of the vehicle is typically used to lower the front of the vehicle. When the kneeling function is activated, the air suspension of the front axle is always contracted / lowered when the parking brake is activated. This solves the problem of the high cabin floor, but may cause another problem. The kneeling function, which uses the air suspension, consumes a lot of air, and it could be that the compressor of the vehicle is not able to supply the compressed air fast enough. Vehicles using the kneeling function may be, for example, garbage trucks or buses.

In a vehicle, the air suspension of a vehicle typically consumes the most air and the parking brake system is the second largest air consumer. Today's motor vehicles are mainly equipped for use when the vehicle is stationary, such as when parked, with a parking brake system. The parking brake system is separate from the conventional service brake system and typically includes air braking means, with one disposed on each braked wheel. The compressed air braking means are preferably spring brakes with a spring brake chamber and a prestressed spring device. Compressed air is supplied to the spring brake chamber and acts on the spring device so that it is compressed or decompressed, thereby releasing or locking the brake. When the spring device is compressed, no braking force is exerted on the associated wheel, and the parking brake is thus not detected. Thus, the air pressure in the spring brake chamber is normally such that the spring device is compressed. When the parking brake system is activated, the air pressure provided to the spring brake chamber is reduced, and the air in the spring brake chamber is released. The spring device is thereby decompressed, and the braking force is applied to the wheel. A vehicle that performs repeated start / stop operations and thus repeatedly uses the kneeling function also typically repeatedly turns the parking brake on and off. In some countries, it is even a legal requirement to engage the parking brake when loading garbage. The use of the air suspension system and the parking brake system at the same time can cause a problem by requiring more air than the vehicle compressor can provide. It would thus be advantageous to reduce the air consumption of the vehicle.

The publication EP 1382502 A1 discloses a method for controlling a parking brake of a vehicle, wherein the parking brake remains off during the actuation of the parking brake, if the air pressure of the service brake is sufficient to brake the vehicle. Thus, less compressed air is consumed. The publication US 2010181823 A discloses an air brake system for a vehicle in which an additional parking brake on the front axle is activated when the vehicle is parked on a steep slope. The document further discloses a function in which the actuation of the parking brake on the front axle is not allowed in order to avoid an unstable behavior when driving.

BRIEF SUMMARY OF THE INVENTION

Despite known solutions in the field, there is still a need to develop a method to reduce the consumption of compressed air in a vehicle.

An object of the present invention is to achieve an advantageous method for controlling a vehicle parking brake system, so that the air consumption of the vehicle parking brake system is reduced.

Another object of the invention is to achieve an advantageous vehicle parking brake system that is adapted to be controlled to reduce air consumption.

The objects mentioned herein are achieved by a method of controlling a parking brake system associated with a vehicle, a parking brake system, a vehicle including such a parking brake system, a computer program, and a computer program product according to the independent claims.

• – Identifizieren der Aktivierung der Feststellbremsanlage;
• – Bestimmen, ob die Kneeling-Funktion aktiviert ist;
• – Bestimmen der Straßensteigung; und
• – Steuern der Feststellbremsanlage basierend auf den bestimmten Informationen bezüglich der Kneeling-Funktion und der Straßensteigung.

In accordance with one aspect of the present invention, a method of controlling a parking brake system associated with a vehicle is provided. The parking brake system comprises front compressed air braking means for the wheels of at least one front axle; rear air brake means for at least one rear axle; and an air supply system arranged to supply compressed air to the respective braking means, wherein the vehicle associated with the parking brake system comprises an optional kneeling function that allows the front of the vehicle to be lowered. The method comprises the steps of:

• - identifying the activation of the parking brake system;
• - determining if the kneeling function is activated;
• Determining the road slope; and
• - Controlling the parking brake system based on the specific information regarding the kneeling function and the road grade.

It is commonly known that heavy vehicles may include a kneeling function in which the front of the vehicle may be temporarily lowered to facilitate entry and exit into and out of the vehicle. This is common, for example, in refuse collection vehicles and buses, but can also be used in other vehicles. Such a kneeling function typically uses the air suspension system of the vehicle, whereby the air suspension of the front axle is controlled to lower the front of the vehicle. Air suspension systems for leveling a vehicle are known to include a compressor unit that supplies compressed air to flexible bellows associated with each axle. The front axle (s) and the rear axle (s) of the vehicle respectively include such air spring bellows, and when the air pressure inflates the bellows of an axle, the vehicle chassis is lifted from that axle. A kneeling function thus means that the air suspension system is controlled in such a way that the air pressure in the bellows of the front axle is reduced. Thus, the bellows is emptied, and the chassis is lowered in the direction of the axis. The air suspension system is the largest consumer of air in a vehicle, and the parking brake system is the second largest consumer of air. The compressor units known today are only able to supply a limited amount of compressed air, which may not be enough for the air suspension, the kneeling function and the parking brake system. This is particularly a problem for the vehicles that perform frequent starts / stops and thereby often use the parking brake and the kneeling function, such as refuse trucks, buses, etc. When a parking brake system is activated, normally all the air braking means are on. For a vehicle with a front axle and two rear axles, this means that a maximum of six compressed air braking agents must be switched on / off and thereby much air is consumed. Turning on all braking means is not always necessary to stop the vehicle. By determining whether the kneeling function is activated; determining the road grade; and then controlling the parking brake system based on the determined information regarding the kneeling function and the road grade, the parking brake system may be controlled in response to the actual demand for braking force and compressed air. When the kneeling function is activated, a lot of compressed air is consumed, and it would therefore be desirable to reduce air consumption in another function of the vehicle.

Depending on the grade of the road, not all of the parking brake system brake means must be on to provide enough braking power to brake the vehicle. The steeper the slope, the more braking power is necessary and the more braking means must be turned on. However, with a substantially flat bottom, less braking force is needed and less braking means must be turned on. The method according to the invention thus makes it possible to control the parking brake system, so that only braking means which are necessary to provide the required braking force are switched on. By not turning on all the parking brake system brake means, the parking brake system air consumption may be reduced and more air pressure may be available to operate the vehicle.

The front air brake means and the rear air brake means are preferably spring brakes, with one on each braked wheel is arranged. Each spring brake preferably includes a spring brake chamber with a biased spring device. The spring device may be a coil spring. The air pressure which is supplied to the spring brake chamber via the main circuit of the parking brake, acts on the spring device so that it is compressed or decompressed and thereby the brake triggers (off) or determines (turns on). When the spring device is compressed, no braking force is applied to the associated wheel, and the parking brake is thus not detected. The braking force of the parking brake system thus increases when the air pressure in the respective braking means (spring brake) decreases. The air pressure in the spring brake chamber is normally such that the spring device is compressed. The air pressure in the spring brake chamber is normally about 8 to 8.5 bar and is provided by the air supply system. When the parking brake system is activated, the Reduced air pressure in the braking means, and when the parking brake system is deactivated, the air pressure in the braking means is increased again. Thus, a lot of compressed air is consumed when the parking brake system is repeatedly activated and deactivated.

The vehicle to which the parking brake system is linked preferably comprises at least three axles. The at least three axles preferably comprise a front axle and at least two rear axles. The parking brake system thus preferably comprises front brake means for the wheels of a front axle and rear brake means for the wheels of two rear axles. The two rear axles preferably comprise a drive axle and a trailing axle. The drive axle is connected to the travel unit of the vehicle, and the trailing axle is a so-called running axle, which is not part of the drive train. The parking brake system thus preferably comprises front brake means for the wheels of a front axle, rear brake means for the wheels of a drive axle and rear brake means for the wheels of a tag axle.

The method steps are preferably carried out on the basis of a control unit of the parking brake system. The control unit of the parking brake system may be the control unit of the internal combustion engine or any other vehicle control unit. The control unit may comprise a plurality of different control units.

The parking brake system is preferably activated manually by the operator of the vehicle. The parking brake system may be activated by manual actuation of a means for controlling a parking brake, such as a lever, a push button or the like. The control unit of the parking brake system is thus preferably arranged in communication with the means for controlling a parking brake. The control unit preferably identifies activation of the parking brake system by receiving a signal from the parking brake control means. The control unit may identify the activation of the parking brake system by means of a pressure sensor arranged in connection with the means for controlling a parking brake.

The kneeling function of the vehicle is preferably activated manually by the operator of the vehicle. The kneeling function is preferably activated only once. When the kneeling function is activated, the front part of the vehicle is lowered each time the parking brake system is activated. The kneeling function may be activated by a manual operation of a means for controlling a kneeling function such as a lever, a push button or the like. The parking brake control unit is preferably arranged in communication with the means for controlling a kneeling function. When the operator of the vehicle activates the kneeling function by operating the means for controlling a kneeling function, a signal is sent to the parking brake control unit. The control unit can thereby determine whether the kneeling function is activated or not.

According to one aspect of the invention, the parking brake system is controlled to turn on brake means on only one of the axles when the kneeling function is activated and the road grade is less than a predetermined angle. When the kneeling function is activated, much air is consumed and there is a greater need to reduce the air consumption of other functions of the vehicle. When the vehicle is on a low-grade road, less braking power is needed by the parking brake system to stop the vehicle. Thus, by switching on the brake means only one axis less air consumed by the parking brake system and yet provided a sufficient braking force. Thus, more air is available for the operation of the vehicle. Also, by reducing the air consumption of the parking brake system, the air supply system does not have to be regenerated so often, and the need for a large capacity air supply system is reduced. Turning on the brake means of only one axle reduces the wear of the compressor unit, thereby improving the life of the compressor unit and the air quality. This in turn reduces the total vehicle costs. The parking brake system is preferably controlled to turn on the braking means of all axles if the kneeling function is not active. When the parking brake system is activated, the air pressure supplied to the brake means via the main circuit is reduced, a passive valve in conjunction with the respective brake means opens, the air in the brake means is released and the brake means on all axles are turned on. The main circuit of the parking brake system is preferably adapted both for the air supply to the brake means and for the discharge of the air in the brake means. To turn on the braking means on only one axle, the step of controlling the parking brake system may include controlling at least one electronically controlled valve so that the braking means of all the axles remain off except one. The parking brake system is preferably controlled to turn on the brake means of only one of the axles by controlling an electronically controlled valve so as to prevent the draining of all the brake means except one. Thus, the braking means remain off. The at least one electronic controlled valve may be a release valve. For switching on the braking means of only one axis, the valve is preferably controlled such that the braking means of all axes except one via a line for compressed air in fluid communication with the air supply system. The line is preferably under constant pressure. Thus, enough air pressure to keep the brake means off is provided over the line. When the at least one release valve is controlled to an active state, the brake means, which are in communication with the release valve, are in fluid communication with the air supply system via the conduit. The compressed air from the air supply system ensures that the passive valve associated with the respective brake means is closed, thereby preventing the air in the brake means from being vented. Thus, the braking means remain off.

According to one aspect of the invention, the parking brake system is controlled to only engage the braking means of the at least one front axle when the kneeling function is activated and the road grade is less than a predetermined angle. Alternatively, the parking brake system is controlled to control only the braking means of a drive axle when the kneeling function is activated and the road grade is less than a predetermined angle. The drive axle can also be called a traction axle.

According to one aspect of the invention, the parking brake system is controlled to turn on only the braking means of the axle carrying the largest load when the kneeling function is activated and the road grade is less than a predetermined angle. Depending on, for example, the type of vehicle and the cargo loaded on the vehicle, the axles of the vehicle carry different loads. The larger the load, the greater the force that presses the wheels on the ground, and therefore the greater the frictional force between the wheel and the ground. Thus, when the braking means of only one axle are turned on, the choice of turning on the one carrying the greatest load ensures that the maximum braking effect is achieved so that the vehicle remains stationary.

The range of loads on the axles may be estimated during manufacture of the vehicle, for example, based on the weight of the vehicle components, the type of vehicle, the typical cargo, and the typical customer usage profiles. The axle carrying the largest load is thus preferably predetermined, and the parking brake system is configured based on the predetermined axle carrying the largest load. The parking brake system may be configured such that the braking means of the other axles may remain off when the braking means of the axle carrying the largest load is turned on. Alternatively, the load on the axles may be determined each time the parking brake system is activated. The load on the axles can then be determined by determining the pressure in the air suspension (bellows) of each axle. A certain pressure in the air suspension corresponds to a certain load on the axle. The relationship between the pressure of the air suspension and the load on the axle is usually known. Thus, the load on an axle can be estimated by determining the pressure of the air suspension. In this case, the parking brake system is preferably configured so that it is possible to turn on only the braking means of the axle carrying the largest load while the braking means of the other axles remain off. Thus, in one aspect of the invention, the method further includes determining the load on each axle and controlling the parking brake system to engage only the braking means of the axle with the largest load when the kneeling function is activated and the road grade is less than a predetermined angle is.

The predetermined angle is preferably in the range of 4 to 6 degrees. The predetermined angle may be 5 degrees. A road slope that is smaller than the predetermined angle thus corresponds to a substantially flat ground. When a vehicle is stopped on a substantially level ground, less braking force is required from the parking brake system, and it is thereby safe to turn on only the braking means of one axle.

Preferably, the step of controlling the parking brake system comprises turning on only one axle braking means when the kneeling function is activated and the road grade is in the range of 0 to 5 degrees. The step of controlling the parking brake system may include turning on the braking means of more than one axle when the kneeling function is activated and the particular road grade is greater than the predetermined angle. For example, in the case where the vehicle includes two axles, a front axle and a rear axle, the method may include turning on the braking means of all axles when the road grade is greater than 5 degrees. If the vehicle includes a front axle and two rear axles, the method may include engaging the brake means on two axles when the road grade is between 5 to 10 degrees and turning on the brake means on all axles when the road grade is between 10 and 15 degrees, include. In the event that the braking means are switched on more than one axis, the order of switching is preferably based on a predetermined strategy. Preferably, the Order of switching depends on the loads on the respective axes. For example, first the braking means of the axle carrying the largest load, then the braking means of the axle carrying the second largest load, etc. are turned on.

According to one aspect of the invention, the road grade is determined by an acceleration sensor arranged in communication with the parking brake system. The acceleration sensor is preferably arranged in communication with the parking brake control unit. The acceleration sensor constantly or intermittently determines the direction of acceleration and sends a signal indicative of the road grade to the control unit. The road grade may also be determined based on topographical data from a navigation system, such as a GPS or the like. The road gradient is defined as the inclination of the road on which the vehicle is standing with the parking brake system. The road slope can also be referred to as a road gradient.

According to one aspect of the invention, the parking brake system is controlled based on the outside temperature, the date, the road conditions and / or the road surface. The parking brake system may be controlled based on the mass of the vehicle. The parking brake system is preferably controlled to switch on only the brake means on one of the axles, depending on the outside temperature, the date, the road conditions and / or the road surface. When the kneeling function is activated and the road grade is less than a predetermined angle, the parking brake system according to the invention is controlled to turn on only the braking means on an axle. Depending on the weather conditions and / or the road conditions, however, this may not be a preferred solution. By determining the outside temperature and the date, it can be estimated whether the road is smooth or not, which may affect the braking force needed to keep the vehicle stationary. The parking brake system is thus preferably controlled based on the braking force needed to stop the vehicle. Ie. if the specified temperature is below zero and / or the date indicates that it is winter, it may be that the parking brake system is not controlled to turn on only the braking means on an axle, even if the kneeling function is activated and the road gradient is low. Likewise, cameras may be used to identify whether snow or ice is on the road, which may require a maximum braking force from the parking brake system. The information from the navigation systems regarding the road conditions may also be taken into account to determine whether the vehicle is on a gravel road or the like. If the vehicle is on a gravel road, it may not be enough to turn on only the braking means of an axle. Thus, in one aspect of the invention, the parking brake system is controlled to turn on only one axle braking means when the kneeling function is activated and the road grade is less than a predetermined angle, if predetermined outdoor temperature, date, road conditions and / or requirements are met. or the road surface are met. The parking brake system is preferably controlled to turn on the braking means of all axles when the kneeling function is activated and the road grade is less than a predetermined angle, if predetermined requirements regarding the outside temperature, the date, the road conditions and / or the road surface are not met ,

According to one aspect of the invention, the method further comprises switching on the brake means of all axles if the vehicle starts to run while only brake means on an axle are turned on. The method may thus include determining the wheel speed of the unbraked wheels and turning on the brake means of the unbraked wheels if the wheel speed indicates that the vehicle is running. The method may include turning on the brake means of at least one other axle if the vehicle begins to drive. This ensures safety.

According to one aspect of the invention, a parking brake system associated with a vehicle is provided. The parking brake system comprises front compressed air braking means for the wheels of at least one front axle; rear air brake means for the wheels of at least one rear axle; and an air supply system arranged to supply pressurized air to the respective brake means, the vehicle associated with the parking brake system including an optional kneeling function that allows the front of the vehicle to be lowered. The parking brake system includes a control unit adapted to identify the activation of the parking brake system; Determining if the kneeling function is activated; Determining the road slope; and controlling the parking brake system based on the determined information regarding the kneeling function and the road grade. As a result, a parking brake system is achieved, which allows the control of the parking brake system as a function of the required braking force and the need for compressed air.

The vehicle to which the parking brake system is linked preferably comprises an air suspension system for leveling the vehicle. The Kneeling function preferably uses the air suspension system, wherein the air suspension of the front axle is controlled to lower the front of the vehicle.

The air supply system of the parking brake system preferably comprises a compressor unit, at least one container and a valve arrangement which is arranged upstream of the brake means. The compressed air provided by the compressor unit is preferably stored in the at least one container. The valve arrangement is preferably arranged in connection with the at least one container in order to distribute the air from the container to the brake means via a main circuit. The compressor unit of the parking brake system may be the compressor unit of the air suspension system. The parking brake control unit is preferably arranged in communication with the air supply system. The control unit is preferably adapted to control the air supply system. The control unit is preferably adapted to control the compressor unit and the valve assembly.

The parking brake system is preferably adapted to be manually activated by the operator of the vehicle. The parking brake system may be adapted to be activated by a manual operation of a means for controlling a parking brake, such as a lever, a push button or the like. The control unit is preferably arranged in communication with the means for controlling a parking brake. The control unit may be adapted to receive a signal indicating the activation / deactivation of the parking brake system from the means for controlling a parking brake or from a pressure sensor arranged in connection with the means for controlling a parking brake.

The kneeling function of the vehicle is preferably adapted to be manually activated by the operator of the vehicle. The kneeling function may be adapted to be activated by manual operation of a means for controlling a kneeling function, such as a lever, a push button, or the like. The parking brake control unit is preferably arranged in communication with the means for controlling a kneeling function. The control unit may be adapted to receive a signal indicating the activation / deactivation of the kneeling function from the means for controlling a kneeling function. The control unit can thereby determine whether the kneeling function is activated or not.

According to one aspect of the invention, the control unit is adapted to control the parking brake system to turn on the brake means on only one of the axles when the kneeling function is activated and the road grade is less than a predetermined angle. Thus, less air is consumed by the parking brake system. The predetermined angle is preferably within the range of 4 to 6 degrees, preferably 5 degrees. A road slope smaller than the predetermined angle preferably corresponds to a substantially flat bottom. The control unit may be adapted to control at least one electronically controlled valve so that the braking means of all axes remain off except one. The control unit may be adapted to control at least one electronically controlled valve such that the brake means of all axes except one are in fluid communication with the air supply system when the kneeling function is activated and the road grade is less than the predetermined angle. The control unit may be adapted to control at least one electronically controlled valve so as to prevent the braking means of all axes from being deflated to one. The control unit may be adapted to turn on the brake means of only one axle when the kneeling function is activated and the road grade is within the range of 0 to 5 degrees. The control unit may be adapted to turn on the braking means of more than one axle when the kneeling function is activated and the particular road grade is greater than the predetermined angle. The control unit may be adapted to turn on the braking means on two axles when the road grade is between 5 to 10 degrees, and to turn on the braking means on three axles when the road grade is between 10 and 15 degrees.

The control unit is preferably adapted to control the parking brake system to only engage the braking means on the at least one front axle when the kneeling function is activated and the road grade is less than a predetermined angle. Alternatively, the at least one rear axle comprises a drive axle and the control unit is adapted to control the parking brake system to only engage the brake means on the drive axle when the kneeling function is activated and the road grade is less than a predetermined angle.

The control unit is preferably arranged in communication with an acceleration sensor for determining the road grade. The control unit is preferably adapted to receive from the acceleration sensor a signal indicative of the road grade. The control unit may also be adapted to determine the road grade based on topographical data from a navigation system.

The control unit is preferably adapted to control the parking brake system based on information regarding the outside temperature, the date, the road conditions and / or the road surface. The control unit is preferably adapted to control the parking brake system based on the mass of the vehicle. The control unit is preferably adapted to control the parking brake system based on the braking force needed to stop the vehicle. The control unit may be adapted to determine the outside temperature, the date, the road conditions and / or the road surface. The control unit may be adapted to determine whether predetermined outdoor temperature, date, road conditions and / or road surface requirements are met and, if so, to control the parking brake system to turn on only one braking means on an axle the Kneeling function is activated and the road grade is less than a predetermined angle. For example, the predetermined requirements may be that the temperature must be above a certain level; that it is not winter; that there is no ice or snow on the road; and / or that the road is a paved road. The outside temperature, date, road conditions and road surface are preferably determined by the control unit, which receives signals from various sensor devices in the vehicle according to conventional methods. The control unit is preferably adapted to control the parking brake system to turn on the braking means of all axles when the kneeling function is activated and the road grade is less than a predetermined angle if the predetermined requirement (s) with respect to the outside temperature, the date, the road conditions and / or the road surface is not met or are.

According to one aspect of the invention, the control unit may be adapted to switch on the braking means of all axles if the vehicle starts to drive while only the braking means on one axle are switched on. The control unit may thus be adapted to determine the wheel speed of the unbraked wheels and to turn on the braking means of the unbraked wheels if the wheel speed indicates that the vehicle is running. The control unit may be adapted to turn on the braking means of at least one other axle if the vehicle begins to drive.

According to one aspect of the invention, the control unit is adapted to control the parking brake system to turn on only the braking means of the axle carrying the largest load when the kneeling function is activated and the road grade is less than a predetermined angle. The axle carrying the largest load may be determined during manufacture of the vehicle, or it may be determined each time the parking brake system is activated.

When the axle that will carry the largest load is estimated during manufacture, the parking brake system is preferably configured based on the predetermined axle carrying the largest load. The parking brake system preferably comprises a release valve of a parking brake which, in this case, is arranged in fluid communication with the braking means of the axle (s) which does not carry the largest load. The release valve of a parking brake is preferably arranged in fluid communication with the air supply system such that when the release valve of a parking brake is in an active state, the brake means provides compressed air from the air supply system via a compressed air line. The braking means of all axes except one are preferably arranged via the release valve of a parking brake in fluid communication with the air supply system. The release valve of a parking brake is preferably an electronically controlled valve unit that can be controlled between an active state and an inactive state. If the release valve of a parking brake is in the active state, the air supply system is able to feed via the line compressed air into the braking means of the axles, which do not carry the largest load. This makes it possible for the braking means of the other axles to remain switched off when the braking means of the axle carrying the largest load is switched on. The parking brake control unit is thus preferably adapted to control the release valve of a parking brake such that the brake means is on only the axle carrying the largest load when the kneeling function is activated and the road grade is less than a predetermined angle , The control unit is thus preferably adapted to control the release valve of a parking brake to the active state when the parking brake system is activated, the kneeling function is activated and the road grade is less than a predetermined angle. Thus, compressed air is supplied to the braking means of the axles which do not carry the largest load, so that they remain switched off.

When the vehicle is loaded with cargo, the load on the axles may vary. It may therefore be desirable to repeatedly determine the axis carrying the largest load. When the axle bearing the largest load is determined each time a parking brake request is identified, the loads on the axles are preferably determined by determining the pressure in the air suspension (bellows) of each axle. A certain pressure in the Air suspension corresponds to a certain load on the axle. The relationship between the pressure of the air suspension and the load on the axle is usually known. Thus, the load on the axle can be estimated by determining the pressure of the air suspension. In this case, the parking brake system is preferably configured so that the braking means of all axles are arranged via a release valve assembly in fluid communication with the air supply system. The release valve assembly preferably includes a plurality of individually controlled release valves each disposed in fluid communication with the braking means of another axle. By controlling the release valves, the brake means of one of the axles can be supplied with compressed air and thereby remain off when the parking brake system is activated. The control unit is preferably adapted to control the release valves, so that only the brake means of the axle which carries the largest load is switched on, while the brake means of the other axles remain switched off. Thus, in one aspect of the invention, the control unit is adapted to determine the load on each axle and to control the parking brake system to turn on only the brake means of the axle carrying the largest load when the kneeling function is activated and the parking brake Street slope is less than a predetermined angle.

According to one aspect of the invention, the braking means of the axle carrying the largest load can be selected on the basis of a purely pneumatic valve or a purely pneumatic valve arrangement. An example of such an agent will be described below. The parking brake system may include a compressed air valve disposed in fluid communication with the air spring bellows and the braking means of a front axle and a rear axle. The compressed air valve is preferably configured so that the pressure in the air spring bellows acts on the surfaces of a movable valve element of the compressed air valve. The pressure acting on the surfaces may move the movable valve element between a first and a second position, each position corresponding to the engagement of braking means of either the drive axle or the front axle, whichever is more loaded. The parking brake system preferably also includes an electronically controlled valve, such as a solenoid valve. The electronically controlled valve may be connected between a first state in which the compressed air circuit (main circuit) of the braking means of all axes is connected to either the ambient air or the air supply, depending on whether the parking brake system is activated or not, and a second state in which the compressed air circuit the braking means for all axes except one is blocked, are controlled. When the compressed air circuit of the brake means is connected to the ambient air, the brake means can be drained and thus turned on, and when the compressed air circuit of the brake means is blocked, the brake means can not be drained / turned on. When the parking brake system is activated, the kneeling function is activated, and the road grade is less than a predetermined angle, the control unit is preferably adapted to control the electronically controlled valve to the second state, such that no air from the brake means of all axle up to can be drained to one over the circuit of the braking means. Thus, the braking means of all axes remain switched off except one. When the electronically controlled valve is in the second state, the compressed air valve is in fluid communication with the ambient air for the highest load axis. The greater the load on an axle, the higher the pressure in the air bellows of this axle. The compressed air valve is thus preferably configured so that the axle with the largest load pneumatically / mechanically moves the movable valve member into a position in which the braking means of that axle are in communication with the ambient air and can be drained and thereby turned on. Thus, the braking means is turned on only the axle with the largest load. The main circuit is preferably used for supplying air to the brake means and for venting the brake means. The compressed air valve is preferably arranged in fluid communication with the air spring bellows and the braking means of the front axle and the drive axle of the vehicle. It is usually known that in a vehicle having a drive axle and a trailing axle, the trailing axle always has a lower load than the drive axle. It is therefore not appropriate to turn on only the braking means of the trailing axle, and it is thus not necessary to be able to drain these brake fluid. The compressed air valve is preferably configured so that the pressure from the air spring bellows of the front axle and the drive axle acts on the lateral surfaces on the movable valve element from opposite directions. The relationship between the pressure in the air bag and the load on the axle is typically different for the front axle and the drive axle. Typically, the pressure-load ratio at the front axle is higher, and the lateral surface associated with the front axle must therefore be correspondingly smaller. Thus, when the load on the front axle is greatest, the pressure from the front axle air bags moves the movable valve member to a position that allows the front axle braking means to be released while preventing the drive axle braking means from being released. Likewise, when the load on the drive axle is greatest, the pressure from the drive axle air bellows moves the movable valve member to a position that allows the drive axle brake means to be released while preventing that the braking means of the front axle are lowered. Thus, only the braking means of the axle with the largest load is turned on. The above idea of switching on the braking means of only the axle carrying the largest load may take other forms, but the pressure of the air spring bellows, which is preferably conveyed via compressed air lines, is preferably applied to the surfaces of elements or parts corresponding to the Movement of the elements / parts lead. The movement of these elements / parts leads to the selection of the axle with the highest load and thus to the locking of the axle with less load. The surfaces may be deliberately designed to have specific relationships with one another.

The vehicle may be a hybrid vehicle. Such a hybrid vehicle includes an electric machine for locomotion, in addition to an internal combustion engine. The control unit may be the control unit of the internal combustion engine or may comprise a plurality of different control units. A computer may be connected to the control unit.

Additional objects, advantages and novel features of the present invention will become apparent to those skilled in the art from the following details and also from practicing the invention. Although the invention will be described below, it will be understood that it is not limited to the specific details described. Those skilled in the art having access to the present teachings will recognize other applications, changes, and integrations in other fields that are within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention and its further objects and advantages, the detailed description set forth below is to be read in conjunction with the accompanying drawings, in which like reference numerals designate like elements throughout the several drawings. Show it:

1 schematically a vehicle according to an embodiment of the invention;

2a schematically a parking brake system according to an embodiment of the invention;

2 B schematically a parking brake system according to an embodiment of the invention;

2c schematically a parking brake system according to an embodiment of the invention;

2d schematically a parking brake system according to an embodiment of the invention;

3 2 schematically illustrates a flowchart for a method of controlling a vehicle parking brake system according to an embodiment of the invention; and

4 schematically a control unit or a computer according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

As used herein, the term "connection" refers to a communication connection, which may be a physical connection, such as an opto-electronic communication line, or a non-physical connection, such as a wireless connection, e.g. B. a radio link or a high-frequency connection, can act. The connections provided here are shown as they are arranged for bidirectional communication. However, in some cases communication between the units may be unidirectional over such a connection.

1 schematically shows a side view of a vehicle 1 according to an embodiment of the invention. The vehicle 1 includes a movement unit 2 and a manual transmission 4 that with the locomotion unit 2 connected is. The vehicle 1 further comprises at least one front axle 6 with front wheels 8th and at least one rear axle 10 with rear wheels 12 , In this figure, the vehicle includes 1 two rear axles 10 wherein at least one of the rear axles is a drive axle. The at least one drive axle 10 is thus with the manual transmission 4 and the locomotion unit 2 connected. The vehicle 1 also includes a parking brake system 100 and an air suspension system 200 , The air suspension system 200 for leveling the vehicle 1 includes a compressor unit (not shown) that supplies compressed air to the flexible bellows 201 that with every axis 6 . 10 are linked. By increasing the air pressure inside the bellows 201 an axis 6 . 10 become the bellows 201 inflated and the chassis of the vehicle 1 gets off the axis 6 . 10 raised. By venting air from inside the bellows 201 an axis 6 . 10 become the bellows 201 deflated and the chassis goes in the direction of the axle 6 . 10 lowered. The vehicle 1 includes a kneeling function, in which the air suspension system 200 is controlled to remove air from the bellows 201 the front axle 6 let off, leaving the chassis on the front of the vehicle 1 is lowered. The vehicle 1 can be a heavy vehicle, for example a Truck, a bus, a forestry machine, a mining vehicle, a construction vehicle, an emergency vehicle, a refuse collection vehicle or the like. The vehicle 1 may be a hybrid vehicle, the two travel units 2 includes, namely, an electric machine and an internal combustion engine. The parking brake system 100 in the vehicle 1 is in 2a to 2d further described.

2a schematically forms a parking brake system 100 associated with a vehicle according to an embodiment of the invention. The vehicle with which the parking brake system 100 linked, the vehicle can 1 be like in 1 disclosed. The parking brake system 100 includes front air brake fluid 22 for braking the wheels 8th at least one front axle 6 ; rear air brake fluid 32 for braking the wheels 12 at least one rear axle 10 . 10 ' . 10 ''; and an air supply system 110 , which is arranged to supply compressed air to the respective braking means 22 . 32 supply. The wheels 8th attached to the at least one front axle 6 can be arranged as front wheels 8th be designated, and the wheels 12 at the at least one rear axle 10 . 10 ' . 10 '' can be arranged as rear wheels 12 be designated. A front brake fluid 22 is preferably on each front wheel 8th arranged. A rear brake fluid 32 is preferably on each rear wheel 12 arranged. In this example, the vehicle includes 1 two rear axles 10 . 10 ' . 10 '' and thus four rear brake means 32 , The two rear axles 10 include a drive axle 10 ' and a trailing axle 10 '' , The trailing axle 10 '' is the rear axle 10 , the furthest from the front axle 6 is removed.

The parking brake system 100 includes a control unit 120 adapted to identify the activation of the parking brake system 100 ; Determining if a kneeling function is activated; Determining the road slope; and controlling the parking brake system 100 based on the specific information regarding the kneeling function and the road grade. The control unit 120 is via a connection L110 for communication with the air supply system 110 arranged. A computer 130 can communicate with the control unit via a L130 connection 120 be arranged. The computer 130 can with the control unit 120 be detachably connected. The computer 130 can outside the vehicle 100 be arranged. The computer 130 Can be used to add software to the control unit 120 transferred to.

A means 140 for controlling a parking brake may communicate with the control unit via a connection L140 120 be arranged. This allows an operator of the vehicle 1 the middle 140 for controlling a parking brake to activate the parking brake system 100 manually press. The middle 140 for controlling a parking brake is thus preferably arranged in the vehicle cabin and may be a lever, a push button or the like of a parking brake.

The air supply system 110 the parking brake system preferably comprises a compressor unit (not shown), at least one container (not shown) and a valve assembly (not shown) upstream of the brake means 22 . 32 is arranged. The compressed air provided by the compressor unit is preferably stored in the at least one container. The valve assembly is preferably arranged in communication with the at least one container to remove the air from the container via a main circuit 40 on the brake fluid 22 . 32 to distribute. The compressor unit of the parking brake system 100 can also be the compressor unit of the air suspension system 200 of the vehicle 1 be like in 1 described. The compressed air provided by the compressor unit is thus both the braking means 22 . 32 the parking brake system 100 as well as the bellows 201 the air suspension system 200 to feed, as in 1 disclosed.

The front air brake 22 and the rear air brake 32 are preferably spring brakes, one on each braked wheel 8th . 12 is arranged. Each spring brake preferably includes a spring brake chamber with a biased spring device. The spring device may be a coil spring. The air pressure which is supplied to the spring brake chamber acts on the spring device, so that as it is compressed or decompressed and thereby releases the brake (off) or determines (turns on). When the spring device is compressed, no braking force is applied to the associated wheel 8th . 12 exercised, and the parking brake is thus not established. The braking force of the parking brake system 100 thus increases when the air pressure in the respective brake means (spring brake) 22 . 32 decreases. The air supply system 110 normally puts an air pressure over the main circuit 40 ready, which compresses the spring device. When the parking brake system 100 is activated, the air pressure is over the main circuit 40 all braking means 22 . 32 is reduced, a mechanical valve (not shown) associated with each braking means 22 . 32 is linked, it opens, allowing air in the braking means 22 . 32 is discharged and the spring device in each brake means 22 . 32 thereby decompressed. The main circuit 40 is preferably used to supply air to the braking means 22 . 32 feed and the air in the brake fluid 22 . 32 drain.

The parking brake system 100 also includes an electronically controlled release valve 50 a parking brake that is in fluid communication with the front brake means 22 at the front axle 6 and the rear brake means 32 the trailing axle 10 '' and the air supply system 110 is arranged. The brake means 22 . 32 the front axle 6 and the trailing axle 10 ' stand over a line for compressed air 42 and the release valve 50 a parking brake also in fluid communication with the air supply system 110 , The release valve 50 a parking brake can be controlled between an active state and an inactive state. In the inactive state can be over the main circuit 40 Air to the brake fluid 22 . 32 the front axle 6 and the trailing axle 10 '' be supplied or drained from it, depending on whether the parking brake system 100 is activated or not. In the active state is the connection with the main circuit 40 blocked and compressed air from the line 42 becomes the front axle 6 and the trailing axle 10 '' fed. So if the parking brake system 100 is activated, the air supply system 110 controlled to the braking means 22 . 32 over the main circuit 40 let off, so that all braking means 22 . 32 would be turned on. By simultaneously the release valve 50 a parking brake is controlled in the active state, the braking means 22 . 32 the front axle 6 and the trailing axle 10 '' supplied with an air pressure at which the braking means 22 . 32 stay off. Thus, only the braking means 32 the drive axle 10 ' drained and turned on. The brake means 22 . 32 not in fluid communication with the release valve 50 a parking brake are arranged, are preferably the braking means 22 . 32 which are arranged on the axle which carries the largest load. Thus, in this embodiment, the drive axle 10 ' as the axis 10 be viewed, which carries the largest load. By only the brake fluid 32 the drive axle 10 ' is turned on when the parking brake system 100 is activated, the air consumption of the parking brake system 100 be reduced. The control unit 120 is arranged via a connection L50 for communication with the release valve of a parking brake.

2 B schematically forms a parking brake system 100 associated with a vehicle according to an embodiment of the invention. The vehicle with which the parking brake system 100 linked, the vehicle can 1 be like in 1 disclosed. The parking brake system 100 is configured as in 2a described, with the difference that the release valve 50 a parking brake in fluid communication with the braking means 32 the drive axle 10 ' and the trailing axle 10 '' is arranged. When the release valve 50 a parking brake is thus in the inactive state, can via the main circuit 40 to the brake means 22 . 32 the drive axle 10 ' and the trailing axle 10 '' Air supplied or drained from it, depending on whether the parking brake system 100 is activated or not. In the active state is the connection with the main circuit 40 blocked and compressed air from the line 42 becomes the drive axle 10 ' and the trailing axle 10 '' fed. This means that when the parking brake system 100 is activated, the braking means 22 the front axle 6 are always on, whereas the braking means 32 the drive axle 10 ' and the trailing axle 10 '' can be left off by the release valve of a parking brake 50 is controlled. In this embodiment, the front axle 6 be regarded as the axle which carries the greatest load.

2c schematically forms a parking brake system 100 associated with a vehicle according to an embodiment of the invention. The vehicle with which the parking brake system 100 linked, the vehicle can 1 be like in 1 disclosed. The parking brake system 100 includes front air brake fluid 22 for braking the wheels 8th at least one front axle 6 ; rear air brake fluid 32 for braking the wheels 12 at least one rear axle 10 ; and an air supply system 110 , which is arranged to supply compressed air to the respective braking means 22 . 32 supply. The wheels 8th attached to the at least one front axle 6 can be arranged as front wheels 8th be designated, and the wheels 12 at the at least one rear axle 10 can be arranged as rear wheels 12 be designated. A front brake fluid 22 is preferably on each front wheel 8th arranged. A rear brake fluid 32 is preferably on each rear wheel 12 arranged. In this example, the vehicle includes 1 two rear axles 10 and thus four rear brake means 32 , The two rear axles 10 include a drive axle 10 ' and a trailing axle 10 '' , The trailing axle 10 '' is the rear axle 10 , the furthest from the front axle 6 is removed.

The parking brake system 100 includes a control unit 120 adapted to identify the activation of the parking brake system 100 ; Determining if a kneeling function is activated; Determining the road slope; and controlling the parking brake system 100 based on the specific information regarding the kneeling function and the road grade. The control unit 120 is via a connection L110 for communication with the air supply system 110 arranged. A computer 130 can communicate with the control unit via a L130 connection 120 be arranged. The computer 130 can with the control unit 120 be detachably connected. The computer 130 can outside the vehicle 100 be arranged. The computer 130 Can be used to add software to the control unit 120 transferred to.

A means 140 for controlling a parking brake may communicate with the control unit via a connection L140 120 be arranged. This allows an operator of the vehicle 1 the means 140 Manually operate the parking brake system to control a parking brake 100 to activate. The middle 140 for controlling a parking brake is thus preferably arranged in the vehicle cabin and may be a lever, a push button or the like of the parking brake.

The air supply system 110 the parking brake system preferably comprises a compressor unit (not shown), at least one container (not shown) and a valve assembly (not shown) upstream of the brake means 22 . 32 is arranged. The compressed air provided by the compressor unit is preferably stored in the at least one container. The valve assembly is preferably arranged in communication with the at least one container to remove the air from the container via a main circuit 40 to the brake fluid 22 . 32 to distribute. The compressor unit of the parking brake system 100 can also be the compressor unit of the air suspension system 200 of the vehicle 1 be like in 1 described. The compressed air provided by the compressor unit is thus both the braking means 22 . 32 the parking brake system 100 as well as the bellows 201 the air suspension system 200 to feed, as in 1 disclosed.

The front air brake 22 and the rear air brake 32 are preferably spring brakes, one on each braked wheel 8th . 12 is arranged. Each spring brake preferably includes a spring brake chamber with a biased spring device. The spring device may be a coil spring. The air pressure supplied to the spring brake chamber acts on the spring device so that it is compressed or decompressed, thereby releasing (disengaging) or detecting (engaging) the brake. When the spring device is compressed, no braking force is applied to the associated wheel 8th . 12 exercised, and the parking brake is thus not established. The braking force of the parking brake system 100 thus increases when the air pressure in the respective brake means (spring brake) 22 . 32 decreases. The air supply system 110 usually puts over the main circuit 40 an air pressure that compresses the spring device. When the parking brake system 100 is activated, the air pressure is over the main circuit 40 all braking means 22 . 32 is reduced, a mechanical valve (not shown) associated with each braking means 22 . 32 is linked, it opens, allowing the air in the braking means 22 . 32 is discharged and the spring device in each brake means 22 . 32 thereby decompressed. The main circuit 40 is preferably used to the braking means 22 . 32 Supply air and the air in the brake fluid 22 . 32 drain.

The parking brake system 100 further comprises a release valve assembly 52 in fluid communication with the braking means 22 . 32 all axes 6 . 10 ' . 10 '' and the air supply system 110 is arranged. The brake means 22 . 32 the axes 6 . 10 ' . 10 '' are in fluid communication with the air supply system 110 via the release valve arrangement 52 and the main circuit 40 and a pipe for compressed air 42 , The administration 42 is constantly under pressure. The release valve assembly 52 preferably includes a plurality of individually controlled release valves (not shown), each in fluid communication with the brake means 22 . 32 another axis 6 . 10 ' . 10 '' are arranged. Each release valve can be controlled between an active state and an inactive state. In the inactive state can be over the main circuit 40 Air to the brake fluid 22 . 32 be supplied or drained from it, depending on whether the parking brake system 100 is activated or not. In the active state, the compressed air is the braking means 22 . 32 over the line 42 fed. So if the parking brake system 100 is activated, the air supply system 110 controlled to the braking means 22 . 32 over the main circuit 40 let off, so that all braking means 22 . 32 would be turned on. One of the release valves of the release valve assembly 52 however, may be controlled to the active state at the same time to provide an air pressure at which the brake means 22 . 32 stay off. By controlling the release valve assembly 52 and thus the release valves can be the brake means 22 . 32 one of the axes 6 . 10 ' . 10 '' stay off when the parking brake system 100 is activated. The control unit 120 is via a connection L52 for communication with the release valve assembly 52 arranged.

The control unit 120 is preferably adapted to the parking brake system 100 to control the brake fluid 22 . 32 only on the axle 6 . 10 ' . 10 '' , which carries the largest load to turn on when the kneeling function is activated and the road slope is less than a predetermined angle. Ie. the control unit 120 is preferably adapted to the release valve assembly 52 to control, so that the release valves, with all axes 6 . 10 ' . 10 '' except the axis 6 . 10 ' . 10 '' carrying the largest load are in the active state when the kneeling function is activated and the road grade is less than a predetermined angle. The control unit 120 is also preferably adapted to the axis 6 . 10 ' . 10 '' to determine which carries the largest load. The control unit 120 can be adjusted to the load on each axle 6 . 10 ' . 10 '' by determining the pressure in the air bag of each axle 6 . 10 ' . 10 '' certainly becomes. The bellows 201 are in 1 disclosed. A certain pressure in the bellows 201 corresponds to a certain load on the axle 6 . 10 ' . 10 '' , The relationship between the pressure in the bellows 201 and the load on the axle 6 . 10 ' . 10 '' is usually known and in the control unit 120 saved.

2d schematically forms a parking brake system 100 associated with a vehicle according to an embodiment of the invention. The vehicle with which the parking brake system 100 linked, the vehicle can 1 be like in 1 disclosed. The parking brake system 100 includes front air brake fluid 22 for braking the wheels 8th at least one front axle 6 ; rear air brake fluid 32 for braking the wheels 12 at least one rear axle 10 ; and an air supply system 110 , which is arranged to supply compressed air to the respective braking means 22 . 32 supply. The wheels 8th attached to the at least one front axle 6 can be arranged as front wheels 8th be designated, and the wheels 12 at the at least one rear axle 10 can be arranged as rear wheels 12 be designated. A front brake fluid 22 is preferably on each front wheel 8th arranged. A rear brake fluid 32 is preferably on each rear wheel 12 arranged. In this example, the vehicle includes 1 two rear axles 10 and thus four rear brake means 32 , The two rear axles 10 include a drive axle 10 ' and a trailing axle 10 '' , The trailing axle 10 '' is the rear axle 10 , the furthest from the front axle 6 is removed.

The parking brake system 100 includes a control unit 120 adapted to identify the activation of the parking brake system 100 ; Determining if a kneeling function is activated; Determining the road slope; and controlling the parking brake system 100 based on the specific information regarding the kneeling function and the road grade. The control unit 120 is via a connection L110 for communication with the air supply system 110 arranged. A computer 130 can communicate with the control unit via a L130 connection 120 be arranged. The computer 130 can with the control unit 120 be detachably connected. The computer 130 can outside the vehicle 100 be arranged. The computer 130 Can be used to add software to the control unit 120 transferred to. The control unit 120 is preferably adapted to the parking brake system 100 to control the brake fluid 22 . 32 only on the axle 6 . 10 ' . 10 '' , which carries the largest load to turn on when the kneeling function is activated and the road slope is less than a predetermined angle.

A means 140 for controlling a parking brake may communicate with the control unit via a connection L140 120 be arranged. This allows an operator of the vehicle 1 the means 140 Manually operate the parking brake system to control a parking brake 100 to activate. The middle 140 for controlling a parking brake is thus preferably arranged in the vehicle cabin and may be a lever, a push button or the like of the parking brake.

The air supply system 110 the parking brake system preferably comprises a compressor unit (not shown), at least one container (not shown) and a valve assembly (not shown) upstream of the brake means 22 . 32 is arranged. The compressed air provided by the compressor unit is preferably stored in the at least one container. The valve assembly is preferably arranged in communication with the at least one container to remove the air from the container via a main circuit 40 on the brake fluid 22 . 32 to distribute. The compressor unit of the parking brake system 100 can also be the compressor unit of the air suspension system 200 of the vehicle 1 be like in 1 described. The compressed air provided by the compressor unit is thus both the braking means 22 . 32 the parking brake system 100 as well as the bellows 201 the air suspension system 200 supply. The bellows 201 are here and also in 1 displayed.

The front air brake 22 and the rear air brake 32 are preferably spring brakes, one on each braked wheel 8th . 12 is arranged. Each spring brake preferably includes a spring brake chamber with a biased spring device. The spring device may be a coil spring. The air pressure supplied to the spring brake chamber acts on the spring device so that it is compressed or decompressed, thereby releasing (disengaging) or detecting (engaging) the brake. When the spring device is compressed, no braking force is applied to the associated wheel 8th . 12 exercised and the parking brake is thus not established. The braking force of the parking brake system 100 thus increases when the air pressure in the respective brake means (spring brake) 22 . 32 decreases. The air supply system 110 usually puts over the main circuit 40 an air pressure that compresses the spring device. When the parking brake system 100 is activated, the air pressure is over the main circuit 40 all braking means 22 . 32 is reduced, a mechanical valve (not shown) associated with each braking means 22 . 32 is linked, it opens, allowing the air in the braking means 22 . 32 is discharged and the spring device in each brake means 22 . 32 thereby decompressed. The main circuit 40 is preferably used to supply air to the braking means 22 . 32 to feed, and to the air in the braking means 22 . 32 drain.

To the brake fluid 22 . 32 only the axis, 6 . 10 ' . 10 '' with the largest load to turn on, the parking brake system 100 be configured differently. The parking brake system 100 is preferably configured so that the pressure from the bellows 201 , which is preferably conveyed via compressed air lines, is applied to the surfaces of elements that lead to a movement of the elements. The movement of these elements leads to the selection of the axis 6 . 10 ' . 10 '' with the highest load while the axles 6 . 10 ' . 10 '' be blocked with a lower load. The surfaces may be deliberately designed to have mutually specific relationships.

The parking brake system 100 preferably comprises at least one purely pneumatic valve 54 that is in fluid communication with the air bags 201 and the braking means 22 . 32 the front axle 6 and the drive axle 10 ' is arranged. The brake means 22 . 32 the axis 6 . 10 ' , which carries the largest load, can by means of at least one purely pneumatic valve 54 to be selected. The compressed air valve 54 is preferably configured such that the pressure in the bellows 201 on the surfaces of a movable valve element (not shown) of the compressed air valve 54 acts. The pressure acting on the surfaces may move the movable valve member between a first and a second position, each position being responsive to the engagement of the brake means 22 . 32 either the drive axle 10 ' or the front axle 6 corresponds, whichever is more charged. The parking brake system 100 preferably also includes an electronically controlled valve 56 such as a solenoid valve. The control unit 120 is adapted to the electronically controlled valve 56 and is arranged in communication with the electronically controlled valve via a connection L56. The electronically controlled valve 56 can be between a first state in which the compressed air circuit (main circuit) 40 the brake fluid 22 . 32 all axes 6 . 10 ' . 10 '' either with the ambient air or the air supply via the air supply system 110 is connected, depending on whether the parking brake system 100 is activated or not, and a second state in which the compressed air circuit 40 the brake fluid 22 . 32 for all but one axle 6 . 10 ' . 10 '' is blocked, controlled. When the compressed air circuit 40 the brake fluid 22 . 32 Connected to the ambient air, the braking means 22 . 32 drained and thus turned on, and when the compressed air circuit 40 the brake fluid 22 . 32 blocked, the brake fluid can 22 . 32 not drained / turned on. When the parking brake system 100 is activated, the kneeling function is activated and the road grade is less than a predetermined angle, is the control unit 120 preferably adapted to the electronically controlled valve 56 to control in the second state, so no air from the braking means 22 . 32 all axes except one 6 . 10 ' over the compressed air circuit 40 the brake fluid 22 . 32 can be drained. Thus, the braking means remain 22 . 32 all axes except one 6 . 10 ' switched off. When the electronically controlled valve 56 in the second state is the compressed air valve 54 in fluid communication with the ambient air for the axle 6 . 10 ' with the biggest load. The greater the load on an axle 6 . 10 ' The higher the pressure in the bellows 201 this axis 6 . 10 ' , The compressed air valve 54 is thus preferably configured so that the axis 6 . 10 ' with the largest load pneumatically / mechanically moves the movable valve member into a position in which the braking means 22 . 32 this axis 6 . 10 ' in communication with the ambient air, and can be drained and thereby turned on. Thus, the braking means 22 . 32 only the axis, 6 . 10 ' switched on with the largest load.

It is usually known that in a vehicle with a drive axle 10 ' and a trailing axle 10 '' the trailing axle 10 '' always has a lower load than the drive axle 10 ' , It is therefore not appropriate, only the braking means 32 the trailing axle 10 '' turn it on, and it is therefore not necessary to use this braking means 32 to let off. Thus, the braking means 22 . 32 and the bellows 201 only the front axle 6 and the drive axle 10 ' with the compressed air valve 54 connected. The compressed air valve 54 is preferably configured so that the pressure from the bellows 201 the front axle 6 and the drive axle 10 ' acting on the lateral surfaces of the movable valve element from opposite directions. The parking brake system 100 is preferably configured so that when the load on the front axle 6 the largest is the pressure from the bellows 201 the front axle moves the movable valve member to a position that allows the brake means 22 to release the front axle, while preventing the brake fluid 32 the drive axle 10 ' be drained. Likewise moved when the load on the drive axle 10 ' the largest is the pressure from the bellows 201 the drive axle, the movable valve member in a position that allows the braking means 32 the drive axle, while preventing the brake means 22 the front axle 6 be drained. Thus, only the braking means 22 . 32 the axis 6 . 10 ' switched on with the largest load.

3 schematically illustrates a flowchart of a method for controlling a parking brake system 100 , which is assigned to a vehicle. The parking brake system 100 is preferably configured as in 2a . 2 B or 2c described. The vehicle with which the parking brake system 100 is linked, is preferably the vehicle 1 , as in 1 disclosed. The parking brake system 100 includes front air brake fluid 22 for the wheels 8th at least one front axle 6 ; rear air brake fluid 32 for the wheels 12 at least one rear axle 10 . 10 ' . 10 ''; and an air supply system 110 , which is arranged to supply compressed air to the respective braking means 22 . 32 to feed, the vehicle 1 that with the parking brake system 100 is linked, an air suspension system 200 and includes an optional kneeling feature that allows the front of the vehicle 1 lower by the air suspension of the at least one front axle 6 is controlled. The method includes the steps of identifying s101 the activation of the parking brake system 100 ; Determining s102 if the kneeling function is activated; Determining s103 of the road grade; and controlling s104 of the parking brake system 100 based on the specific information regarding the kneeling function and the road grade.

The method steps are preferably based on a control unit of the parking brake system 100 executed as in 2a . 2 B and 2c disclosed.

The step of identifying s101 the activation of the parking brake system 100 preferably comprises receiving a signal from a means 140 for controlling a parking brake. The middle 140 for controlling a parking brake, such as a lever, a push button or the like, is preferably by an operator of the vehicle 1 maneuvered. The control unit 120 the parking brake system 100 is preferably in communication with the agent 140 arranged to control a parking brake, and the control unit 120 thus identifies the request to activate the parking brake system 100 ,

The step of determining s102 whether the kneeling function is activated preferably comprises receiving a signal from a means for controlling a kneeling function. The kneeling function may be activated by manual operation of a means for controlling a kneeling function, such as a lever, a push button, or the like. The control unit 120 the parking brake system 100 is preferably arranged in communication with the means for controlling a kneeling function. When the operator of the vehicle 1 The Kneeling function activates by pressing the means to control a Kneeling function, a signal is sent to the control unit 120 the parking brake system 100 Posted. The control unit 100 thus determines whether the kneeling function is activated or not.

The step of determining road slope s103 preferably comprises receiving signals from an acceleration sensor in communication with the parking brake system 100 is arranged. The acceleration sensor is preferably in communication with the control unit 120 the parking brake system 100 arranged. The acceleration sensor continuously or intermittently determines the direction of the acceleration and sends a signal indicative of the road gradient to the control unit 120 , The road grade may also be determined based on topographical data from a navigation system, such as a GPS or the like.

The step of controlling s104 of the parking brake system 100 Based on the particular information regarding the kneeling function and the road grade, the brake fluid can be switched on 22 . 32 on only one of the axles 6 . 10 . 10 ' . 10 '' include when the kneeling function is activated and the road grade is less than a predetermined angle. The predetermined angle is preferably within the range of 4 to 6 degrees, preferably 5 degrees. When the kneeling function is activated, a lot of air is consumed and there is a greater need for air consumption of other functions of the vehicle 1 to reduce. If the vehicle 1 standing on a substantially level ground, less braking power from the parking brake system 100 to be provided. Thus, by switching on the brake means 22 . 32 only one axis 6 . 10 . 10 ' . 10 '' less air through the parking brake system 100 consumes, and it is still provided enough braking power. Thus, more air is available for the operation of the vehicle. To the brake fluid 22 . 32 on only one axis 6 . 10 . 10 ' . 10 '' may include the step of controlling s104 of the parking brake system 100 controlling at least one electronically controlled valve so as to prevent the braking means 22 . 32 all axes except one are drained. To the brake fluid 22 . 32 on only one axis 6 . 10 . 10 ' . 10 '' may include the step of controlling s104 of the parking brake system 100 controlling at least one release valve 50 . 52 include, so that the braking means 22 . 32 all axes except one in fluid communication with the air supply system 110 stand. Thus, enough air pressure will allow the brake fluid 22 . 32 stay off of the air supply system 110 provided.

The step of controlling s104 of the parking brake system 100 can turn on the brake fluid 22 only the at least one front axle 6 include when the kneeling function is activated and the road grade is less than a predetermined angle. Alternatively, the step of controlling s104 may be the parking brake system 100 the switching on of the brake means 32 only one drive axle 10 ' include when the kneeling function is activated and the road grade is less than a predetermined angle.

The step of controlling s104 of the parking brake system 100 Based on the particular information regarding the kneeling function and the road grade, the brake fluid can be switched on 22 . 32 only the axis, 6 . 10 . 10 ' . 10 '' , which carries the largest load, include when the kneeling function is activated and the road grade is less than a predetermined angle. By switching on the brake fluid 22 . 32 only the axis, 6 . 10 . 10 ' . 10 '' , which carries the largest load, becomes the air consumption of the parking brake system 100 while ensuring that enough brake force is provided. The method may further include determining the load on each axis 6 . 10 . 10 ' . 10 '' and controlling the parking brake system 100 include based on the specific load. The method may be determining the load on each axis 6 . 10 . 10 ' . 10 '' by determining the air pressure in the bellows 201 all axes 6 . 10 . 10 ' . 10 '' include.

The step of controlling s104 of the parking brake system 100 may be controlling the parking brake system 100 based on information regarding the outside temperature, the date, the road conditions and / or the road surface. The step may also include controlling the parking brake system 100 based on the mass of the vehicle 1 include. When the kneeling function is activated and the road grade is less than a predetermined angle, the parking brake system becomes 100 controlled according to the invention, only the braking means 22 . 32 on an axis 6 . 10 . 10 ' . 10 '' turn. Depending on the weather conditions and / or the road conditions, however, this may not be a preferred solution. By determining the outside temperature and the date, it can be estimated whether the road is smooth or not, which may affect the necessary braking force provided by the parking brake system 100 is to provide. Ie. if the specified temperature is below zero and / or the date indicates that winter is, it may be that the parking brake system 100 not controlled to only the braking means 22 . 32 on an axis 6 . 10 . 10 ' . 10 '' even if the kneeling function is activated and the road grade is low.

Likewise, cameras may be used to identify whether snow or ice is on the road, which may require a maximum braking force from the parking brake system. Information from navigation systems relating to road conditions may also be taken into account to determine if the vehicle is moving 1 located on a gravel road or the like. Thus, the parking brake system 100 be controlled to the braking means 22 . 32 only one axis 6 . 10 . 10 ' . 10 '' when the kneeling function is activated and the road grade is less than a predetermined angle if predetermined requirements regarding the outside temperature, the date, the road conditions and / or the road surface are met. The parking brake system 100 can be controlled to the braking means 22 . 32 all axes 6 . 10 . 10 ' . 10 '' when the kneeling function is activated and the road grade is less than a predetermined angle if predetermined requirements for outside temperature, date, road conditions and / or road surface are not met. Thus, the safety is paramount, and it ensures that always enough braking power through the parking brake system 100 provided.

4 schematically forms a device 500 from. The control unit 120 and / or the computer 130 , the or with reference to 2 can be described in one embodiment, the device 500 include. As used herein, the term "connection" refers to a communication connection, which may be a physical connection, such as an opto-electronic communication line, or a non-physical connection, such as a wireless connection, e.g. B. a radio link or a high-frequency connection, can act. The device 500 includes a non-volatile memory 520 , a data processing unit 510 and a read / write memory 550 , The non-volatile memory 520 has a first memory element 530 on which a computer program, for. As an operating system, is stored to the function of the device 500 to control. The device 500 Also includes a bus controller, a serial communication port, I / O means, an A / D converter, a time and date input / output unit, an event counter, and an interrupt controller (not shown). The non-volatile memory 520 also has a second memory element 540 ,

A computer program P is provided which provides routines for a method of controlling a parking brake system 100 that with a vehicle 1 in accordance with the invention. The computer program P includes routines for identifying a request to activate the parking brake system 100 , The computer program P includes routines for determining whether a kneeling function is activated. The computer program P includes routines for determining the road grade. The computer program P includes routines for controlling the parking brake system 100 based on the specific information regarding the kneeling function and the road grade. The Computer program P includes routines to only use the braking means 22 . 32 an axis 6 . 10 . 10 ' . 10 '' when the Kneeling function is activated and the road grade is less than a predetermined angle. The computer program P includes routines to only the braking means 22 . 32 the axis 6 . 10 . 10 ' . 10 '' , which carries the largest load to turn on when the kneeling function is activated and the road slope is less than a predetermined angle. The computer program P may be in executable form or in compressed form in memory 560 and / or in a random access memory 550 be saved.

When the data processing unit 510 is described as performing a particular function, it means that the data processing unit 510 a certain part of the program in the memory 560 is stored, or a certain part of the program, in the read / write memory 550 is stored, executes.

The data processing device 510 can with a data connection 599 via a data bus 515 communicate. The non-volatile memory 520 is for communication with the data processing unit 510 via a data bus 512 thought. The separate storage 560 is for communication with the data processing unit 510 via a data bus 511 thought. The read / write memory 550 is adapted to work with the data processing unit 510 via a data bus 514 to communicate.

When data is at the data port 599 are received, they temporarily become in the second memory element 540 saved. When received input data has been temporarily stored, the data processing unit is 510 ready to perform the code execution as described above.

Portions of the methods described herein may be used by the device 500 based on the data processing unit 510 that executes the program that is in the memory 560 or the read / write memory 550 is stored. When the device 500 executing the program, the methods described here are executed.

The foregoing description of the preferred embodiments of the present invention is provided by way of illustration and description. It is not intended to be exhaustive or to limit the invention to the variants described. Numerous modifications and variations will be apparent to those skilled in the art. The embodiments have been chosen and described in order to explain the principles of the invention and their practical applications as well as possible and to enable those skilled in the art to understand the invention for various embodiments and with the various modifications which are preferred for the particular use.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1382502 A1 [0004]
• US 2010181823 A [0004]

Claims (19)

Method for controlling a parking brake system ( 100 ) with a vehicle ( 1 ), wherein the parking brake system ( 100 ) front compressed air braking means ( 22 ) for the wheels ( 8th ) at least one front axle ( 6 ); rear air brake fluid ( 32 ) for the wheels ( 12 ) at least one rear axle ( 10 . 10 ' . 10 '' ); and an air supply system ( 110 ), which is arranged to supply compressed air to the respective braking means ( 22 . 32 ), wherein the vehicle ( 1 ) with the parking brake system ( 100 ) includes an optional kneeling function that allows the front of the vehicle ( 1 ), characterized by the steps of: - identifying (s101) the activation of the parking brake system ( 100 ); - determining (s102) if the kneeling function is activated; Determining (s103) the road grade; and - controlling (s104) the parking brake system (s104) 100 ) based on the specific information regarding the kneeling function and the road grade. Method according to claim 1, wherein the parking brake system ( 100 ) is controlled to the braking means ( 22 . 32 ) on only one of the axes ( 6 . 10 . 10 ' . 10 '' ) when the kneeling function is activated and the road grade is less than a predetermined angle. Method according to claim 1 or 2, wherein the parking brake system ( 100 ) is controlled to the braking means ( 22 ) only on the at least one front axle ( 6 ) when the kneeling function is activated and the road grade is less than a predetermined angle. Method according to claim 1 or 2, wherein the at least one rear axle ( 10 ) a drive axle ( 10 ' ) and the parking brake system ( 100 ) is controlled to the braking means ( 32 ) only on the drive axle ( 10 ' ) when the kneeling function is activated and the road grade is less than a predetermined angle. A method according to any one of claims 2 to 4, wherein the predetermined angle is within the range of 4 to 6 degrees. Method according to one of claims 2 to 5, wherein the parking brake system ( 100 ) is controlled to the braking means ( 22 . 32 ) of more than one axis ( 6 . 10 . 10 ' . 10 '' ) when the kneeling function is activated and the road grade is greater than the predetermined angle, with the number of axes ( 6 . 10 . 10 ' . 10 '' ) depends on how much greater than the predetermined angle is the road grade. Method according to one of the preceding claims, wherein the parking brake system ( 100 ) is controlled based on the vehicle mass, the outside temperature, the date, the road conditions and / or the road surface. Method according to one of the preceding claims, wherein the parking brake system ( 100 ) is controlled to the braking means ( 22 . 32 ) only the axis, ( 6 . 10 . 10 ' . 10 '' ), which carries the largest load, when the kneeling function is activated and the road grade is less than a predetermined angle. Parking brake system ( 100 ) with a vehicle ( 1 ), wherein the parking brake system ( 100 ) front compressed air braking means ( 22 ) for the wheels ( 8th ) at least one front axle ( 6 ); rear air brake fluid ( 32 ) for the wheels ( 12 ) at least one rear axle ( 10 . 10 ' . 10 '' ); and an air supply system ( 110 ), which is arranged to supply compressed air to the respective braking means ( 22 . 32 ), wherein the vehicle ( 1 ) with the parking brake system ( 100 ) includes an optional kneeling function that allows the front of the vehicle ( 1 ), characterized in that the parking brake system ( 100 ) a control unit ( 120 ) adapted to identify the activation of the parking brake system ( 100 ); Determining if the kneeling function is activated; Determining the road slope; and controlling the parking brake system ( 100 ) based on the specific information regarding the kneeling function and the road grade. System ( 100 ) according to claim 9, wherein the control unit ( 120 ) is adapted to the parking brake system ( 100 ) to control the braking means ( 22 . 32 ) only on one of the axes ( 6 . 10 . 10 ' . 10 '' ) when the kneeling function is activated and the road grade is less than a predetermined angle. System ( 100 ) according to claim 9 or 10, wherein the control unit ( 120 ) is adapted to the parking brake system ( 100 ) to control the braking means ( 22 . 32 ) only on the at least one front axle ( 6 ) when the kneeling function is activated and the road grade is less than a predetermined angle. System ( 100 ) according to claim 9 or 10, wherein the at least one rear axle ( 10 ) a drive axle ( 10 ' ) and the control unit ( 120 ) is adapted to the parking brake system ( 100 ) to control the braking means ( 32 ) only on the drive axle ( 10 ' ) when the kneeling function is activated and the road grade is less than a predetermined angle. System ( 100 ) according to one of claims 10 to 12, wherein the predetermined angle is within the range of 4 to 6 degrees. System ( 100 ) according to one of claims 10 to 13, wherein the control unit ( 120 ) is adapted to the braking means ( 22 . 32 ) of more than one axis ( 6 . 10 . 10 ' . 10 '' ) when the Kneeling function is activated and the road grade is greater than the predetermined angle, with the number of axles ( 6 . 10 . 10 ' . 10 '' ) depends on how much greater than the predetermined angle is the road grade. System ( 100 ) according to one of claims 9 to 14, wherein the control unit ( 120 ) is adapted to the parking brake system ( 100 ) based on the vehicle mass, the outside temperature, the date and / or the road surface to control. System ( 100 ) according to one of claims 9 to 15, wherein the control unit ( 120 ) is adapted to the parking brake system ( 100 ) to control the braking means ( 22 . 32 ) only the axis ( 6 . 10 . 10 ' . 10 '' ), which carries the largest load, when the kneeling function is activated and the road grade is less than a predetermined angle. Vehicle ( 1 ) comprising a parking brake system ( 100 ) according to any one of claims 9 to 16, Computer program (P), the computer program comprising program code for causing an electronic control unit ( 120 ; 500 ) or a computer ( 130 ; 500 ) connected to the electronic control unit ( 120 ; 500 ) is connected, the steps according to one of claims 1 to 8 executes. A computer program product comprising program code stored on a computer-readable medium for carrying out the method steps according to one of claims 1 to 8, when the computer program is stored on an electronic control unit ( 120 ; 500 ) or a computer ( 130 ; 500 ) connected to the electronic control unit ( 120 ; 500 ) is connected, expires.

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