Utility vehicle and method for operating same

Abstract

The invention relates to a utility vehicle comprising at least one front axle and at least one rear axle. A first pneumatic brake circuit (2) is paired with the at least one rear axle, a second pneumatic brake circuit is paired with at least one front axle, and at least one supply inlet (7) of a valve unit (5) for supplying brake cylinders (6) of the at least one rear axle is connected to the first brake circuit (2). Each supply inlet (7) is connected to the first brake circuit (2) via a respective shuttle valve (8), and the shuttle valves (8) are additionally connected to another pneumatic circuit such that, by switching of the shuttle valves (8), the valve unit (5) is supplied with compressed air either from the first brake circuit (2) or from the other pneumatic circuit, wherein an electric control line (9) and / or a pneumatic control line (10) connects the valve unit (5) to a brake value transmitter of the second brake circuit.

Description

[0001] Commercial vehicle and method for its operation

[0002] The invention relates to a commercial vehicle according to the preamble of claim 1 and a method for operating the commercial vehicle according to the preamble of claim 3.

[0003] There are vehicles, in particular, but not exclusively, heavy three-axle vehicles and three-axle vehicles with a very low front-axle load share, which, for various reasons, cannot, in the event of failure of the rear-axle brake circuit, provide the legally prescribed auxiliary braking system, which must enable the vehicle to be stopped within a reasonable distance if the service braking system fails, with the still intact front-axle brake circuit of the service braking system.

[0004] Since the front axle brake circuit cannot meet the legally prescribed requirements of the auxiliary braking system on its own, braking action on the rear axle(s) must be applied by another means. The current state of the art is to use the parking brake system for this purpose. However, the parking brake system must meet more stringent requirements (braking effect, controllability, and responsiveness), which can generally only be achieved with increased pneumatic component and wiring complexity.

[0005] In addition, the solution mentioned

[0006] - not intuitive for the driver to use,

[0007] - difficult to dose and without ABS protection, and

[0008] - complex in the pneumatic circuitry.

[0009] The invention is based on the object of providing a novel commercial vehicle and a novel method for operating a commercial vehicle. This object is achieved according to the invention by a commercial vehicle having the features of claim 1 and by a method having the features of claim 3.

[0010] Advantageous embodiments of the invention are the subject of the subclaims.

[0011] A commercial vehicle has at least one front axle and at least one rear axle, with a pneumatic first brake circuit assigned to the at least one rear axle, and a pneumatic second brake circuit assigned to at least one front axle. At least one supply input of a valve unit for supplying brake cylinders of the at least one rear axle is connected to the first brake circuit. The valve unit includes at least one relay valve or a pressure modulator, which can also provide ABS functionality.According to the invention, each supply input is connected to the first brake circuit via a shuttle valve, wherein the shuttle valves are also connected to a further pneumatic circuit, so that the valve unit is supplied with compressed air by switching the shuttle valves either from the first brake circuit or from the further pneumatic circuit, wherein an electrical control line and / or a pneumatic control line connects the valve unit to a brake value transmitter of the second brake circuit.

[0012] According to the present invention, a redundant compressed air supply of the rear axle brake circuit is proposed by an additional, simple pneumatic connection to ensure the legal requirement for the auxiliary brake system even in the event of failure of the rear axle brake circuit with the service brake system.

[0013] This enables intuitive operation of the braking system: The driver achieves the auxiliary braking effect by pressing the foot brake pedal, eliminating the need to apply the parking brake while driving and removing a hand from the steering wheel. If the vehicle is equipped with ABS, this auxiliary braking effect is also protected by ABS, unlike when the parking brake is used, without ABS protection. The pneumatic circuitry according to the present invention allows for significantly lower pneumatic component and circuit complexity compared to the use of a parking brake system.

[0014] Embodiments of the invention are explained in more detail below with reference to a drawing. In this drawing:

[0015] Fig. 1 is a schematic partial view of a pneumatic circuit of a compressed air brake system of a motor vehicle.

[0016] The sole Figure 1 is a schematic partial view of a pneumatic circuit of a compressed air brake system 1 of a motor vehicle, in particular a motor vehicle with at least two or three axles, for example a commercial vehicle, with a multi-circuit brake system.

[0017] The compressed air brake system 1 has a first brake circuit 2, which is assigned to at least one rear axle of the motor vehicle, and a second brake circuit, not shown in detail, which is assigned to at least one front axle of the motor vehicle.

[0018] A valve unit 5 for supplying brake cylinders 6 of one or more rear axles is connected to the first brake circuit 2. For this purpose, the valve unit 5 has one, two, or more supply inlets 7 (two are shown as an example in Fig. 1), each of which is connected or connectable to the first brake circuit 2 via a shuttle valve 8.

[0019] In addition, the shuttle valves 8 are also connected to another pneumatic circuit, for example, a pneumatic auxiliary consumer circuit 4. By switching the shuttle valves 8, the valve unit 5 can therefore be supplied with compressed air either from the first brake circuit 2 or from the auxiliary consumer circuit 4.

[0020] For example, spring-loaded shuttle valves 8 are used.

[0021] In order to achieve vehicle braking with the legally prescribed minimum deceleration as simply as possible in the event of a failure of the first brake circuit 2, even with a high vehicle weight and / or a low front axle load, the valve unit 5 for braking the at least one rear axle is supplied with compressed air via the auxiliary consumer circuit 4 and the two shuttle valves 8 when the pressure in the first brake circuit 2 drops below a predefined threshold. An electrical control line 9 and / or a pneumatic control line 10 connects the valve unit 5 to a brake value transmitter of the second brake circuit. In one embodiment, the first brake circuit 2 is redundantly coupled to the auxiliary consumer circuit 4. Alternatively, another pneumatic circuit can also be used, for example a pneumatic circuit assigned to an air suspension.

[0022] The control of the valve unit 5, which contains, for example, two pressure modulators with ABS functionality, is primarily carried out via an electronic signal 9. However, if the electronics also fail (e.g. as a subsequent error), the control of the valve unit 5 for the brake cylinders 6 of the rear axle still functions via the pneumatic control line 10 from the brake value sensor.

[0023] If the brake signal transmitter and thus the pneumatic control line 10 is supplied via the second brake circuit or another pneumatic circuit independent of the first brake circuit 2, it is irrelevant whether the valve unit 5 detects a supposed fault of its own as a result of the pneumatic failure of the first brake circuit 2 and switches to redundancy or not.

[0024] If it can be ruled out that the pressure modulator goes into redundancy due to the pneumatic failure of the first brake circuit 2, the pneumatic control line 10 can be dispensed with, unless other reasons make this control line 10 necessary.

[0025] If the valve unit 5 consists of only one or more relay valves that can only be controlled pneumatically, the pneumatic control line 10 is required. This must still be functional in the event of a pneumatic failure of the first brake circuit 2, for example, by supplying the brake signal transmitter via the second brake circuit or another pneumatic circuit independent of the first brake circuit 2.

[0026] Together with the intact second brake circuit for the front axle, the legally required braking effect of the auxiliary braking system can be achieved with the (partially failed) service braking system, even in vehicles that cannot meet the legal requirements with the front axle brake circuit alone. These are primarily, but not exclusively, heavy three-axle vehicles and three-axle vehicles with a low front axle load share. In the former vehicles, the braking force on the individual front axle is not strong enough. In the latter vehicles, the axle load is insufficient to transfer sufficient braking force to the road. In both cases, braking must therefore be carried out by at least one rear axle in addition to the front axle.

[0027] List of reference symbols Pneumatic brake system First brake circuit Auxiliary consumer circuit Valve unit Brake cylinder Supply input Shuttle valve Electronic control line Pneumatic control line

Claims

Patent claims 1. A commercial vehicle with at least one front axle and at least one rear axle, wherein a pneumatic first brake circuit (2) is assigned to the at least one rear axle, wherein a pneumatic second brake circuit is assigned to the at least one front axle, wherein at least one supply inlet (7) of a valve unit (5), which contains at least one relay valve or at least one pressure modulator, is connected to the first brake circuit (2) for supplying brake cylinders (6) of the at least one rear axle, characterized in that each supply inlet (7) is connected to the first brake circuit (2) via a shuttle valve (8), wherein the shuttle valves (8) are also connected to a further pneumatic circuit, so that the valve unit (5) is supplied with compressed air either from the first brake circuit (2) or from the further pneumatic circuit by switching the shuttle valves (8),wherein an electrical control line (9) and / or a pneumatic control line (10) connects the valve unit (5) to a brake value transmitter of the second brake circuit., 2. Commercial vehicle according to claim 1, characterized in that the further pneumatic circuit is a pneumatic auxiliary consumer circuit (4) or the second brake circuit or a pneumatic circuit associated with an air suspension.

3. A method for operating a commercial vehicle according to one of claims 1 or 2, wherein the valve unit (5) is supplied with compressed air from the first brake circuit (2) in normal operation, characterized in that, when the pressure in the first brake circuit (2) drops below a predefined threshold value, the valve unit (5) for braking the at least one rear axle is supplied with compressed air via the further pneumatic circuit, in particular the auxiliary consumer circuit (4).

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