Method for controlling or regulating the air pressure in a compressed air supply device

#This application contains subject matter related to U.S. application Ser. Nos. 12/273,382, 12/273,388, and 12/273,255, entitled “Compressed Air Supply System for a Utility Vehicle,” “Compressed Air Supply System for a Utility Vehicle,” and “Compressed Air Supply Device for a Utility Vehicle,” respectively, all filed on an even date herewith.

#The present invention relates to a method for controlling and/or regulating the air pressure in a compressed air supply device for a utility or commercial vehicle, with the steps: detection of at least one pressure value in the compressed air supply device and/or in vehicle components connected to the compressed air supply device, determination of a moisture value which represents the moisture content in an air filter unit belonging to the compressed air supply device, and opening of a shiftable clutch connecting a drive to a compressor, and also opening of a discharge valve of the compressed air supply device when the pressure value lies above a predetermined minimum value and the moisture value overshoots a predetermined threshold value.

#The invention relates, furthermore, to a compressed air supply device and to a utility vehicle having a compressed air supply device.

#FIG. 1 shows a diagrammatic illustration of a compressed air supply device according to the invention;

#FIG. 2 shows a diagrammatic illustration of a compressed air supply device according to the invention;

#FIG. 3 shows a diagrammatic illustration of a compressed air supply device according to the invention; and

#In the following description of the drawings, the same reference symbols designate identical or comparable components.

#FIG. 1 shows a diagrammatic illustration of a compressed air supply device according to the invention. A compressed air preparation plant 26 is illustrated. By means of this, compressed air supplied is filtered and is distributed to various compressed air consumers. An inlet connection 44 is provided, which is connected to a compressor 14 provided outside the compressed air preparation plant 26. An extraneous filing connection 46 is arranged parallel to the inlet connection 44. The compressed air supplied to one of the inlets 44, 46 is supplied to a filter unit 48 and from there, via a nonreturn valve 50, to a main supply line 52. Arranged in parallel on the main supply line 52 are two overflow valves 54, 56, via which connections 58, 60 for the service brake circuits of the utility vehicle are supplied with compressed air. A throttle 62, 64 and a nonreturn valve 66, 68 are arranged in each case parallel to the overflow valves, according to the present embodiment a flow, parallel to the flow through the overflow valves 54, 56, from the main supply line 52 to the connections 58, 60 of the service brake circuits being made possible. As a result, particularly during the refilling of the system, even in the case of low pressures in the main supply line 52, an early filling of the service brake circuit reservoirs can take place. It is likewise possible to provide the nonreturn valves in the opposite direction, this refilling benefit being dispensed with. A refilling of secondary consumers from the reservoirs of the service brake circuits is then made possible as a result. Furthermore, a pressure limiter 70 is provided in the main supply line 52. Two further lines branch off in parallel on the pressure-limited side of the pressure limiter 70, a connection 76 for the parking brake and the trailer brake system being supplied by means of one line via an overflow valve 72 and a nonreturn valve 74. The other line, via a nonreturn valve 42 and an overflow valve 78, feeds a connection 80 which is provided for actuating the compressor clutch 12. The overflow valve 78 is followed in a branching-off line by a further overflow valve 82 via which a further secondary consumer connection 84 is supplied.

#A plurality of pressure sensors 86, 88, 90, 92 are connected to the electronic control 32, the pressure sensor 88 measuring the pressure at the service brake connection 58, the pressure sensor 90 measuring the pressure at the service brake connection 60 and the pressure sensor 62 measuring the pressure directly downstream of the overflow valve 72 for the connection 76 of the parking brake and trailer. Furthermore, a temperature sensor 94 and a heating 96 are connected to the electronic control 32. Moreover, three solenoid valves 98, 100, 102 are connected to the electronic control 32: the pressure controller solenoid valve 98, the regeneration solenoid valve 100 and a solenoid valve 102 for the additional pressure control of the overflow valve 72. The solenoid valves 78, 100, 102 are designed as 3/2-way valves and are all closed in the currentless state. In the closed state, the pressure of the main supply line 52 is present at the inputs of the solenoid valves 98, 100, 102. To initiate a regeneration operation, it is necessary to apply current to the regeneration solenoid valve 100 and the pressure controller solenoid valve 98 and thus transfer them into their state not illustrated. The result of this is that dry compressed air is extracted from the service brake reservoirs via the main supply line 52 and then, bypassing the nonreturn valve 50, flows through the filter unit 48 in the opposite direction via the regeneration solenoid valve 100, a further nonreturn valve 104 and a throttle 106, in order then to flow via a discharge valve 106, changed over into its switching position, not illustrated on account of the changeover of the pressure controller solenoid valve 98, to a discharge 108 and from there out into atmosphere. The compressor 14 already mentioned, an internal combustion engine 10 and a shiftable clutch 12 connecting the compressor 14 to the internal combustion engine 10 are illustrated outside the compressed air preparation plant 26. The compressor 14 has an intake connection piece 22, via which the air to be compressed is sucked in. In the region of this air supply, a 3/2-way valve 18 is arranged, which in the present case is designed as an electrically pilot-controlled pneumatic valve, as is also illustrated separately. The pneumatic valve 18 has an inlet connection 110 to which a line 112 leading to the clutch connection 80 is connected. In this line 112, a nonreturn valve 40 is arranged, which permits a flow from the clutch connection 80 to the valve 18 and prevents a reverse flow. The valve 18 has an outlet connection which is coupled to a shift input 20 of the clutch 12 via a line 116. Via an electrical input 118 for the purpose of supplying a signal 16, the valve is connected to the electronic control 32 of the compressed air preparation plant 26 and to a ground which is picked off at a central plug 120.