Pneumatic supply system for an agricultural tractor

Abstract

Pneumatic supply device (12) for an agricultural tractor (10), comprising a compressed air source (16) for generating a compressed air stream (Q_komp), a cooler (20) for cooling the generated air stream (Q_komp), and a first air dryer (22) supplied with the cooled air stream (Q_komp), via whose outlet (24) a first pneumatic consumer group (26) can be supplied with dehumidified compressed air according to a first dehumidification and flow rate, and a second air dryer (28) supplied with the cooled air stream (Q_komp), via whose outlet (30) a second pneumatic consumer group (32) can be supplied with dehumidified compressed air according to a second dehumidification and flow rate.

Description

[0001] The invention relates to a pneumatic supply device for an agricultural tractor.

[0002] Such pneumatic supply systems are typically used to operate a pneumatic wheel brake system on a trailer attached to an agricultural tractor. They comprise a compressed air source designed as a compressor, a cooler for cooling the compressed air heated by compression, and a downstream air dryer for separating the condensate produced during cooling. To prevent corrosion from impairing the function and service life of the pneumatic wheel brake system, comparatively high demands are placed on the moisture-free nature of the supplied compressed air and thus on the dehumidification performance of the air dryer. To make the best possible use of the limited installation space in the agricultural tractor, the nominal flow rate of the air dryer is selected to be no higher than necessary in order to achieve the most compact design possible.A (simultaneous) compressed air supply to other pneumatically operated units is therefore only possible to a limited extent. This applies especially if these units are characterized by increased compressed air consumption, as is typical, for example, for the use of a blow-out gun connected externally via a compressed air coupling, a tire pressure control system, or pneumatically operated working units of attachments or additional equipment that can be attached to the agricultural tractor.

[0003] In view of this, it is the object of the present invention to improve a pneumatic supply device of the type mentioned at the outset with regard to its universal use.

[0004] This object is achieved by a pneumatic supply device for an agricultural tractor having the features of patent claim 1.

[0005] The pneumatic supply device according to the invention for an agricultural tractor comprises a compressed air source for generating a compressed air flow, a cooler for cooling the generated air flow, and a first air dryer fed with the cooled air flow, via the outlet of which a first pneumatic consumer group can be supplied with dehumidified compressed air corresponding to a first dehumidification and flow rate, and a second air dryer fed with the cooled air flow, via the outlet of which a second pneumatic consumer group can be supplied with dehumidified compressed air corresponding to a second dehumidification and flow rate.

[0006] By using separate air dryers, the specific requirements of different pneumatic consumer groups can be met with regard to the permissible moisture content of the supplied compressed air on the one hand, and the compressed air consumption on the other. This allows for universal use of the pneumatic supply system for a wide variety of consumer types.

[0007] The first pneumatic consumer group could, for example, be a pneumatic wheel brake system on a trailer attachable to the agricultural tractor. The second pneumatic consumer group, on the other hand, could be any other pneumatically operated unit with a higher compressed air consumption but lower requirements for the moisture-freeness of the supplied compressed air. Examples include a blow-out gun connected externally via a compressed air coupling, a tire pressure control system, or pneumatically operated working units of attachments or additional devices attachable to the agricultural tractor. In contrast to the first pneumatic consumer group, the latter does not place particularly high demands on the dehumidification performance of the air dryer, allowing it to be constructed comparatively compactly despite the desired increased flow rate.

[0008] In this case, the flow rate of the first or second air dryer is understood to be its nominal (i.e. maximum possible) flow rate, and its dehumidification capacity is understood to be the achievable degree of dehumidification of the air flow passing through.

[0009] Advantageous further developments of the pneumatic supply device according to the invention emerge from the subclaims.

[0010] Preferably, the cooled air flow is split and fed to the first and second air dryers in parallel. In this embodiment of the pneumatic supply system, an air dryer optimized for dehumidification and flow rate can be provided for each of the two pneumatic consumer groups.

[0011] According to a further embodiment of the pneumatic supply system, it is also conceivable for the cooled air flow to first pass through the second air dryer and then be divided to supply the second pneumatic consumer group and the first air dryer. The second air dryer thus serves as a pre-dryer for the first air dryer, whereby the latter can be constructed more compactly due to the reduced dehumidification capacity then required. The flow rate of the second air dryer or pre-dryer is selected such that it reliably covers the total compressed air consumption of the two pneumatic consumer groups.

[0012] In order to prioritize the air pressure supply to the first pneumatic consumer group, it can also be provided that the compressed air supply to the second pneumatic consumer group takes place via an upstream pressure switching valve, wherein the pressure switching valve assumes a closed position when the supply pressure falls below a predetermined level, so that the cooled air flow is available exclusively to the first pneumatic consumer group. This is particularly important if the first pneumatic consumer group is a braking system formed by a pneumatic wheel brake device of a trailer attachable to the agricultural tractor, the proper operation of which always has priority.

[0013] The pneumatic supply device for an agricultural tractor according to the invention is explained in more detail below with reference to the accompanying drawings. Components that are identical or comparable in terms of their function are designated by the same reference numerals. They show: Fig. 1 is a schematic block diagram of a first embodiment of the pneumatic supply device, and Fig. 2 a schematic block diagram of a second embodiment of the pneumatic supply device.

[0014] Fig. 1 shows a schematic block diagram of a first embodiment of the pneumatic supply device.

[0015] The pneumatic supply device 12 accommodated in an agricultural tractor 10 (not shown in detail) comprises a compressed air source 16 designed as a compressor 14 for generating a compressed air flow Q_comp, a cooler 20 connected to a liquid cooling circuit 18 for cooling the generated air flow Q_comp, and a first air dryer 22 fed with the cooled air flow Q_comp, via the outlet 24 of which a first pneumatic consumer group 26 is supplied with dehumidified compressed air corresponding to a first dehumidification and flow rate, and a second air dryer 28 fed with the cooled air flow Q_comp, via the outlet 30 of which a second pneumatic consumer group 32 is supplied with dehumidified compressed air corresponding to a second dehumidification and flow rate.The air dryers 22, 28 downstream of the cooler 20 each serve to separate the condensate produced during the cooling of the compression-heated air flow Q_comp, which is discharged via a respective drainage connection 34, 36. It should be noted that the cooler 20 is not necessarily designed as an active liquid-to-air cooler, but can also be a passive (convection-based) or active air-to-air cooler.

[0016] For example, the first pneumatic consumer group 26 is a pneumatic wheel brake device 38 of a trailer attachable to the agricultural tractor 10. The second pneumatic consumer group 32, on the other hand, is any other pneumatically operated unit 40 with a higher compressed air consumption but lower requirements regarding the moisture content of the supplied compressed air. Examples include a blow-out gun connectable externally via a compressed air coupling, a tire pressure control system, or pneumatically operated working units of attachments or additional devices attachable to the agricultural tractor 10.

[0017] According to the Fig. In the embodiment of the pneumatic supply device 12 shown in Figure 1, the cooled air flow Q_komp is divided and supplied in parallel to the first and second air dryers 22, 28 via associated first and second supply lines 42, 44. For each of the two pneumatic consumer groups 26, 32, an air dryer 22, 28 optimized in terms of dehumidification and flow rate is provided.

[0018] In order to prioritize the air pressure supply to the first pneumatic consumer group 26, the compressed air is applied to the second pneumatic consumer group 32 via a pressure switching valve 46 located upstream of the second air dryer 28 in the second supply line 44. Alternatively, the pressure switching valve 46 can also be located in the second supply line 44 between the second air dryer 28 and the second pneumatic consumer group 32. The pressure switching valve 46 assumes a closed position when the supply pressure falls below a predetermined supply pressure p_min, so that the cooled air flow Q_comp is exclusively available to the first pneumatic consumer group 26. This is particularly important when, as in this case, the first pneumatic consumer group 26 is a braking system formed by the pneumatic wheel brake device 38, the proper operation of which always has priority.

[0019] Fig. 2 shows a schematic block diagram of a second embodiment of the pneumatic supply device.

[0020] As can be seen, in this further embodiment of the pneumatic supply device 12, the cooled air flow Q_comp coming from the cooler 20 first passes through the second air dryer 28 and is then divided to supply the second pneumatic consumer group 32 and the first air dryer 22. The second air dryer 28 thus serves as a pre-dryer for the first air dryer 22 located in the first supply line 42. The flow rate of the second air dryer 28 or the pre-dryer formed thereby is selected such that it reliably covers the total compressed air consumption of the two pneumatic consumer groups 26, 32. The pressure switching valve 46 is arranged in the second supply line 44 between the second air dryer 28 and the second pneumatic consumer group 32.

Claims

[1] Pneumatic supply device for an agricultural tractor, comprising a compressed air source (16) for generating a compressed air flow (Q_komp), a cooler (20) for cooling the generated air flow (Q_komp), and a first air dryer (22) fed with the cooled air flow (Q_komp), via the outlet (24) of which a first pneumatic consumer group (26) can be supplied with dehumidified compressed air corresponding to a first dehumidification and flow rate, and a second air dryer (28) fed with the cooled air flow (Q_komp), via the outlet (30) of which a second pneumatic consumer group (32) can be supplied with dehumidified compressed air corresponding to a second dehumidification and flow rate. [2] Pneumatic supply device according to claim 1, characterized by that the cooled air flow (Q_komp) is divided and fed to the first and second air dryers (22, 28) in parallel. [3] Pneumatic supply device according to claim 1, characterized by that the cooled air flow (Q_komp) first passes through the second air dryer (28) and is then divided to supply the second pneumatic consumer group (32) and the first air dryer (22). [4] Pneumatic supply device according to at least one of the preceding claims, characterized by that the compressed air supply to the second pneumatic consumer group (32) takes place via an upstream pressure switching valve (46), wherein the pressure switching valve (46) assumes a closed position when a predetermined supply pressure (p_min) is undershot, so that the cooled air flow (Q_komp) is available exclusively to the first pneumatic consumer group (26).

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