Suction excavator with flow reversal and method for controlling same

Abstract

A suction excavator includes a suction hose with a suction opening for pneumatically receiving solid or liquid suction material using a fast-flowing air stream. The suction excavator has a separator for separating the suction material from the air stream, a filter unit for cleaning the air stream, a fan unit for generating the air stream, and a recirculation channel that is connected to the pressure side of the fan unit via a volume-controllable recirculation opening. A volume-controllable secondary air opening allows secondary air from the surroundings to be supplied to the suction side of the fan unit, downstream from the filter unit in the flow direction. The recirculation channel is fluidically coupleable to the suction hose to generate a positive pressure in the recirculation channel to blow out recirculation air through the suction hose.

Claims

1. A suction excavator comprising: a suction hose with a suction opening for pneumatically receiving solid or liquid suction material by means of a fast-flowing air stream; a separator for separating the suction material from the fast-flowing air stream; a filter unit (08), situated downstream from the separator in a flow direction, for cleaning the fast-flowing air stream; a fan unit for generating the fast-flowing air stream, a suction side of the fan unit being connected to an outlet of the filter unit, and a pressure side of the fan unit being connected to an exhaust air opening that is to open to a surrounding area; a recirculation channel that is connectable to the pressure side of the fan unit in a volume-controllable manner; wherein a volume-controllable secondary air opening is situated downstream from the filter unit in the flow direction that allows secondary air from the surrounding area to be supplied to the suction side of the fan unit, the recirculation channel being fluidically coupleable to the suction hose, and wherein a portion of recirculation air that is led through the recirculation channel is controllable to generate a positive pressure in the recirculation channel that results in recirculation air being blown out through the suction hose.

2. The suction excavator according to claim 1, wherein the fan unit includes at least two fans that are fluidically connected in series.

3. The suction excavator according to claim 1, wherein the secondary air opening opens into a flow section that extends between the filter unit and the suction side of the fan unit, and the secondary air opening includes an adjustable opening flap for changing an internal opening cross section between a closed position and a maximally open position.

4. The suction excavator according to claim 1, wherein the recirculation channel is additionally connected via a flow-regulating means to a parallel air duct that ends in a vicinity of the suction opening to deliver heated recirculation air at that location.

5. The suction excavator according to claim 1, further comprising blocking means which fluidically block at least the exhaust air opening, so that when the fan unit is activated, the air is circulated through the filter unit and the fan unit in order to heat the filter unit and the fan unit.

6. The suction excavator according to claim 1, further comprising at least one temperature sensor for determining the temperature of components and supplying the determined temperature to a control unit, which controls an operating mode and a volume regulation of various air streams.

7. The suction excavator according to claim 1, wherein the recirculation channel is coupleable to the separator via flow-regulating means, so that the recirculation channel is fluidically connected to the suction hose via the separator.

8. The suction excavator according to claim 5, wherein the blocking means fluidically blocks the suction hose, a parallel air duct, and the separator.

9. A method for controlling a suction excavator, comprising the following steps: selecting an operating mode from a group of operating modes that includes at least one suction mode and one blow-back mode, wherein the following steps are carried out in the suction mode: activating a fan unit for generating an air stream; setting flow-regulating means so that the air stream extends over a suction flow path, beginning at a suction opening of a suction hose, into a separator, subsequently through a filter unit to the fan unit, and from there to a surrounding area via an exhaust air opening); and wherein the following steps are carried out in the blow-back mode: activating the fan unit for generating the air stream; setting the flow-regulating means so that the air stream extends, at least partially, over a blow-back path, beginning at a secondary air opening, through the fan unit, into a recirculation channel to the suction hose, and up to the suction opening of the suction hose.

10. The method according to claim 9, wherein the group of operating modes also includes a short circuit mode in which the following steps are carried out: activating the fan unit for generating the air stream; setting the flow-regulating means so that the air stream extends, at least partially, over a closed short circuit flow path that runs at least through the filter unit to the fan unit, and from the fan unit back to the filter unit, wherein no air is supplied from outside and no air is emitted to the outside.

11. The method according to claim 10, wherein the group of operating modes also includes a suction mode having a heat-up function, in which the following steps are carried out: activating the fan unit for generating an air stream; setting the flow-regulating means so that the air stream extends partially over the suction flow path and partially over the short circuit flow path.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and particulars of the invention result from the following description of one preferred embodiment, with reference to the drawings, which show the following:

(2) FIG. 1 shows a schematic illustration of one embodiment of a suction excavator according to the invention, in suction mode;

(3) FIG. 2 shows a schematic illustration of the suction excavator, in short circuit mode; and

(4) FIG. 3shows a schematic illustration of the suction excavator, in blow-back mode.

DETAILED DESCRIPTION

(5) The schematic illustration shown in FIG. 1 depicts in a simplified fashion a suction excavator 01 according to the invention, which is operated in a suction mode. The illustrated flow arrows indicate the resulting air stream over a suction flow path. The suction excavator 01 includes a suction hose 02 with a suction opening 03 into which the suction material 04 which is to be received is drawn in in the suction mode. For this purpose, a fan unit 06 generates a suction air stream which, beginning at the suction opening 03, flows through a separator 07, then through a filter unit 08, to the fan unit 06. Coarse, heavy components of the suction material are deposited in the separator 07, while all fine, lightweight components are filtered out by the filter unit 08. The cleaned air is drawn into the fan unit 06 at a suction side 09, discharged at a pressure side 10, and emitted to an exhaust air opening 11, where it passes from the suction excavator into the surroundings.

(6) FIG. 2 shows the suction excavator 01 in a second operating state, namely, a so-called short circuit mode in which a fluidic short circuit is created between the suction side 09 and the pressure side 10 of the fan unit 06 in order to circulate and thus heat the air within the suction excavator. The illustrated flow arrows indicate the resulting air stream over a short circuit flow path. For this purpose, an exhaust air stream switch 12 is set in such a way that the exhaust air opening 11 is completely closed, and therefore the entire exhaust air stream is fed into a recirculation channel 13. The recirculation channel 13 may include multiple flow-regulating means 14 for supplying the recirculation air to various components and heating them. In the illustrated example, the recirculation air is supplied to the separator 07. Such guiding of the recirculation air stream results in heating of at least the suction material present at the top of the separator, the separator 07, the air ducts leading from the separator to the filter unit 08, and the filter unit 08 itself. The recirculation air stream that is directed into the separator 07 is drawn in once again by the fan unit 06, compressed, and thus reheated, and once more passes via the recirculation channel 13 into the separator 07. Since the air stream is further heated upon each pass through the fan 06, this operating mode results in very rapid heat-up of the components through which the air stream flows.

(7) In modified designs, the flow-regulating means 14 may be open at an outlet that is directed into the filter unit 08, as the result of which the entire recirculation air stream passes directly to the inlet of the filter unit 08.

(8) FIG. 3 shows the suction excavator 01 in a third operating state, namely, a blow-back mode. The illustrated flow arrows indicate the resulting air stream over a blow-back path. For this purpose, the exhaust air stream switch 12 is once again closed. A secondary air opening 16 is open, so that secondary air 17 is drawn in from the surroundings when the fan unit 06 is activated. The secondary air opening 16 is situated close, in terms of flow, to the suction side 09 of the fan unit, so that the flow resistance is lower than that in the air path across the filter unit 08. This ensures that secondary air is drawn in even when the recirculation air, which continues to be led through the recirculation channel 13, is transported through the filter unit. In the illustrated embodiment, the flow-regulating means 14 are partially open in the blow-back mode. Recirculation air is therefore directed into the separator 07. At the same time, portions of the recirculation air may be compressed and heated once again in a new pass through the fan 06. Due to the secondary air 17 that is additionally drawn in, the air volume in the separator increases, so that the pressure rises at that location, and heated recirculation air is pushed into the suction hose 02 and from there is led to the suction opening 03.

(9) In one modified embodiment, in the blow-back mode the recirculation air is led not through the separator, but, rather, from the recirculation channel directly to the suction hose.

LIST OF REFERENCE NUMERALS

(10) 01suction excavator 02suction hose 03suction opening 04suction material 05 06fan unit 07separator 08filter unit 09suction side 10pressure side 11exhaust air opening 12exhaust air stream switch 13recirculation channel 14flow-regulating means 15 16secondary air opening 17secondary air