Specialized civil engineering machine, in particular slotted wall milling machine

Abstract

The present invention relates to a special civil engineering machine, in particular a slurry wall cutter, comprising at least one rotating tool and a tool drive that is arranged within a housing of the special civil engineering machine and is sealed with respect to the environment by means of at least one bearing seal in the region of its shaft exit from the housing to the driven tool, characterized in that the bearing seal comprises at least two separate sealing elements, whose arrangement forms a sealing chamber located between the sealing elements, wherein a pressure compensation device is provided, which controls the chamber pressure in the sealing chamber in dependence on the ambient pressure of the special civil engineering machine.

Claims

1. A civil engineering machine, comprising at least one rotating tool and a tool drive arranged within a housing of the civil engineering machine and sealed with respect to the environment by at least one bearing seal in a region of a shaft exit from the housing to a driven tool, wherein the bearing seal comprises at least two separate sealing elements, whose arrangement forms a sealing chamber located between the sealing elements, and additionally comprising a pressure compensation device which controls pressure in the sealing chamber in dependence on ambient pressure of the civil engineering machine.

2. The civil engineering machine according to claim 1, wherein an outer one of the sealing elements seals the sealing chamber with respect to the environment, the outer sealing element has material-resistant properties with respect to a supporting liquid surrounding the sealing element, and the outer sealing element is configured as a mechanical seal.

3. The civil engineering machine according to claim 1, wherein an inner one of the sealing elements seals the sealing chamber with respect to the housing, and the inner sealing element provides a pressure-independent sealing effect.

4. The civil engineering machine according to claim 3, wherein the inner sealing element seals the sealing chamber with respect to a transmission space of the tool drive.

5. The civil engineering machine according to claim 3, wherein the inner sealing element is an elastomer seal.

6. The civil engineering machine according to claim 1, wherein the sealing chamber is hermetically sealed with respect to the environment of the civil engineering machine and/or the housing or a transmission space of the tool drive.

7. The civil engineering machine according to claim 6, wherein a pump sucks in lubricant from the housing or a transmission space of the tool drive and pumps the same into the sealing chamber.

8. The civil engineering machine according to claim 6, additionally comprising a pump, wherein at a pressure outlet of the pump, a pressure limiting valve is provided to adjust a generated chamber pressure, and the pressure limiting valve provides a control pressure port connected to a membrane via a control pressure volume, by which membrane changes of the ambient pressure are forwarded to the control pressure volume in the control pressure port.

9. The civil engineering machine according to claim 8, wherein by the return flow from the pressure limiting valve, an active oil lubrication of drive or transmission components of the tool drive is effected, whose lubrication otherwise is not ensured during operation.

10. The civil engineering machine according to claim 1, wherein the sealing chamber is relieved towards the housing via at least one throttle.

11. The civil engineering machine according to claim 10, wherein the sealing chamber is relieved towards a transmission space via said at least one throttle.

12. The civil engineering machine according to claim 1, wherein the pressure compensation device comprises a pump whose pressure outlet is connected to the sealing chamber to pressurize the same with the required chamber pressure in dependence on the ambient pressure.

13. The civil engineering machine according to claim 12, comprising a pressure limiting valve which is spring-biased, and a setpoint differential pressure between the chamber pressure and the ambient pressure is adjustable via the spring bias.

14. The civil engineering machine according to claim 13, wherein the pressure limiting valve has an adjustable spring bias.

15. The civil engineering machine according to claim 12, wherein an outlet of a pressure limiting valve is connected to the housing.

16. The civil engineering machine according to claim 15, wherein the outlet of the pressure limiting is connected to a transmission space of a tool drive.

17. The civil engineering machine according to claim 1, wherein in a return line from a pressure limiting valve to the housing, at least one heat exchanger and/or oil filter and/or oil analysis device is integrated.

18. The civil engineering machine according to claim 1, wherein the pressure compensation device comprises a pump whose pressure outlet is connected to the sealing chamber to pressurize the same with the required chamber pressure in dependence on the ambient pressure, and the pump is adapted to suck in lubricant from the housing or a transmission space of the tool drive and pump the lubricant into the sealing chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and properties of the invention will be explained in detail below with reference to exemplary embodiments. In the drawing:

(2) FIG. 1: shows a hydraulic circuit diagram of the slurry wall cutter of the invention according to a first exemplary embodiment, and

(3) FIG. 2: shows a hydraulic circuit diagram of a configuration slightly modified with respect to the exemplary embodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) FIG. 1 shows a hydraulic circuit diagram for a slurry wall cutter according to the invention, which comprises a non-illustrated housing in which a cutter drive is accommodated. The cutter drive comprises the two milling wheel gears 1, which are driven by a common hydraulic motor 2. A plurality of drive shafts exit from the housing, which must be sealed via the bearing seals 9, 10 yet to be explained in detail below.

(5) Regardless of the state of movement of the milling wheel drive and therefore separately supplied with energy via a constant hydraulic drive 12, a pump unit 3 sucks in a small constant oil flow from the transmission interior 4, which flows through the pressure limiting valve 5. The pressure limiting valve 5 has an adjustable spring bias and a control pressure port 7. Via the membrane 6, the ambient pressure acts directly on an oil volume that acts on the control pressure port 7 of the valve 5.

(6) The pressure generated by the pump 3 and controlled by means of the pressure limiting valve 5 is applied to the oil-filled sealing chamber 8, which is sealed against the environment by a mechanical seal 9 and by an elastomer seal 10 against the interior space of the transmission 1.

(7) Due to the high content of air in the total volume of the transmission interior, atmospheric pressure more or less exists in the transmission space 4 in dependence on the temperature, regardless of the penetration depth of the drive in the supporting liquid. On the other hand, the ambient pressure in the supporting liquid with the usual working depths can assume values between atmospheric pressure and about 20-25 bar.

(8) The seals 9 and 10 divide the entire sealing task of the bearing seal into two sub-tasks for which they are each designed:

(9) Seal 9 is able to withstand the abrasive and corrosive properties of the surrounding supporting liquid, but to do so needs a pressure in the sealing chamber 8 that is to be maintained as exactly as possible and lies about 2 bar above the pressure of the surrounding supporting liquid, with a tolerance of less than 1 bar.

(10) Seal 10 can withstand the potentially high differential pressure between environment and transmission interior, but to do so requires the cleanliness of the surrounding fluids.

(11) The pressure limiting valve 5 influences the pressure in the sealing chamber 8 by adding the spring pressure (2 bar) to the ambient pressure in the control port 7. In addition, the valve 5 is constantly flown through and thus its valve piston is kept moving, whereby pressure peaks are avoided and possible hysteresis effects are kept low.

(12) The circulating oil is again supplied to the transmission 1 via the return line 11. In an advantageous embodiment, this returning oil is used for lubricating transmission parts whose oil wetting is not ensured by the general operation.

(13) In another advantageous embodiment or in an extension of the function, heat exchangers, filters and devices for oil analysis can be integrated into the line 11 in order to dissipate heat, remove gear abrasion from the oil and reveal a decrease in the sealing effect, in particular by detecting components of the supporting liquid in the oil.

(14) In its basic configuration, the presented system can do without electronic components and without any further control effort. The sealing effect of the bearing seal is maintained even upon failure of all control systems as long as the drive unit of the entire system is in operation.

(15) In the embodiment of FIG. 2, which is slightly modified with respect to FIG. 1, the sealing chambers 8 are not hermetically sealed, but instead relieved into the transmission space 4 via throttles 13. Such a modification permits a dissipation of heat from the sealing chamber 8 and an oil exchange and oil purification of the sealing chamber 8. The remaining design of the embodiment of FIG. 2 is identical to FIG. 1, which is why identical reference numerals have been used.