EP3779209B1 - Self-propelled working machine on a solid floor surface with hydraulic unit mounted on a chassis - Google Patents

Description

The invention relates to a work machine that is self-propelled on a solid ground surface and has a hydraulic unit mounted on a chassis for operating the work machine by pumped hydraulic fluid as a power transmission means, the hydraulic unit consisting of a liquid tank provided for receiving the hydraulic fluid and at least one for removing it from the latter and returning the hydraulic fluid via a liquid return line of the hydraulic fluid into the liquid tank, preferably electrically driven feed pump, as well as a switching valve arrangement that can be controlled between the feed pump and at least one rotary and / or linearly driven consumer of the work machine, which are arranged on the liquid tank, the liquid tank being formed from a container that is open at the top is and the feed pump and the switching valve arrangement connected to it, the connecting lines of the unit components and a liquid filling opening are arranged as a unit on a closure plate that closes the container opening, the closure plate being formed from a metallic material, preferably from structural steel, and the container being formed in one piece.

In a hydraulic unit for an industrial truck according to what has become known DE 10 2004 032 256 B3 , the motor pump unit is attached directly/immediately to the tank via a tank opening, and the return filter, which has an elongated filter housing for a filter element with a filter cartridge, is inserted into a tank opening intended for it in the tank and has a hose connection and an outlet opening , wherein the filter element is arranged in the flow path between the hose connection and the outlet opening, and a return hose that connects the motor pump unit and the hose connection within the tank. This is intended to largely eliminate disadvantages in the event of leaks between the hydraulic unit and a return filter with external connections.

Liquid tanks made of metal, primarily structural steel, are known as hydraulic units and are formed by welding with feed pumps, valve blocks and filters as well as a filler neck.

In a mobile/mobile application, a built-up hydraulic unit with a sheet metal tank made of structural steel is relatively heavy and, with complex chassis and body shapes such as those formed on the outer contour of a vehicle, for example in the wheel arch area, very expensive to produce.

Furthermore, a welded liquid tank is susceptible to corrosion, particularly after damage to the surface, and stresses around the weld seams lead to leaks.

A plastic tank has a significant disadvantage when integrating attached aggregation components, such as motors, pumps and valve combinations, especially since the required fastening structures, for example insert frames, can only be implemented in narrow dimensions due to the different expansion coefficients of metal and plastic, because temperature fluctuations lead to a reduction in stability and loss of rigidity , lead to leaks between the insert frames and the plastic tank and weaken the existing strength.

WO 2017/005338 A1 discloses a hydraulic unit, the electric motor and the hydraulic pump of which are flanged to a first structural unit serving as a supporting device. The latter is formed by a metallic molded body which is accommodated in a seat which is formed in the top of a second structural unit formed by a plate-like plastic body. This forms a kind of tank cap for the upper open side of the tank of the hydraulic unit. The material of the tank is not specified.

WO 99/13229 A1 discloses an embodiment of a hydraulic unit in which the tank is open at the top and closed by a tank cap. The material of these two parts is not specified. In contrast, in a further embodiment, the tank is made in one piece from plastic with a connection opening for a housing part of the pump.

Likewise is in WO 2009/156017 A1 the tank made of plastic is formed in one piece, with the pump lines being connected through a circular pipe socket formed on the upper top wall of the tank.

DE 10 2016 101 662 A1 relates to a flow line for a pump device of a motor vehicle with flow elements arranged in the flow line. Also revealed US 6,116,454 A a hydraulic oil tank for a work machine with a flow guide element arranged in the tank.

From these disadvantages or Expectations in work use, the present invention has set itself the task of developing a hydraulic unit that has a high level of reliability in use, allows easy assembly when setting up the affected unit components and proves to be robust over a long period of use, and it is intended the susceptibility to wear and the risk of leakage can be largely eliminated.

According to the invention, the object was achieved in that the container is manufactured with plastic using the rotational molding or injection molding process and the container is box-shaped and has a container end shaped according to a section of a wheel arch of the mobile work machine.

The solution according to the invention is intended to provide the hydraulic unit with a high quality of functions and greater precision among the aggregation components as well as simple assembly of the unit components built on the closure plate. After pre-assembly on the closure plate, the unit components can be assembled away from the container and tested for function and then installed together on the closure plate of the liquid tank in the container or removed from it individually or together for maintenance and/or repair. The hydraulic fluid flowing back into the fluid tank after use is returned via a fluid return line, which is preferably provided with a return filter at the end.

Due to the necessary favorable accessibility, an outer wall of the container can form a supplementary part of the vehicle body (body part) of the work machine.

According to the invention, the closure plate, which also serves as a cover for the container, is made of a metallic material, preferably made of structural steel, for example a sheet steel or the like, for high stability of the hydraulic unit on the chassis of the work machine and provides a large-area, torsion-resistant connection to the liquid container.

Alternatively, it is possible that the upper end or The connecting end of the container to the closure plate is formed by a fastening device provided for sealing between the container and the closure plate.

To promote the strength and stability of the liquid tank and the container, the open edge of which can be reinforced for a tight connection to the attached closure plate.

The feed pump(s), which form a unit and form a unit, the switching valve arrangement, the liquid filter protruding into the liquid tank, the connecting lines and screw connections and other fittings as well as a liquid filler neck are advantageously attached to the closure plate and thus facilitate assembly and disassembly as a unit maintenance work and controls.

According to the invention, the container is designed in one piece, but also fulfills its relevant function and task in a two-part design.

If the multi-part design is not according to the invention, the container can also be made from plastic using a different process, which proves to be a durable material and resistant to corrosion and impact situations.

The liquid filling opening is preferably formed by a filling and venting filter which projects into the liquid-free space of the liquid tank and is attached to the underside of the closure plate.

The container is box-like and is equipped with a container end shaped like a section of a wheel arch of the mobile work machine, so that it can be attached to the chassis in a space- and weight-saving manner and is easily accessible from the outside.

It proves to be advantageous if the assembly components mentioned are each detachably attached to the closure plate, so that they can be replaced on the closure plate in individual cases.

A filling and venting filter is preferably arranged in the liquid tank above a certain liquid level so that it can optimally develop its effect.

It proves to be simple if the container below the feed pump(s) immersed in the liquid has a container constriction that connects the container into two container spaces, which protrudes from the bottom of the container upwards into the container and ends approximately below the aggregate components, whereby in the container spaces a mixing of the stored cooled liquid with the returned warmer liquid quantity can be achieved.

For this purpose, it is provided that the container constriction is formed by at least one flow threshold that distinguishes/divides the liquid tank into a liquid return flow and a container space assigned to the liquid suction, through which a laminar mixture of the returned and the resting hydraulic liquid is achieved.

The flow threshold(s) can be provided on a rear wall of a cavity placed in the container and thus promote a heat balancing effect.

A suction opening of the suction line connected to the feed pump(s) is advantageously arranged in the container space at a lower liquid temperature than in the other container space of the liquid tank.

Fig. 1

eine räumliche Darstellung eines Hydraulikaggregats einer erfindungsgemäßen selbstfahrenden Arbeitsmaschine,

Fig. 2

eine Schnittebene durch das in Fig. 1 dargestellte Hydraulikaggregat gemäß Linie II - II,

Fig. 3

eine Schnittebene durch das in Fig. 2 dargestellte Hydraulikaggregat gemäß Linie III - III.

The invention is explained below using an exemplary embodiment with reference to the cited or citing prior art and the drawing, to which reference is made with regard to all details not mentioned in more detail in the description. Show in the drawing:

Fig. 1

a spatial representation of a hydraulic unit of a self-propelled work machine according to the invention,

Fig. 2

a cutting plane through the in Fig. 1 hydraulic unit shown according to line II - II,

Fig. 3

a cutting plane through the in Fig. 2 Hydraulic unit shown according to line III - III.

Fig. 1 shows a spatially represented hydraulic unit 2 built on a chassis of a self-propelled work machine 1 for generating work force/performance by means of a circulating hydraulic fluid. For this purpose, the hydraulic unit 2 consists of a container 3 intended to hold the hydraulic fluid, made of plastic, for example made of fiber-crosslinked polyethylene, polyamide or similar material, which is produced in a rotational molding or injection molding process, advantageously in more complex shapes that are closer to the purpose, more cost-effective and with lower weight and appropriate rigidity compared to a tank made of welded steel sheets.

To remove hydraulic fluid from the container 3, at least one feed pump 11, 12 is provided, which is arranged inside the fluid tank and is screwed onto a preferably flat closure plate 6 which is fastened to the upper opening of the container 3 and forms a closed fluid tank 5. This serves to position and fasten the actuating elements or components of the hydraulic unit 2 as a furnishing unit and can be placed on the container edge 7 defining the upper opening of the container 3 and fastened to hold the liquid tank 5 tightly.

To fasten the closure plate 6 or connection plate or cover plate, screws 8 or comparable similar fastening elements are provided, which are anchored at the front in the container edge 7.

The feed pumps 11, 12, it could also be one, which are driven together by an electric motor 9, are screwed to the top of the closure plate 6 via a fastening flange provided on the electric motor and protrude hanging into the liquid tank 5 (see Fig.2 ).

Furthermore, they show Fig. 1 and 2 a switching valve arrangement 13 attached to the closure plate 6 for controlling the hydraulic fluid or of the unit components, and opposite, laterally offset from the electric motor of the feed pumps 11, 12, a filling and venting filter 14, which projects into the liquid tank 5 and is designed for filling the latter, and a service cover 15, respectively. closing flange, to which a return filter 20 which projects into the liquid tank 5 and is connected to the liquid return line 18 is attached.

Due to the components of the hydraulic unit 2 that are attached exclusively to the closure plate 6, this can be completely separated from the container 3 after the closure plate 6 has been released. be withdrawn.

The closure plate 6, which is made of a metallic material, for example structural steel, offers a high level of rigidity over the plate extension and, together with the container 3, exerts robust stability and rigidity on the liquid tank 5. In terms of manufacturing technology, the closure plate does not pose any high demands.

The flat extension/extension of the closure plate 6 allows a simple design and arrangement of the unit components, the construction of which can be carried out on the closure plate 6 using simple machine elements and work equipment.

The shape of the closure plate 6 is suitable for a tight connection with the container 3 at the container edge 7.

The unit components can be easily detached/removed from the locking plate 6 for maintenance, repair or replacement.

The container 3 is made in one piece and is manufactured with plastic using rotational molding or an injection molding process.

Not according to the invention, a container 3 made of sheet steel can also be used.

The container 3 is box-shaped so that it can be installed in a space-saving manner on/into the chassis 16 of the self-propelled machine and is easily accessible.

The container 3 of the liquid tank 5 is in the immediate vicinity of a wheel arch 17 of a rigid or a steerable front or rear axle of the mobile work machine 1, based on the geometry of the wheel arch shape. concentric to the wheel axis ( Fig. 2 ).

Like from the Fig. 1 and 2 As can be seen, the unit components 11, 12, 13, 14, 15 as well as the liquid lines of the system can be individually removed from the closure plate 6, be it for maintenance, repair or replacement.

As already mentioned, the return filter 20 is preferably part of the equipment of the hydraulic unit 2 and is attached to the closure plate 6 so that it projects into the liquid tank 5, the liquid return line 18, preferably at its end opening into the liquid tank 5, having an outlet opening, for example below the liquid level 19, is trained.

The return filter 20, equipped with a filter cartridge, is connected at the upper end to the liquid return line 18 (see Fig. 2 ).

The in Fig. 1 The illustrated service cover (flange) 15 for replacing or maintaining the return filter 20 lies above an invisible filling opening, which is usually extended by a filler neck projecting into the liquid tank 5.

Below a liquid level 19 or of the aggregate components projecting into the liquid tank 5, the liquid tank 5 is divided into two unseparated container spaces 22, 23 by a constriction provided in the container 3 by means of a threshold arrangement 21. This is in the Fig. 2 and 3 It can be seen that a lower wall part of the rear container wall 24 is offset towards the front wall 25 of the container 3 and extends to a height below the aggregate components or the liquid level 19, and thus forms a cavity 26.

The side walls 27, 28 and roof-like ceiling elements 29, 30 complete the cavity 26, on the back of which, container wall part 24, a pair of laterally spaced, strip-like flow thresholds 31, 32 protruding against the front container wall 25 are arranged. As a result, the hydraulic fluid flowing back from the working devices of the working machine 1 into the liquid tank 5 only flows to a small part of the container space 22 via the threshold device 31, 32 into the laterally adjacent container space 23 which is assigned to the suction line 34 of the feed pump (s) 11, 12. The larger part flows into the upper common area and mixes with the oil calmed in the liquid tank 5 and cools down slightly, with the suction opening 34 being arranged in the container space 23 with the lower liquid temperature. The flow thresholds 31, 32 are attached parallel to each other and running upwards on the back of the rear container wall 24.

Fig. 2 Additionally, it conveys the routing of the hydraulic fluid among the unit components and the consumers (not shown). The already mentioned suction line 34 carries the hydraulic fluid by means of feed pumps 11, 12 separately through the pressure lines 36, 37 via the controllable switching valve arrangement 13 to the consumers or working devices of the work machine 1 and from there via the switching valve arrangement 13 and liquid return line 18 and return filter 20 into the container space 22 respectively. the liquid tank 5.

Claims (14)

1. A machine (1) that is self-propelled on a solid ground surface, comprising a hydraulic unit (2) built on a chassis (16) for operating the machine (1) using a pumped hydraulic fluid as a power transmission medium, wherein the hydraulic unit (2) consists of: a fluid tank (5) provided for receiving the hydraulic fluid, and at least one connected feed pump (11, 12), preferably electrically driven, for withdrawing the hydraulic fluid therefrom and returning it via a fluid return line (18) to the fluid tank (5), as well as a switching valve arrangement (13) controllable between the feed pump (11, 12) and at least one rotationally and/or linearly driven consumer of the machine (1), which are arranged on the fluid tank (5), wherein the fluid tank (5) is formed from a container (3) which is open at the top, and wherein the feed pump (11, 12), the switching valve arrangement (13) connected to it by means of a line, the connecting lines of the hydraulic unit components and a fluid filling opening (15) are arranged as a unit on a closure plate (6) which closes the container opening, wherein the closure plate (6) is formed from a metallic material, preferably from structural steel and the container (3) is formed as a single piece, characterised in that the container (3) is manufactured from plastic using the rotary moulding or injection moulding process and the container (3) is box-shaped and has a container end shaped according to a partial section of a wheel housing of the propelled machine (1).
2. The machine according to claim 1, characterised in that the upper end of the container (3) has a container edge (7) designed for a tight connection between the closure plate (6) and the container (3).
3. The machine according to claim 1 or 2, characterised in that the unit components (4, 11, 12, 13, 14, 15, 18, 34, 36, 37) are attached to the closure plate (6).
4. The machine according to one of the preceding claims, characterised in that the end of the container facing the wheel housing is arranged on the chassis (16) approximately concentrically to the affected wheel of the machine (1).
5. The machine according to one of claims 1 to 4, characterised in that the fluid filling opening (15) is formed though a filling and venting filter (14) protruding into the fluid-free space of the fluid tank (5).
6. The machine according to one of the preceding claims 1 to 5, characterised in that each of the unit components is detachably attached to the closure plate (6).
7. The machine according to claim 5, characterised in that the filling and venting filter (14) in the fluid tank (5) is arranged above a fluid level (19) of the hydraulic fluid in the hydraulic fluid tank (5).
8. The machine according to one of claims 1 to 7, characterised in that the fluid return line (18) ends in a reverse-flow filter (20).
9. The machine according to claim 8, characterised in that the reverse-flow filter (20) is attached to a flange-like cover (15) which closes a service opening on the closure plate (6).
10. The machine according to one of claims 1 to 9, characterised in that the container (3) has, underneath the feed pump (11, 12) which is submerged in the fluid, a container constriction (33) connecting the container (3) in two container spaces (22, 23), extends from the bottom of the container up into the container (3) and ends approximately below the unit components.
11. The machine according to claim 10, characterised in that the container constriction (33) is formed by at least one flow threshold (31, 32) which differentiates the fluid tank (5) into two container spaces (22, 23): one of which is assigned to fluid return and the other of which is assigned to fluid consumption.
12. The machine according to claim 11, characterised in that the flow threshold (31, 32) is provided on a rear wall of the cavity (26) protruding into the container (3).
13. The machine according to claims 10 to 12, characterised in that a suction opening (35) of a suction line (34) connected to the feed pump (11, 12) is arranged in the container space (23) having a lower fluid temperature.
14. The machine according to claims 10 to 13, characterised in that fluid lines (18, 35, 36) connecting the components of the hydraulic unit (2) are suspended on the underside of the closure plate (6).

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