EP2463227B1 - Hydraulic tank for an industrial truck - Google Patents

Description

The present invention relates generally to a hydraulic tank for an industrial truck.

In particular, the invention is based on a hydraulic tank for an industrial truck according to the preamble of claim 1.

To lift and lower loads, trucks have a hydraulic power pack with an associated hydraulic tank. The hydraulic power unit typically consists of a drive motor, usually an electric motor, and a pump operated by the drive motor, which draws hydraulic medium (hydraulic oil) from the hydraulic tank via a suction port of the hydraulic tank. For lifting loads, for example, a single-acting lifting cylinder is actuated via the hydraulic unit, wherein, for example, a check valve may be provided in the hydraulic unit to hold the load on the hydraulic cylinder. If the truck is used to lower a load, the hydraulic medium flows back into the hydraulic tank via a return line and a return connection of the hydraulic tank. Typically, the return of the hydraulic medium (hydraulic oil) via a return filter unit. The hydraulic unit can also supply other functional components of the truck with hydraulic fluid under pressure, for example a steering device.

From the DE 10 2005 035 845 A1 an oil container made of plastic is known, which consists of at least two interconnected sub-housings and on the inside and / or outside of at least one of the sub-housing integrally formed stiffening ribs.

From the DE 196 12 582 A1 is a drive unit for a vehicle with an electric motor and a hydraulic pump known, which are housed together for silencing and / or for simultaneous achievement of improved explosion protection in the hydraulic tank.

An object of the invention is to provide a hydraulic tank of the type mentioned, which can be produced inexpensively.

Another object of the invention is to provide a hydraulic tank of the type mentioned, which can be mounted in a truck and put into an operational state without great installation effort.

To solve at least one of these objects, the invention proposes a hydraulic tank with the features of claim 1.

According to the invention, the upper tank part and thus the hydraulic tank on the hydraulic medium intake pipe and the hydraulic medium return pipe as integral components, so that they must not be retrofitted. The hydraulic tank is thus provided in a ready-to-install state, and also the hydraulic medium suction pipe and the hydraulic medium return pipe together with the associated hydraulic medium suction port and hydraulic medium return port are provided. The production of this hydraulic tank is inexpensive possible, since the joining takes place on the basis of a tank lid, the hydraulic medium intake pipe and the hydraulic medium return pipe comprehensive tank top part, which is assembled as a unit with the tank bottom to the hydraulic tank. Preferably, a welding of the tank lid with the upper edge of the side wall, whereby especially (but not exclusively) is thought of a laser welding.

Manufacturing advantages, in particular with regard to the saving of manufacturing costs, are achieved in particular when of the hydraulic medium intake pipe and the hydraulic medium return pipe at least one is made in one piece with the tank lid, preferably in an injection molding process.

At least one of the hydraulic medium suction pipe and the hydraulic medium return pipe may be inclined with respect to a vertical axis of the hydraulic tank. If the hydraulic tank is produced in an injection molding process in which the vertical axis corresponds to the removal direction of the injection molding tool, it is preferred that such a pipe running obliquely with respect to the vertical axis is not produced in one piece with the tank lid, but is produced separately and then joined to the cover, for example, welded or glued to this. However, such a configuration is not only of interest for a sloping pipe. It is therefore generally proposed that of the hydraulic medium intake pipe and the hydraulic medium return pipe at least one, preferably the opposite to the vertical axis oblique pipe, welded or glued to the lid.

Conveniently, at least one of the hydraulic medium suction pipe and the hydraulic medium return pipe, preferably the hydraulic medium suction pipe, may extend in the direction of the vertical axis of the hydraulic tank. Regarding such a pipe, it is especially thought that this is made in one piece with the tank cap, preferably in an injection molding process. The vertical axis can then suitably correspond to the Entformungsrichtung of the injection mold.

The hydraulic medium suction port is preferably made in one piece with the hydraulic medium intake pipe and / or with the lid. The hydraulic medium return connection is preferably made in one piece with the hydraulic medium return pipe and / or with the cover.

1. a) wenigstens einer vorzugsweise einteilig mit dem Deckel hergestellten Halterungsformation an einer Deckelaußenseite zur Halterung des Tanks in dem Flurförderzeug,
2. b) wenigstens einem vorzugsweise einteilig mit dem Deckel hergestellten Luftfilteranschluss, der vorzugsweise ein Schraubgewinde zur Verschraubung mit einem Luftfilter aufweist,
3. c) wenigstens einer vorzugsweise einteilig mit dem Deckel hergestellten Eingriffsformation an einer Deckelinnenseite zum Eingriff mit einem zur Tankversteifung oder/und als Schwallschutz in der Hydraulikmedium-Aufnahmekammer vorgesehenen, sich zwischen einem vorderen und einem hinteren Wandungsabschnitt der Wandung erstreckenden Zwischenelement,
4. d) wenigstens einer vorzugsweise einteilig mit dem Deckel hergestellten, sich zwischen einem vorderen und einer hinteren Wandungsabschnitt der Wandung erstreckenden Zwischenelement an einer Deckelinnenseite, welches zur Tankversteifung oder/und als Schwallschutz in der Hydraulikmedium-Aufnahmekammer vorgesehen ist,
5. e) wenigstens einer vorzugsweise einteilig mit dem Deckel hergestellten Halterungsformation an einer Deckelaußenseite zur Halterung einer Hydraulikleitung oder einer anderen dem Hydrauliktank räumlich zugeordneten oder zuzuordnenden Komponente.

It is further thought that the lid is executed with at least one of

1. a) at least one support formation, preferably made in one piece with the cover, on a cover outside for holding the tank in the industrial truck,
2. b) at least one air filter connection, preferably made in one piece with the cover, which preferably has a screw thread for screwing to an air filter,
3. c) at least one engagement formation, preferably produced integrally with the cover, on an inner side of the cover for engagement with an intermediate element provided between a front and a rear wall section of the wall for tank stiffening and / or as splash protection in the hydraulic medium receiving chamber,
4. d) at least one preferably integrally formed with the lid, extending between a front and a rear wall portion of the wall intermediate member on an inner side lid, which is provided for tank stiffening and / or as surge protection in the hydraulic medium receiving chamber,
5. e) at least one preferably integrally formed with the cover mounting formation on a lid outer side for holding a hydraulic line or other the hydraulic tank spatially assigned or attributable component.

The mentioned design options c) and d) are not mandatory, but are typically regarded as alternatives. The one-piece production with the lid, the otherwise necessary assembly of separate components is saved, resulting in significant cost advantages.

As regards the tank bottom, a front and a rear wall section is defined by at least one extending therebetween, preferably as at least one hydraulic medium passage having connecting or releasing partition connected intermediate element, which serves as surge protection and / or as tank stiffening. A hydraulic medium splash guard (oil splash guard) and a tank stiffening is usually required because the hydraulic tank is arranged in a moving, to be accelerated and braked and curves to be controlled truck, so that the hydraulic medium is subjected to corresponding inertial forces that support and for which the resulting medium displacements are to be limited. Furthermore, during operation of the truck or the hydraulic unit, a certain negative pressure or overpressure in the tank may arise, which could lead to deformations of the tank walls, which counteracts the proposed tank stiffening.

The intermediate element is in the front and the rear wall portion in each case with a one-piece, preferably in an injection molding, produced with the side wall mounting formation of the front and rear wall section in positive engagement. By means of the intermediate element and the positive engagement with the support formations both tensile forces and compressive forces between the front and the rear wall portion are transferable.

If not only compressive forces but also tensile forces can be transmitted between the front and the rear wall section, deformation of the tank walls can be counteracted to a sufficient extent as a result of inertial forces acting on the hydraulic medium or due to overpressures in the tank.

Suitably, a plurality of such intermediate elements can be provided, which are arranged in a horizontal direction of a horizontal main direction of the tank corresponding transverse direction of the tank at a distance from each other and divide it into preferably communicating sections.

The attachment formations of the front and of the rear wall section are designed as support webs extending in the direction of a vertical axis of the hydraulic tank on the inside of the wall, each of which extends in the direction of the vertical axis Holding recess which widens, starting from a feedthrough slot in the transverse direction, to engage with a substantially complementary shaped support edge of the intermediate element to form the Formschlusseingriffs. The form-fitting engagement can be executed in the manner of a dovetail joint. The vertical axis corresponds - as mentioned - preferably the Entformungsrichtung of the tool in the manufacture of the lower tank part by injection molding.

The intermediate element or the plurality of intermediate elements are each inserted with their support edges in the support recess of the two associated support webs in the direction of the vertical axis, preferably until they abut on a desired case offset from the bottom upwards stop.

If the hydraulic tank has a pipe running obliquely with respect to the vertical axis of the hydraulic tank, then this can expediently be held or supported by means of an intermediate element connecting the front and the rear wall section. Specifically, it is proposed that the pipe inclined from the vertical axis of the hydraulic tank is supported by the hydraulic medium suction pipe and the hydraulic medium return pipe at a lower end portion through an intermediate member connecting the front and rear wall portions, the end portion preferably being formed by a recess extends the intermediate element and is preferably welded or glued thereto.

The intermediate element is an intermediate element as mentioned above, which serves as surge protection and / or as tank reinforcement. But it may also be an optionally opposite to such an intermediate element additional, serving primarily for pipe support intermediate element. Also in the latter case, the positive attitude of the intermediate element offers by holding webs with postural recesses and execution of the intermediate element with substantially complementary shaped retaining edges to be particularly useful.

1. a) wenigstens einer vorzugsweise einteilig mit dem Tankunterteil hergestellten Halterungsformation an einer Außenseite der Wandung oder/und an einer Außenseite des Bodens zur Halterung des Tanks in dem Flurförderzeug,
2. b) wenigstens einem vorzugsweise einteilig mit dem Tankunterteil in dessen Boden hergestellten Hydraulikmediumauslass, der vorzugsweise ein Schraubgewinde zur Verschließen mit einem einschraubbaren Verschlusselement aufweist,
3. c) wenigstens einer vorzugsweise einteilig mit dem Tankunterteil hergestellten Halterungsformation an einer Innenseite des Bodens zur Halterung eines unteren Endabschnitts eines zugeordneten von dem Hydraulikmedium-Ansaugrohr und dem Hydraulikmedium-Rücklaufrohr,
4. d) wenigstens einem vorzugsweise einteilig mit dem Tankunterteil hergestellten weiteren Hydraulikmedium-Rücklaufanschluss,
5. e) wenigstens einer Minimum-Markierung und wenigstens einer Maximum-Markierung an einer Außenseite der Wandung zur Kennzeichnung wenigstens eines vorgesehenen minimalen und wenigstens eines vorgesehenen maximalen Füllstands des Hydraulikmediums in Hydraulikmedium-Aufnahmekammer, wobei die Markierungen vorzugsweise einteilig mit dem Tankunterteil hergestellt sind,
6. f) wenigstens einer vorzugsweise einteilig mit dem Tankunterteil hergestellten Halterungsformation an einer Außenseite der Wandung zur Halterung einer Hydraulikleitung oder einer anderen dem Hydrauliktank räumlich zugeordneten oder zuzuordnenden Komponente.

Concerning the tank bottom, it is further contemplated that this is done with at least one of

1. a) at least one support formation, preferably made in one piece with the tank bottom, on an outer side of the wall and / or on an outer side of the floor for holding the tank in the industrial truck,
2. b) at least one Hydraulikmediumauslass preferably made in one piece with the tank bottom in the bottom, which preferably has a screw thread for closing with a screw-fastener,
3. c) at least one support formation, preferably made in one piece with the tank bottom part, on an inner side of the bottom for holding a lower end portion of an associated one of the hydraulic medium intake pipe and the hydraulic medium return pipe,
4. d) at least one further preferably made in one piece with the tank bottom further hydraulic medium return port,
5. e) at least one minimum marking and at least one maximum marking on an outer side of the wall for identifying at least one intended minimum and at least one intended maximum level of the hydraulic medium in the hydraulic medium receiving chamber, wherein the markings are preferably made in one piece with the tank bottom are,
6. f) at least one preferably integrally formed with the tank bottom bracket assembly on an outer side of the wall for holding a hydraulic line or other the hydraulic tank spatially assigned or attributable component.

By a one-piece production with the lower tank part, the separate installation of corresponding separately produced components is saved.

At least the tank lid and the tank bottom part are preferably made of a thermoplastic material, preferably a polyamide, of the hydraulic tank. It is especially thought of a polyamide such as PA6 or PA12. It is also polypropylene as a material for the production of said tank components in question.

The hydraulic tank can be made entirely of plastic material with all the associated components mentioned and contain no metal parts. However, it should not be excluded that in connection with certain components or functions metallic sub-components are molded into the plastic material, for example, fasteners that are part of one of the mentioned support formations.

The invention further provides an industrial truck, which is designed with a hydraulic tank according to the invention associated with at least one hydraulic unit of the industrial truck. The hydraulic tank is preferably fastened by means of mounting formations of the hydraulic tank to a frame of the truck. The hydraulic tank may have a space-saving arrangement of the hydraulic tank, the hydraulic unit and other components of the truck enabling adapted shape, for example, one or more indentations to allow the positioning of other components in the immediate Neighborhood of the tank while good use of the available space.

The invention further provides a method of manufacturing a hydraulic tank according to claim 10.

Advantageous developments of the method will become apparent from the foregoing training proposals to the hydraulic tank according to the invention.

Fig. 1

zeigt einen einbaufertig hergestellten Hydrauliktank nach einem bevorzugten Ausführungsbeispiel in einer "transparenten" oder geschnittenen Darstellung.

Fig. 2

zeigt ein einen Tankdeckel, ein Ansaugrohr und ein Rücklaufrohr umfassendes Tankoberteil, welches fertiggestellt ist, um mit einem zugeordneten Tankunterteil zusammengefügt zu werden, um den Hydrauliktank gemäß Fig. 1 zu bilden.

Fig. 3

zeigt das zum Tankoberteil gemäß Fig. 2 zugeordnete Tankunterteil, welches einen Boden und eine Seitenwandung aufweist, die im mit dem Tankoberteil zusammengefügten Zustand zusammen mit dem Tankdeckel eine Aufnahmekammer begrenzen.

Fig. 4

zeigt das Tankunterteil der Fig. 3 in einer anderen Darstellung mit Sicht auf den Tankboden.

Fig. 5

zeigt das Tankunterteil in einer anderen Darstellung mit Sicht in den vom Tankboden und der Seitenwandung begrenzten Innenraum.

Fig. 6

zeigt das Tankunterteil in einer weiteren anderen Ansicht.

Fig. 7

zeigt eines von mehreren trennwandartigen Zwischenelementen, die im Innenraum des Tankunterteils angeordnet sind und als Schwappschutz und zur Versteifung dienen.

Fig. 8

zeigt ein Paar von stegartigen Halterungsformationen an der Innenseite eines vorderen und eines hinteren Randabschnitts des Tankunterteils zur formschlüssigen Halterung eines Zwischenelements wie in Fig. 7 gezeigt.

Fig. 9

zeigt das Zwischenelement der Fig. 7 in einer anderen Ansicht mit Sichtrichtung in einer Haupterstreckungsrichtung.

Fig. 10

zeigt das Tankoberteil der Fig. 2 in einer anderen Ansicht.

Fig. 11

zeigt den fertig hergestellten Hydrauliktank 10 in einer seitlichen Ansicht auf eine vordere Tankwand und eine Seitenwand.

The invention will be explained in more detail below with reference to an embodiment shown in FIGS.

Fig. 1

shows a ready-made hydraulic tank according to a preferred embodiment in a "transparent" or cut representation.

Fig. 2

shows a tank top, a suction pipe and a return pipe comprehensive tank top, which is completed to be mated with an associated tank bottom to the hydraulic tank according to Fig. 1 to build.

Fig. 3

shows that to the tank top according to Fig. 2 associated tank bottom part, which has a bottom and a side wall, which limit together with the gas cap in the tank top part together with the tank lid a receiving chamber.

Fig. 4

shows the tank bottom of the Fig. 3 in a different view with a view of the tank bottom.

Fig. 5

shows the bottom tank part in another view with a view of the tank bottom and the side wall limited Inner space.

Fig. 6

shows the lower part of the tank in another different view.

Fig. 7

shows one of several partition wall-like intermediate elements, which are arranged in the interior of the tank bottom and serve as Schwappschutz and for stiffening.

Fig. 8

shows a pair of web-like support formations on the inside of a front and a rear edge portion of the tank bottom for the positive retention of an intermediate element as in Fig. 7 shown.

Fig. 9

shows the intermediate element of Fig. 7 in another view with view in a main direction of extension.

Fig. 10

shows the tank top of the Fig. 2 in a different view.

Fig. 11

shows the finished hydraulic tank 10 in a side view of a front tank wall and a side wall.

Fig. 1 shows a hydraulic tank 10 according to the invention according to a preferred embodiment. The tank is shown in a transparent or cut-away perspective view, which is essentially a section along the inside of a in Fig. 6 corresponds to the rear tank wall 12 shown in plan view on the outside. In an upper area of the hydraulic tank, this section corresponds to a section in the through Fig. 1 by a coordinate system marked level.

The hydraulic tank comprises a tank bottom part 14 which comprises a tank bottom 16 and a side wall 17, which of the already mentioned rear tank wall 12, one of these opposite front tank wall 18 and two in a transverse direction through the Tank walls 12 and 18 defined front-back direction opposite side walls 20 and 22 is formed.

The lower tank part may advantageously be produced in one piece in an injection molding process from a thermoplastic plastic material, for example polyamide, using an injection molding tool whose removal direction corresponds to a vertical axis of the lower tank part.

One to the in the Fig. 3 to 6 and 8th shown tank bottom part 14 associated tank top 30 is in Fig. 2 shown. The upper tank part 30 comprises a lid 32 which, together with the side wall 17 and the tank bottom 16, delimits a hydraulic medium receiving chamber of the hydraulic tank 10. In the finished state of the tank according to Fig. 1 the upper tank part 30 is joined to the lower tank part 14, preferably by welding, preferably laser welding. Conveniently, the contact surface between the tank lid and the side wall can be welded, so that the laser has to drive only a two-dimensional contour of the tank circumference and does not have to be adjusted in height.

The tank upper part 30 comprises, in addition to the tank lid 32, a hydraulic medium intake pipe 34 which projects with an upper end portion over an upper side of the tank lid 32, which serves as a hydraulic medium suction port 36, via which a hydraulic unit connected suck hydraulic medium (preferably hydraulic oil) from the hydraulic tank 10 can. Preferably, the intake pipe 34 is made in one piece with the tank lid 32. This preparation may conveniently be effected by means of an injection molding process, using a thermoplastic plastic material, for example polyamide. Appropriately, the Entformungsrichtung of the injection mold of a vertical axis of the tank top 30 may correspond, in the direction of which the intake pipe 34 corresponds. In the assembled state of Fig. 1 can the vertical axis of the tank top 30 and the vertical axis of the Tank bottom parts 14 coincide.

The tank upper part 30 further comprises a partially obliquely opposite to the vertical axis extending hydraulic medium return pipe 38, which protrudes with an upper end portion of an upper surface of the tank lid 32, which serves as a hydraulic medium return port 40. About this return port can be returned in hydraulic operation of the hydraulic unit in the hydraulic tank 10 attributable hydraulic medium in the hydraulic tank. Depending on the intended manufacturing process, it is also advisable to produce the return pipe 38 in one piece with the tank cap 32 or to produce the return pipe 38 separately and then to assemble it with the tank cap 32. Preferred in connection with the production of the tank top part in an injection molding process is a separate production of the return pipe 38 from a preferably identical plastic material. The return pipe 38 can then be inserted into a designated opening in the tank lid 32 and connected to this fixed and hydraulic medium tight, for example by welding or gluing. In this way, that will be in the Fig. 2 and 10 illustrated tank top 30 is provided as a structural unit, which can be assembled as a unit with the tank bottom part 14.

Suitably, the tank top 30 and the tank lid 32 and the tank bottom 14 may be equipped with one-piece further functional elements produced therewith, resulting directly from a corresponding shape of the mold used in the production, in particular injection mold.

Thus, the tank lid 32 integrally with him associated support formations or fasteners 42 and 44 on the top cover, which are used for secure attachment of the hydraulic tank in a truck to the body frame. Further, the tank lid 32 has a longitudinally elongated cuboidal configuration 46, which is designed with an air filter port 48, the advantageous one can have one piece molded Einschraubgewinde for the air filter.

For arranging and fastening at least one further component, for example one or more hydraulic lines, the lid 32 in the region of the box-like configuration 46 further has a recess 50 and a screw-in opening 52, which extends into a projection 54 on the underside of the lid to a sufficient length to provide for the inclusion of a screw here fastener. It will open Fig. 10 directed. Another such approach with screw on the top is designated 56 and 58.

Furthermore, the lid 32 has on its underside a plurality of supports 60, 62 and 64 which engage positively with respect to the tank bottom part 14 and the tank top 30 separate intermediate elements, which serve for tank stiffening and as Schwappschutz and of which one in the Fig. 7 and 9 is shown. According to Fig. 1 a plurality of such intermediate elements are arranged in the tank bottom part 14.

All the above-mentioned functional elements are integral with the lid 32.

Correspondingly, the lower tank part 14 also has molded-on or integrally produced configurations and functional elements. Thus, on the tank bottom 16 on the outside projecting mounting formations 70 and 72 for storage and mounting of the tank in the truck realized (see. Fig. 4 ). Furthermore, in the tank bottom 16, a drain arrangement 74 is implemented, which serves for draining the hydraulic medium (hydraulic oil) located in the receiving chamber of the tank and comprises a threaded hole for a drain plug. On the bottom inside of the support formation 72, a support assembly 76 is realized in the region of the support, which engages positively with the lower end of the suction pipe 34 and the suction tube 34 secures against vibrations arising during operation. Further, at the rear tank wall 12th and at the front tank wall 18 on the inside of retaining webs integrally formed with the tank wall in question, which serve for the positive retention of the already mentioned intermediate elements and production of a train and pressure resilient support connection between the front and the rear tank wall. These brackets are in Fig. 5 designated 78a, 80a and 82a and 78b, 80b and 82b. All of these addressed embodiments of the lower tank part 14 are made in one piece with this. The support webs extend in the direction of the vertical axis of the tank bottom part. Fig. 8 shows a pair of mutually associated support webs, for example, the webs 80a and 80b, on the front and the rear tank wall in an enlarged view according to another viewing direction.

In addition, minimum and maximum markings for the filling level of the hydraulic medium in the tank may also be integrally formed in one piece into the outside of the tank side wall, as in FIGS Fig. 3 . 4 and 11 to recognize.

Advantageously, the hydraulic tank 10 and especially its lower part 14 have such a shape, which allow a space-saving compact arrangement of the hydraulic tank 10 together with adjacent to this to be arranged components such as hydraulic unit and engine of the truck. Thus, the front tank wall 18 has a recess 90 in a lower region and, in a region adjoining the side wall 22, a bulge 92 almost over the entire height (cf. Fig. 3 . 4 and 5 ). The side walls 20 and 22 extend in the vertical direction in a certain way, in view of the arrangement of the tank in the truck (see. Fig. 1 . 4 and 11 ).

According to Fig. 1 are three intermediate elements 94a, 94b and 94c received in the tank and held by a respective support web pair 78a, 78b and 80a, 80b and 82a, 82b positively. For this purpose, the webs in vertically extending mounting recesses or grooves 96a and 96b, respectively, which receive transverse to a wall-like portion 98 of the respective support member projecting, substantially complementary to the recess running support edges 100a and 100b of the respective support member. It will open Fig. 7 . 8 and 9 directed. In the in the Fig. 7 and 9 The intermediate element shown may be the intermediate element 94b, which engages positively with the webs 80a, 80b.

As in Fig. 1 can be seen, the tank interior is divided by the intermediate elements in sections, but communicate because of remaining free passages below the respective intermediate element with each other, so that the hydraulic medium can flow from section to section. For securing a hydraulic medium passage, the intermediate elements may have, for example, a recess at a lower edge, as in FIGS Fig. 1 and 7 to recognize. Alternatively or additionally, through holes may also be formed in the intermediate elements.

The intermediate elements are respectively inserted before the joining of the upper tank part with the tank bottom part from above into the retaining recesses of the respective support web pair, preferably so far, until they abut against a stop formed by a lower end of the groove-like retaining recess. This stop can be offset relative to the tank bottom 16 up to ensure the necessary hydraulic flow between the tank sections. When joining the upper tank part 30 with the lower tank part 14, the upper edges of the intermediate elements engage in a retaining slot of a respective associated one of the supports 60, 62 and 64 on the underside of the cover. For this purpose, the supports have a respectively adapted length, so that on the one hand the respective intermediate element is secured in a stop position abutting the stop and on the other hand, the lid is supported by means of the intermediate element.

The described embodiment of the intermediate elements and the support webs is such that both tensile forces and compressive forces between the front and the rear tank wall are transmitted and thus the tank is given a high stability.

As mentioned, the intake pipe 34 is preferably secured at the lower end against vibrations, for example by the mentioned support assembly 76 on the tank bottom. Also with respect to the inclined return pipe 38, it is advisable to provide a safeguard against vibration which holds the return pipe at a lower end portion. The in Fig. 1 . 2 and 10 is based on a preferred implementation in this respect.

The return pipe 38 is made or provided at a lower end with an intermediate member 110 which, like the intermediate members 94a, 94b and 94c, is formed with support edges, for example, similar or identical to the support edges 100a and 100b provided in associated support recesses of support webs on the inner sides of the support legs front and rear tank wall engage positively. Separate retaining webs may be provided for holding the intermediate element 110 relative to the mounting webs 80a and 80b, or the mounting of the intermediate element 110 may likewise be effected by means of the mounting webs 80a, 80b for the intermediate element 94b. In the latter case, the intermediate element 94b does not abut on a stop corresponding to one end of the retaining recess, but is already at the lower tube end of the return pipe 38 of the tank upper part, before the tank top part 30 is joined to the tank bottom part 14 between the support 62 and the upper end of the intermediate element 110 30 and then insert together with the intermediate member 110 in assembling the tank top with the tank bottom with the support edges in the support recess 96 a and 96 b. In deviation from the explanation given above, in this case only the intermediate elements 94a and 94c are in advance in the tank bottom part 14 whereas the intermediate member 94b together with the tank top 30 is to be assembled with the tank bottom 14.

The intermediate element 110 can, as in the Fig. 1 . 2 and 10 indicated, having an opening through which the lower end of the return pipe 38 extends. Preferably, the intermediate element 110 is glued or welded to the return pipe 38. Also, the intermediate element 110 can serve the stiffening of the tank and act together with the intermediate element 94b as Schwappschutz.

As already mentioned, a hydraulic medium from the hydraulic tank-related hydraulic unit can also supply other hydraulic consumers and hydraulically operated functional elements of the industrial truck with pressurized hydraulic medium. The hydraulic tank can therefore have one or more additional return connections, which can be carried out in the tank lid or in the tank bottom. The Fig. 3 . 4 and 11 show such an additional return port 120, which may be integral with the lower part 14 or subsequently inserted into a designated opening of the lower tank part 14 and preferably glued or welded to the tank bottom. The return port 120 may serve, for example, as a return from a steering of the truck.

Modifications and additions of the hydraulic tank according to the illustrated embodiment are readily possible, depending on the requirements and installation situations in a truck.

Claims (11)

1. Hydraulic tank (10) for an industrial truck, comprising:

   - a tank lower part (14) comprising a base (16) and a side wall (17) and produced in one piece,

   - a tank cover (32) which is connected to an upper edge of the side wall (17), is produced in one piece and defines at least one hydraulic-medium receiving chamber together with the base (16) and the side wall (17),

   - at least one hydraulic-medium intake pipe (34) extending from a hydraulic-medium intake connector (36) of the tank cover (32), preferably into a lower region of the hydraulic-medium receiving chamber,

   - at least one hydraulic-medium return pipe (38) extending from a hydraulic-medium return connector (40) of the tank cover (32), preferably into a lower region of the hydraulic-medium receiving chamber, the hydraulic-medium intake pipe (34) and the hydraulic-medium return pipe (38), together with the tank cover (32), forming a tank upper part (30) which is assembled as a modular unit together with the tank lower part (14) to form the hydraulic tank (10),

   characterised in that a front (18) and a rear (12) wall portion are connected by at least one intermediate element (94a, 94b, 94c) which extends between said wall portions and is preferably in the form of a partition which is open or comprises at least one hydraulic-medium passage, which intermediate element acts as a baffle and/or as tank reinforcement, each intermediate element (94a, 94b, 94c) on the front (18) and the rear (12) wall portion engages in an interlocking manner with a holding structure (78a and 78b; 80a and 80b; 82a and 82b) of the front and rear wall portion, which holding structure is produced, preferably in an injection-moulding process, in one piece together with the side wall,
   it being possible to transfer both tensile forces and compressive forces between the front (18) and the rear (12) wall portion by means of the intermediate element and the interlocking engagement with the holding structures (78a, 78b; 80a, 80b; 82a, 82b),
   and the holding structures of the front (18) and the rear (12) wall portion being formed as holding connecting pieces (78a, 78b; 80a, 80b; 82a, 82b) on the inside of the wall and extending in the direction of a vertical axis of the hydraulic tank, each of which connecting pieces comprises a holding aperture (96a; 96b) which extends in the direction of the vertical axis and, proceeding from a guide-through slot, widens in the transverse direction in order to engage with a holding edge (100a; 100b), formed in a substantially complementary manner, of the intermediate element (94a, 94b, 94c) in order to form the interlocking engagement.
2. Hydraulic tank according to claim 1, characterised in that at least one (34) of the hydraulic-medium intake pipe (34) and the hydraulic-medium return pipe (38) is produced in one piece together with the tank cover (32), preferably in an injection-moulding process.
3. Hydraulic tank according to either claim 1 or claim 2, characterised in that at least one (38) of the hydraulic-medium intake pipe (34) and the hydraulic-medium return pipe (38) extends obliquely relative to a vertical axis of the hydraulic tank.
4. Hydraulic tank according to any of claims 1 to 3, characterised in that at least one of the hydraulic-medium intake pipe (34) and the hydraulic-medium return pipe (38), preferably the pipe (38) extending obliquely relative to the vertical axis, is welded or adhesively bonded to the cover (32).
5. Hydraulic tank according to any of claims 1 to 4, characterised in that the cover (32) is formed having at least one of:

   a) at least one holding structure (42, 44), which is produced preferably in one piece together with the cover (32), on a cover outer face for holding the tank in the industrial truck;

   b) at least one air filter connector (48), which is produced preferably in one piece together with the cover and preferably comprises a screw thread for screwing to an air filter;

   c) at least one engagement structure (60, 62, 64), which is produced preferably in one piece together with the cover, on a cover inner face for engagement with an intermediate element (94a; 94b; 94c) which is provided for tank reinforcement and/or as a baffle in the hydraulic-medium receiving chamber and extends between a front (18) and a rear (12) wall portion of the wall (17),

   d) at least one intermediate element, on a cover inner face, which is produced preferably in one piece together with the cover, extends between a front and a rear wall portion of the wall, and is provided in the hydraulic-medium receiving chamber for tank reinforcement and/or as a baffle;

   e) at least one holding structure (54, 56, 50), on a cover outer face, which is produced preferably in one piece together with the cover for holding a hydraulic line or another component associated or to be associated spatially with the hydraulic tank.
6. Hydraulic tank according to any of claims 1 to 5, characterised in that the pipe (38), extending obliquely relative to the vertical axis of the hydraulic tank, of the hydraulic-medium intake pipe (34) and the hydraulic-medium return pipe (38) is held at a lower end portion by an intermediate element (110) connecting the front (18) and the rear (12) wall portions, the end portion preferably extending through an aperture in the intermediate element (110) and preferably being welded or adhesively bonded thereto.
7. Hydraulic tank according to any of claims 1 to 4, characterised in that the tank lower part (14) is formed having at least one of:

   a) at least one holding structure (70, 72), produced preferably in one piece together with the tank lower part, on an outer face of the wall and/or on an outer face of the base (16) for holding the tank in the industrial truck,

   b) at least one hydraulic-medium outlet (74) which is produced preferably in one piece together with the tank lower part in the base (16) thereof and preferably comprises a screw thread for closure by means of a closure element which can be screwed in,

   c) at least one holding structure (76), produced preferably in one piece together with the tank lower part, on an inner face of the base (16) for holding a lower end portion of an associated one of the hydraulic-medium intake pipe and the hydraulic-medium return pipe,

   d) at least one further hydraulic-medium return connector (120), produced preferably in one piece together with the tank lower part,

   e) at least one minimum marking and at least one maximum marking on an outer face of the wall (17) for identifying at least one intended minimum and at least one intended maximum fill level of the hydraulic medium in the hydraulic-medium receiving chamber, the markings being preferably produced in one piece together with the tank lower part (14),

   f) at least one holding structure, produced preferably in one piece together with the tank lower part, on an outer face of the wall for holding a hydraulic line or another component associated or to be associated spatially with the hydraulic tank.
8. Hydraulic tank according to any of claims 1 to 7, characterised in that at least the tank cover (32) and the tank lower part (14) of the hydraulic tank are produced from a thermoplastic plastics material, preferably a polyamide, most preferably a polyamide such as PA6 or PA12, and/or of a polypropylene (PP).
9. Industrial truck comprising a hydraulic tank (10) according to any of claims 1 to 8 which is associated with at least one hydraulic apparatus of the industrial truck and which is fixed to a frame of the industrial truck preferably by means of holding structures (42, 44, 70, 72) of the hydraulic tank.
10. Method for producing a hydraulic tank (10) which comprises:

    - a tank lower part (14) comprising a base (16) and a side wall (17),

    - a tank cover (32) which is connected to an upper edge of the side wall (17) and defines at least one hydraulic-medium receiving chamber together with the base (16) and the side wall (17),

    - at least one hydraulic-medium intake pipe (34) extending from a hydraulic-medium intake connector (36) of the tank cover (32), preferably into a lower region of the hydraulic-medium receiving chamber,

    - at least one hydraulic-medium return pipe (38) extending from a hydraulic-medium return connector (40) of the tank cover (32), preferably into a lower region of the hydraulic-medium receiving chamber,

    - at least one intermediate element (94a, 94b, 94c), which is preferably in the form of a partition which is open or comprises at least one hydraulic-medium passage, and which extends between and connects a front (18) and a rear (12) wall portion of the side wall (17), and

    - holding structures (78a, 78b; 80a, 80b; 82a, 82b), in the form of holding connecting pieces (78a, 78b; 80a, 80b; 82a, 82b) extending in the direction of a vertical axis of the hydraulic tank, on the wall inner face of the front (18) and the rear (12) wall portion, having in each case a holding aperture (96a, 96b) which extends in the direction of the vertical axis and, proceeding from a guide-through slot, widens in the transverse direction,

    wherein the method comprises the following production steps:

    A) production in one piece of the tank lower part (14), including the holding structures (78a, 78b; 80a, 80b; 82a, 82b) of the side wall (17), preferably by means of an injection-moulding process,

    B) production of at least one intermediate element (94a, 94b, 94c),

    C) insertion of the at least one intermediate element (94a, 94b, 94c) into the holding apertures (96a, 96b) of the two holding connecting pieces (78a, 78b; 80a, 80b; 82a, 82b) associated therewith in the direction of the vertical axis in order to form an interlocking engagement between the holding structures (78a, 78b; 80a, 80b; 82a, 82b) and the at least one intermediate element (94a, 94b, 94c),

    D) production of a tank upper part (30) which comprises the tank cover (32), the hydraulic-medium intake pipe (34) and the hydraulic-medium return pipe (38) and which can be assembled as a modular unit together with the tank lower part (14), by

    - producing, in one piece, the tank cover (32) or a one-piece modular unit comprising said tank cover and at least one (34) of the hydraulic-medium intake pipe (34) and the hydraulic-medium return pipe (38), preferably by means of an injection-moulding process, and

    - if not produced in one piece together with the tank cover (32):

    - - supplementing the tank cover or the modular unit with the hydraulic-medium intake pipe and/or the hydraulic-medium return pipe (38) to form a modular unit (30) which comprises the tank cover (32), the hydraulic-medium intake pipe (34) and the hydraulic-medium return pipe (38), and

    E) assembly of the tank upper part (30) and of the tank lower part (14) to form the hydraulic tank (10).
11. Method according to claim 10 for producing a hydraulic tank (10) according to any of claims 2 to 8.

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