EP0683864B1 - Hydraulic unit - Google Patents

Abstract

The invention pertains to a hydraulic unit with a concave oil tank (10) that has a holding capacity for oil between an external outer wall (13) and an internal outer wall (14) and with a pump unit (11) comprising an electric motor (21) and a pump (20) driven by the electric motor. Such a hydraulic unit is to be improved so as to have a low noise level while also ensuring sufficient cooling of the hydraulic medium and the electric motor (21). This problem is solved in that at least the pump (20), preferably the pump unit (11), is contained within a casing formed by the concave oil tank (10) and at least one sound absorbing element (60).

Description

The invention relates to a hydraulic unit, the essential components of which are an oil container and a pump unit according to the preamble of claim 1. The oil container is hollow and has a receiving volume for oil between an outer outer wall and an inner outer wall. The pump unit comprises an electric motor and a pump which can be driven by the electric motor.

Such a hydraulic unit, in which the electric motor is also air-cooled, is known from DE-GM 82 07 794. In this hydraulic unit, a hollow cylindrical oil tank and the pump unit are arranged upright. The oil tank is much shorter than the pump unit and is at a distance from the feet of a frame that supports the oil tank and the pump unit. Below the oil tank, a pipe, which is connected to the pressure connection of the pump, is wound into three radially superposed pipe spirals. The interior inside the inner outer wall of the oil tank and the pipe spirals is hermetically sealed near the floor, while it is covered at the top by a ventilation grille. A fan wheel is arranged on the side of the electric motor opposite the pump between the latter and the ventilation grille. In operation, it is supposed to push air out through the ventilation grille, which it has sucked in through the pipe spirals from the outside. It may be possible that the hydraulic oil flowing in the pipe spirals can be cooled in this way. However, it appears disadvantageous that the air warmed up when flowing through the tube spirals reaches the fan wheel along the electric motor. Sufficient cooling of the electric motor does not appear to be guaranteed by this. In addition to the problem of heat generation and the necessary cooling of the hydraulic oil and the electric motor belonging to the pump unit, hydraulic units have been using the humanization of workplaces for some time now Time increasingly brought the problem of noise generation and noise attenuation to the fore. This problem is not addressed in the publication mentioned.

The invention has for its object to develop a hydraulic unit with the features from the preamble of claim 1 so that the noise level is low. In addition, adequate cooling of the hydraulic oil and the pump unit, in particular the electric motor of the pump unit, is to be ensured by a further embodiment. It is also important to ensure that the hydraulic unit is easy to install.

The goal of low noise emissions is achieved for a hydraulic unit that has the features from the preamble of claim 1 by additionally having the features from the characterizing part of claim 1. The pump or the pump unit is encapsulated with the aid of the oil tank and one or more sound damping elements, so that the hydraulic unit has only a low noise level.

Advantageous embodiments of a hydraulic unit according to the invention can be found in the subclaims.

Mainly two principles are used to cool the hydraulic motor of a hydraulic unit that drives a hydraulic pump. One is the principle of air cooling. A fan wheel is assigned to the electric motor, which is usually driven by the electric motor itself and, with the aid of a guide plate, generates an air flow which sweeps over cooling fins on the outside of the motor housing. As a second principle, liquid cooling of the electric motor by means of the oil located in an oil reservoir of a hydraulic unit is known. For this type of cooling, the electric motor together with the pump is immersed in the oil in the oil container. The unit consisting of the electric motor and pump is then referred to as the sub-oil unit. Characterized in that the pump unit is immersed in the oil located in an oil container, is compared to a hydraulic unit in which the pump unit is outside the oil tank, the noise emissions are already reduced. A further reduction in noise is achieved if the oil container, which is referred to below as the second oil container, together with the lower oil unit, is accommodated in a capsule which is essentially formed by the hollow, first oil container and at least one sound-absorbing element, the outer wall of the second oil container and the inner outer wall of the first oil tank are spaced apart. The two oil tanks are connected to each other for oil exchange, so that heat transferred from the electric motor to the oil can be released to the outside via the first oil tank. Preferably, the pump will suck oil from the second oil container during operation, while a return line opens into the first oil container, so that a forced exchange of oil takes place between the two containers.

If the electric motor is air-cooled, a sound damping element is used according to claim 3 that is permeable to a flow of cooling air. The fan wheel sucks in cool air from the outside via a soundproofing element, blows it over the electric motor and pushes it out of the interior again through the same or a second soundproofing element. A soundproofing panel can consist of several spaced-apart foam panels with mutually offset openings. Since the sound can only propagate in a straight line, it is strongly dampened due to the offset openings. On the other hand, air can enter or leave the interior through the openings.

According to claim 4 it is provided that the hollow oil container is so large that the inner space delimited by the inner outer wall accommodates the entire pump unit or the entire second oil container, and that there is a soundproofing plate on an open side of the inner space. Due to the size of the hollow oil container, the outer outer wall now has a large area over which heat exchange between the oil in the oil container and a cooling medium surrounding the oil container, e.g. B. Air that can take place. This heat exchange is sufficient to keep the oil within the operating temperature range in many cases.

In the preferred embodiment according to claim 5, the hollow oil container is designed like a hollow cylinder with two open end faces, with a sound-absorbing element on each end face of the interior. It is not imperative that the hollow oil container have the same cross-section over its entire length. It is conceivable e.g. also that the hollow oil container is slightly frustoconical. However, it appears particularly favorable if the hollow oil container is a hollow cylinder which has the same cross section over its entire length. The sheets from which the outer walls of the hollow oil container are made can then be shaped particularly easily.

In a further preferred embodiment, which is specified in claim 6, the hollow oil container is trough-shaped with an open side, this open side being covered by a sound-absorbing element. The trough-like oil container can be arranged horizontally so that the interior is open in one direction against gravity upwards. There is then the advantage that a connection point between the two outer walls can easily be placed at a level above the maximum oil level, so that the risk of leakage from the oil container is very low. The trough-like oil container can then be open at the top and only covered. It is also possible to arrange the trough-like oil container upright so that the interior is open on the side, so that the bottoms of the two outer walls are more or less vertical. Depending on the spatial conditions at the location where the unit is used, the pump unit may then be more easily accessible than in any other arrangement. The pump unit is preferably arranged lying with its axis parallel to the bottom of the trough in the oil container, the oil container being preferably elongated in alignment with the shape of the pump unit. The horizontal arrangement of the pump unit enables it is a simple matter to provide a cooling air flow leading through the interior between two regions of the sound-absorbing element, through which the cooling air flow can pass. In addition, the stability is very high when the oil container is arranged horizontally.

According to claim 7, the outer outer wall of the trough-like hollow oil container is part of a machine stand, so in addition to the function as part of the oil container also has a supporting function for a machine. In particular, when the outer outer wall is part of a machine stand, it is provided with brackets to support the inner outer wall on the inside of its casing, from which the inner outer wall is supported. Another possibility of supporting the inner outer wall of a trough-like hollow oil container via the outer outer wall is to provide spacers between the bottoms of the two outer walls, on which the inner outer wall rests. According to claim 10, both outer walls of the hollow oil container are each guided to the outside on one open side, each with a flange-like section, and the two flange-like sections lie directly on one another or via a spacer element. If the hollow oil container is trough-like and arranged such that the trough is open at the top, the inner outer wall is supported in this way by the outer outer wall. The flange-like section can be used in the manufacture of the outer wall e.g. form in a deep-drawing process.

If there is oil in the oil container, a lifting force acts on the inner outer wall of the hollow oil container, against which the inner outer wall is to be held in position. This can be done, for example, by firmly connecting the two outer walls of the hollow oil container to one another, for example by means of screws or clips. Another possible solution is to hold the inner outer wall and, via this, the outer outer wall, firmly on a foundation. A particularly elegant solution according to claim 11 is that the weight of the pump unit or the second oil container, the inner outer wall against the buoyancy holds down. Of course, both the weight of the pump unit and the weight of the oil container can also be effective.

In a configuration according to claim 11, the pump unit and / or the second oil container are therefore carried by the hollow oil container. However, it also appears favorable if, according to claim 12, the hollow oil container and / or the pump unit and / or the second oil container are carried by a frame.

For the support of a trough-like oil container on a frame and for the seal between the two outer walls at the upper edge of the trough, it is advantageous if, according to claim 13, at least one outer wall of the oil container is guided to the outside with a flange-like section on an open side. The hollow oil container can be easily supported on the frame via the flange-like section of the outer wall. The flange-like section is advantageously encompassed with a clamp so that the hollow oil container cannot slip relative to the frame. Advantageously, as stated in claim 10, both outer walls are led outwards with a flange-like section and lie directly against one another or via a spacer, as a result of which they are positioned in relation to one another in terms of height. By using spacers of different thicknesses, as provided in claims 8, 9 and 10, the volume of the trough-like oil container can be varied without the need for other outer walls. A seal between the two outer walls of the hollow oil container takes place according to claim 14, preferably with the aid of an elastomer seal between the two outer walls, and with the aid of clamps which hold the two outer walls together with the elastomer seal being interposed.

Claim 15 specifies how, in an advantageous embodiment of a hydraulic unit according to the invention, which in particular has a trough-like hollow oil container, the pump unit can be adequately cooled.

By shielding the pump unit from the hollow oil container, as is provided according to claim 16, the noise emission of the unit is further reduced.

The sound reduction also contributes if, according to claim 17, a pulsation damper inserted into the pressure line of the pump is arranged within the interior space surrounded by the inner outer wall of the hollow oil container. The pulsation damper already brings with it a reduction in noise emissions. The hollow oil container is preferably essentially rectangular on the outside in cross section in order to utilize the available installation space as well as possible.

If a high cooling capacity is required for the hydraulic oil, the hydraulic unit is advantageously designed in such a way that a cooling liquid can flow around an outer wall of the hollow oil container. For this purpose, a third container wall can be provided at a distance from the outer wall of the hollow oil container.

A hollow oil container can be produced from plastic by blow molding in a particularly simple manner.

Several exemplary embodiments of a hydraulic unit according to the invention are shown in the drawings. The invention will now be explained in more detail with reference to these drawings.

Figur 1

bei aufgeschnittenem Ölbehälter eine Seitenansicht eines ersten Ausführungsbeispiels, das einen hohlzylindrischen Ölbehälter aufweist,

Figur 2

bei aufgeschnittenem Ölbehälter eine Draufsicht auf das erste Ausführungsbeispiel,

Figur 3

eine Ansicht in Richtung des Pfeiles A aus Figur 1, wobei jedoch die stirnseitige Schalldämpfungsplatte weggelassen ist,

Figur 4

einen Längsschnitt durch ein zweites Ausführungsbeispiel, das einen wannenartigen Ölbehälter aufweist, wobei die Pumpeneinheit nicht geschnitten ist,

Figur 5

einen Schnitt entlang der Linie V-V aus Figur 4, wobei nur eine Hälfte des Aggregats gezeigt ist,

Figur 6

einen Schnitt entlang der Linie VI-VI aus Figur 4,

Figur 7

ein drittes Ausführungsbeispiel, das einen wannenartigen hohlen Ölbehälter besitzt, dessen äußere Außenwand Teil eines Maschinengestells einer Kunststoffspritzgießmaschine ist,

Figur 8

einen Schnitt entlang der Linie VIII-VIII aus Figur 9 durch einen hohlzylindrischen Ölbehälter eines vierten Ausführungsbeispiels, der aus Kunststoff besteht und durch Blasformen hergestellt ist,

Figur 9

einen Schnitt entlang der Linie IX-IX aus Figur 8,

Figur 10

ein fünftes Ausführungsbeispiel, das einen wannenartigen hohlen Ölbehälter aufweist, der einen zweiten Ölbehälter mit einer Unteröleinheit im Abstand umgibt, und bei dem die beiden Ölbehälter nach Art von kommunizierenden Röhren miteinander verbunden sind,

Figur 11

einen Ausschnit aus einem sechsten Ausführungsbeispiel, das weitgehend mit demjenigen aus Figur 10 übereinstimmt, bei dem jedoch die beiden Ölbehälter über ein Steigrohr miteinander verbunden sind, und

Figur 12

ein siebtes Ausführungsbeispiel, bei dem nur die Pumpe gekapselt ist.

Show it

Figure 1

with the oil container cut open, a side view of a first exemplary embodiment which has a hollow cylindrical oil container,

Figure 2

with the oil container cut open, a top view of the first exemplary embodiment,

Figure 3

2 shows a view in the direction of arrow A from FIG. 1, but with the end-side sound-absorbing plate omitted,

Figure 4

2 shows a longitudinal section through a second exemplary embodiment which has a trough-like oil container, the pump unit not being cut,

Figure 5

3 shows a section along the line VV from FIG. 4, only one half of the unit being shown,

Figure 6

3 shows a section along the line VI-VI from FIG. 4,

Figure 7

a third exemplary embodiment which has a trough-like hollow oil container, the outer outer wall of which is part of a machine frame of a plastic injection molding machine,

Figure 8

9 shows a section along the line VIII-VIII from FIG. 9 through a hollow cylindrical oil container of a fourth exemplary embodiment, which consists of plastic and is produced by blow molding,

Figure 9

7 shows a section along the line IX-IX from FIG. 8,

Figure 10

5 shows a fifth exemplary embodiment which has a trough-like hollow oil container which surrounds a second oil container with a sub-oil unit at a distance, and in which the two oil containers are connected to one another in the manner of communicating tubes,

Figure 11

a section of a sixth embodiment, which largely corresponds to that of Figure 10, but in which the two oil tanks are connected to each other via a riser, and

Figure 12

a seventh embodiment in which only the pump is encapsulated.

The essential components of the hydraulic units shown are a hollow oil container 10 and a pump unit 11, which are carried by a separate frame 12 in the embodiments according to FIGS. 1 to 6 and 8 and 9.

The oil container 10 of the embodiment according to Figures 1 to 3 is hollow cylindrical, so has the same cross-section over its entire length, and has an outer outer wall 13 and an inner outer wall 14, between each of which an annular, the cross-section between the inner outer wall and the outer outer wall filling floor 15 is inserted. In the outer cross section, the container is essentially rectangular. At the top of the outer outer wall 13 is a nozzle 16 for filling oil and for ventilation of the container. In the two upper corners, the inner outer wall 14 has the same small radius as the outer outer wall at all four corners. The two lower corners of the inner outer wall 14 are less curved.

In the exemplary embodiments according to FIGS. 1 to 7, the pump unit 11 is of a commercially available type and is air-cooled. It includes a hydraulic pump 20, an electric motor 21, by which the hydraulic pump 20 is driven, and a fan wheel 22, which is fastened at one end of the electric motor 21 within a guide plate 23 on the shaft of the electric motor, that is to say is also driven by the electric motor. The fan wheel sucks air through the front slots of the guide plate 23 and presses it through a circumferential slot between the guide plate 23 and the housing of the electric motor, so that the air flows along the outside of the electric motor.

The frame 12 of the embodiment according to FIGS. 1 to 3 has two longitudinal beams 30 which are designed as angled profiles and which run through this interior space to approximately two thirds of the height of the interior space 31 surrounded by the inner outer wall 14 of the oil container. One leg 32 of a longitudinal beam 30 is lying parallel to the tops of the outer outer wall 13 or the inner outer wall 14 and the other leg 33 arranged perpendicular to the above-mentioned upper sides. So that the side members can run as close as possible to the pump unit, the respective upright leg is located at the outer longitudinal edge of the respective side leg 32, which is further away from a central plane 34 located between the two side members. The side members 30 protrude beyond the oil container 10 on its end faces and are rigidly connected to each other by a cross member 36 in front of each end. Each cross member 36 in turn projects beyond the side members 30 and rests there on a frame support 35. The frame supports 35 are thus largely outside the area inscribed by the inner outer wall 14 of the oil container 10, that is to say outside the cross-sectional area of the interior 31.

The pump unit 11 is suspended within the oil container 10 in the interior 31 on the side members 30 of the frame 12. For this purpose, four brackets 40 are attached to the electric motor 21. An elastic body 41 is inserted between two brackets located below a longitudinal beam 30 and the leg 32 of the relevant longitudinal beam, which extends along the longitudinal beam. It can be viewed as a damping bearing. Exactly above the elastic body 41, on the other side of the leg 32, there is a second damping bearing 42 which, in addition to an elastic body 41 which is supported directly on the leg 32, has a dimensionally stable plate 43 above the elastic body. A threaded bolt is inserted through each bracket 40, the damping bearing 41, the leg 32 of a longitudinal member and the damping bearing 42, onto which a screw nut is screwed below the bracket 40 and above the dimensionally stable plate 43. With the help of the clamping means 44 consisting of the threaded bolt and the two nuts, a bracket, the two damping bearings 41 and 42 and the longitudinal member are held together. The pump unit is thus suspended from the frame 12 in a sound-insulated manner. It is also ensured that the bracket 40 and the clamping means 44 do not touch the side members 30.

The hydraulic pump 20 is connected to the oil tank 10 via a suction line 45 and a further line 46. So that no structure-borne noise and no vibrations are transmitted to the oil container 10 via these lines, a piece of hose 47 is inserted into each of the two lines 45 and 46.

The noise reduction also contributes to the fact that a pulsation damper 49 is inserted into the pressure line 48 of the hydraulic pump 20 within the interior 31.

The oil container 10 lies freely on the longitudinal members 30 via two damping bearings 55. Each damping bearing 55 is located on an end face of the oil container and consists of a stable plate 56 extending across the two longitudinal beams 30 and an elastic body 57 which largely fills the cross section between the plate 56 and the inner outer wall 14 of the oil container 10 and on three sides of the inner outer wall 14 abuts. Thus, the oil tank cannot move in a direction perpendicular to its longitudinal direction relative to the damping bearing 55. The stable plate can be fixed e.g. be screwed to the side members 30 to prevent them from slipping on the side members. So there are two sound-absorbing transitions between the pump unit 11 and the oil tank, so that a very good vibration and structure-borne noise insulation is guaranteed.

The interior 31 is closed by the damping bearings 55 on the end faces of the oil container 10 in the area above the longitudinal beams 30. In addition, a soundproofing plate 60 is used to completely close one end face, which consists of a plurality of spaced apart foam layers with openings distributed over the entire surface of a layer. The breakthroughs of two adjacent layers of foam are offset from one another, so that on the one hand air can get into or out of the interior 31 and on the other hand noises generated by the pump unit can only reach the outside in a dampened manner since sound can only propagate in a straight line.

A so-called sound labyrinth is created through the various layers. In the area of the longitudinal beams 30, each soundproofing plate 60 is recessed in accordance with the contour of each longitudinal beam, so that the legs 32 and 33 of a longitudinal beam can pass through them. Outside the longitudinal beams 30, each soundproofing plate 60 extends to the stable plate 56 of the damping bearing 55 assigned to the respective end face. Thus, the pump unit 11 and the pulsation damper 49 are located within the encapsulated interior 31. A high level of noise damping is thus ensured. Of course, for another line connected to the pulsation damper 49, but not shown in detail, there is still an opening in one of the damping bearings 55 or one of the sound damping plates 60. It has been shown that simply inserting a pulsation damper into the pressure line directly at the pressure outlet of the pump, in addition to damping the pressure pulsations in the hydraulic medium, also brings about a substantial reduction in noise. The additional arrangement of the pulsation damper in an encapsulated cavity further reduces the perceptible noise level. The unit can also be arranged upright.

The hydraulic unit according to FIGS. 4 to 6 has a trough-like oil container 10, the two outer walls 13 and 14 of which are deep-drawn and each have a bottom 65, four side parts 66 and a flange 67 guided outwards at the upper edge. Between the outer walls 13 and 14 there is the same distance everywhere in the area of the floors and the side parts. However, the distances, in particular between the bottoms 65 on the one hand and the side parts 66 on the other hand, can also be different. Two opposite side parts of each outer wall are longer than the other two side parts, so that the oil container 10 has an elongated shape overall. The flange 67 of the inner outer wall 14 is wider than the flange 67 of the outer outer wall 13. Both flanges 67 end exactly one above the other on the outside. An elastomer seal 68 is inserted between the flanges 67, which is similar to the bottoms 15 of the embodiment according to FIGS Figures 1 to 3 closes off the space between the two outer walls 13 and 14 which holds the hydraulic oil, but which is above the maximum oil level indicated by arrows in Figures 4 and 6, so that in the oil tank of the unit according to Figures 4 until 6 the risk of leakage is very low. From the figures it can be seen that the bottoms 65 of the two outer walls 13 and 14 are of different sizes. The same applies to the side parts 66 and the flanges 67. It is conceivable to shape the outer walls in the manner of truncated pyramids, so that a space for receiving oil can be obtained even with completely identical outer walls. By varying the heights of the elastomer seal 68, which also acts as a spacer, the volume of the intermediate space can be made different in size. The elastomer seal also serves to isolate structure-borne noise between the inner and outer outer wall of the oil tank.

The outer wall 13 is surrounded at a short distance by a further container wall 69, the upper edge of which is also guided outwards as a flange-like section 67. Water can flow between the outer wall 13 and the container wall 69, through which the hydraulic oil located between the two outer walls 13 and 14 can be cooled. Appropriate barriers between the two walls 13 and 69 can ensure that the water flows in the manner of a cooling coil from an entrance to an exit. An elastomer seal 70 is located between the flanges 67 of the outer wall 13 and the container wall 69.

The pump unit 11 of the embodiment according to FIGS. 4 to 6 is also located entirely in the inner space 31 delimited by the inner outer wall 14 and in turn has an electric motor 21, by which a hydraulic pump 20 and a fan wheel located inside a guide plate 23 can be driven. The pump unit 11 is arranged with its axis in the longitudinal direction of the oil container 10 in its interior 31 and suspended from a frame 12. Similar to the embodiment according to FIGS. 1 to 3, this frame includes four frame supports 35, which are two each on a long side of the oil tank 10 outside of this. The oil container 10 lies with its flanges 67 on damping bearings 71 on the frame supports 35. A damping bearing 71 is also inserted between a foundation and each frame support 35. On each frame support 35, the three flanges 67 with the elastomer seals 68 and 70 located between them and with the damping bearing 71 located below the flange 67 of the container wall 69 and with another damping bearing 71 placed on the flange 67 of the inner outer wall 14 are held together with a clamp 72 . Two supports 30 extend above the oil container 10 across the interior 31 and are each fastened to two mutually opposite frame supports 35. Within the interior 31, the two carriers 30 are connected to one another via two further carriers 73 which run in the longitudinal direction of the container 10 and which are suspended from the carriers 30 via damping bearings 71. The carriers 73 are located close to the inner outer wall 14 of the oil container 10, so that they do not unnecessarily complicate access to the hydraulic pump 20, over which the one carrier 30 passes. Finally, two further supports 74, which run parallel to the supports 30 but have a smaller spacing from one another than the supports 30, are fastened directly to the supports 73, on which the pump unit 11 is provided with fastening eyes 75, which are formed integrally with the housing of the electric motor 21 is hung. It is also conceivable to reduce the distance between the carriers 73 or to let the fastening eyes 75 run obliquely outwards, so that the pump unit 11 is directly attached to the carriers 73 and the carriers 74 can be dispensed with.

On the flange 67 of the inner outer wall 14 of the oil container 10, a two-part soundproofing plate 80 is placed, which is separated in the area of the interface between the electric motor 21 and hydraulic pump 20, so that only one part of the soundproofing plate 80 has to be lifted off to access the hydraulic pump 20 . The soundproofing plate has corresponding recesses for the beams 30, the damping bearings 71 between the beams 30 and the supports 73 and for the brackets 72. In the region of each narrow side part of the oil container 10, the soundproofing plate 80 is provided with an opening 81 or 82 which opens directly into the interior 31 inside the side parts 66 of the inner outer wall 14. The openings 81 and 82 to the pump unit 11 are each shielded by a sound damping plate 83, which is arranged perpendicular to the longitudinal axis of the pump unit 11 and projects from the sound damping plate 80 into the interior 31, but at a distance from the bottom 65 of the inner outer wall 14 of the container 10 Has. The sound damping plates 83 can be permeable to air over their entire extent. On the other hand, a partition 84, which is arranged transversely to the axis of the pump unit 11 and extends between the guide plate 23 on the one hand and the inner outer wall 14 of the oil container 10 and the soundproofing plate 80 on the other hand, is not air-permeable. The partition 84 ensures that the fan wheel only sucks air from the passage 81 and does not create a closed air flow leading through the fan wheel within the interior 31.

In operation, air flows through the passage 81 of the sound-absorbing plate 80 into the interior 31 and reaches the fan wheel between the sound-absorbing plate 83 associated with the passage 81 and the bottom 65 of the inner outer wall 14, is pressed by it along the pump unit 11 and flows around the other Soundproofing plate 83 around passage 82, through which it is released again. As can be seen, the two openings of the passage 82 are offset from one another by the width of this passage into the interior 31 and into the open. Of course, the passage 81 can also be designed in this way. This further reduces the noise emission of the hydraulic unit.

While the permeability for a cooling air flow in the sound absorbing plate 80 is primarily created by the passages 81 and 82, the sound absorbing plates 60 of the embodiment according to FIGS. 1 to 3 are permeable to air.

The pump unit 11 is shielded from the oil tank 10 by sound-absorbing plates 90, which are arranged between the pump unit and the long side parts of the inner outer wall 14 and extend between the wall 84 and the one wall 83. For example, plates that are commercially available under the name "compact absorber" can be used for this.

The hydraulic unit for the plastic injection molding machine partially shown in FIG. 7 has in principle the same structure as the hydraulic unit from FIGS. 4 to 6. A trough-like, hollow oil container 10 has a trough-like outer wall 13 and a trough-like inner wall 14, which includes an interior space 31 , in which the pump unit 11 is completely accommodated. This consists of an air-cooled electric motor 21 with a fan wheel located inside a guide plate 23 and a hydraulic pump 22 which can be driven by the electric motor.

An essential difference between the embodiment according to FIG. 7 and the embodiment according to FIGS. 4 to 6 is that the outer outer wall 13 of the embodiment according to FIG. 7 is now part of the machine frame of the plastic injection molding machine. In particular, the side parts 66 of the outer outer wall 13 thus have a supporting function for the machine. At a distance from the floor 65, brackets 85 are fastened to the inside of the side parts 66, on which the inner outer wall 14 of the oil container 10 rests with a flange 67 via a spacer 68, which can also act as a seal.

The pump unit 11 is fastened to two supports 73 via fastening eyes 75, which are suspended from two longitudinal supports 30 via damping elements 71. These rest on the flange 67 of the inner outer wall 14 via damping bearings 86. The weight of the pump unit 11 thus rests on the inner outer wall 14 of the oil container 10 and holds it down on the brackets 85 against the buoyancy of the oil in the container 10. There are no special connecting elements, e.g. screws, between the flange 67 and the brackets 85 necessary. The elastomer seal 68 and the damping bearing 86 can easily be designed so that the inner outer wall 14 and the pump unit 11 cannot slip relative to one another and to the outer outer wall 13. As in the embodiment according to FIGS. 4 to 6, a sound absorbing plate 80 covers the interior 31. This has the passages 81 which lie in the air flow cooling the electric motor. The passages 81 to the pump unit 11 are covered by sound damping plates 83 arranged perpendicular to the sound damping plate 30. As can be seen from FIG. 7 and the above description, the pump unit 11 is carried by the inner outer wall 13 of the oil container 10, that is to say by the oil container 10. There is no additional frame in this version.

The hollow cylindrical oil container 10 according to FIGS. 8 and 9 is made in one piece from a plastic by blow molding, a maintenance opening 87 is provided on it, which leads from the outside through the outer walls 13 and 14 into the interior 31 and is located at such a point, that you can easily get through it to a pump located in the interior 31. The maintenance opening is normally closed by a sound absorbing insert and is only opened for maintenance. On the oil container 10 are a piece 16, which is used for filling oil and a piece 88 is formed, which surrounds a cleaning opening and which, viewed in the longitudinal direction of the oil container 10, is located in the center of the oil container.

The two hydraulic units according to FIGS. 10 and 11 in turn, like the embodiments according to FIGS. 4 to 6 and according to FIG. 7, have a trough-like hollow oil container 10 with an outer trough-like outer wall 13 and an inner trough-like outer wall 14. The bottom 65 of the outer wall 13 stands via block-like elastic bearings 89 on a foundation 90. The floor 65 becomes by further elastic bearings 89, which are located exactly above the bearings between the outer wall 13 and the foundation 90 the outer wall 14 is held at a distance from the bottom 65 of the outer wall 13 and the outer wall 14 is supported on the outer wall 13.

The pump unit 11 of the two versions according to FIGS. 10 and 11 is a so-called sub-oil unit which has no fan wheel and which is immersed in oil within a second oil container 91. The pump unit 11 is suspended obliquely on two supports 73 via elastic bearings 71 in such a way that the electric motor 21 is practically completely under oil, but the pump 20 looks out of the oil in some areas. In this area of the pump, e.g. electronic components are located, which advantageously remain free of oil.

The second oil tank 91 is located within the inner space 31 delimited by the inner outer wall 14 of the first oil tank, is of a conventional design and has a single trough-like outer wall 92, the bottom 65 of which, via elastic bearings 89, is spaced apart from the bottom 65 of the inner outer wall 14 of the first Oil container 10 is held. There is also a distance between the side parts of the outer walls 14 and 92. The carriers 73 rest on the outer wall 92 of the second oil container, so that in addition to the weight of the oil container 91 and the weight of the pump unit 11, the inner outer wall 14 of the oil container 10 holds down over the uppermost blocks. A firm connection between the two outer walls 13 and 14 of the oil container 10 or a direct connection of the inner outer wall 14 to the foundation 90 is not necessary.

The two oil reservoirs 10 and 91 communicate with one another via a tube 93, which leads through the intermediate space 94 between the outer walls 14 and 92 and starts from an opening in the bottom 65 of these two outer walls. Instead of a tube, an elastic hose can also be used. Advantageously, the pump 20 sucks in oil, which is located in the second oil tank 91, while the return line opens into the first oil tank 10, so that an oil exchange between the oil tanks takes place. The warm one coming out of the return line Oil emits its heat primarily via the outer outer wall 13 of the oil container 10, but also via the inner outer wall 14 of this oil container. The outer wall 92 of the second oil container also contributes to the heat emission.

Both oil containers 10 and 91 are covered by a sound absorbing plate 80. This has in the area of the space 94 air slots 95, so that the air located in the space 94 can be exchanged and heat can be transported to the outside. Depending on the cooling required, a cooling air flow or a cooling water flow can also be forcibly generated through the intermediate space 94. Instead of the more or less cuboid bearings 89, bearings can also be used which have an angular recess in which the trough-like outer walls 13, 14 and 92 sit with a corner. At the same time, the bearings 89, which are located between the outer walls, can extend into the inner corners of the outer walls 13 and 14. In this way, they position the outer walls to each other. The space 94 can be filled with sand for higher noise insulation.

In the embodiment according to FIG. 10, there is a direct connection between the inner outer wall 14 of the oil container 10 and the outer wall 92 of the oil container 91 via the tube 93, even if it is designed as an elastic hose. This is avoided in the embodiment according to FIG. 11, in which the two oil volumes in the oil tanks 10 and 91 are in exchange with one another via a U-shaped riser pipe 96, which extends over the outer wall 92 of the oil tank 91 and over the inner outer wall 14 of the oil tank 10 and with one end into which the Oil tank 91 and with its other end immersed in the oil in the oil tank 10. With such a construction there is no danger that the connection point between the two oil containers will leak and oil will get into the intermediate space 94. The riser pipe can be held on the sound absorbing plate 80, for example.

In contrast to all of the previously described exemplary embodiments, in the case of the one according to FIG. 12, only the pump 20 of the pump unit 11 is encapsulated by the hollow oil container 10 and by a sound-absorbing plate 80. The hollow oil container 10 is in turn trough-shaped with an inner outer wall 13 and an outer outer wall 14. Both outer walls are drawn outwards in flanges 67 at the upper edge of the oil container 10 and lie there on one another via an elastomer seal 68. To pass the pump unit 11 from the outside into the interior 31, the soundproofing plate 80 has an opening 97. The weight of the pump unit rests on one or more supports 30 and on damping bearings 86 on the flange 67 of the inner outer wall 14 and thus when there is oil in the oil container 10 is located on the flange 67 of the outer outer wall 13 in order to reduce the buoyancy on the inner outer wall 14. The carriers 30 are located in recesses on the inner side of the soundproofing plate 80.

In the hydraulic unit according to FIG. 12, the pump unit 11 can be supported on the oil container 10 in a particularly simple manner by means of supports 30. The fact that the interface between the pump 20 and the electric motor 21 is just at the level of the upper edge of the oil container 10 enables support with a straight support 30. With the pump, which is cooled by the hydraulic oil, an essential noise source of the hydraulic unit is encapsulated . The electric motor is located outside the capsule, so that no further measures have to be taken beyond the usual measures for cooling the electric motor. Due to the vertical arrangement of the pump unit, a hydraulic unit can be realized that takes up only a small footprint.

Pump 20 and electric motor 21 are connected to one another in the usual way by means of an elastic pump support, whereby the transmission of structure-borne noise and vibrations is largely avoided. The pump vibrations are isolated and dampened by a temperature and liquid-resistant rubber ring that transmits all forces in a positive manner. One uses a torsionally flexible coupling between the motor shaft and the pump shaft, there is no longer a metallic connection between the pump and motor. An elastic bellhousing of conventional design is described, for example, in the book "Fundamentals and Components of Fluid Technology Hydraulics Volume I", 1991, published by the applicant, page 295 ff.

In a hydraulic unit according to the invention, a pulsation damper known per se, or an intermediate tank acting as a volume resonator, is inserted with particular advantage into the suction line of the pump and into the interior of the capsule or into the oil-absorbing volume. Because the airborne sound radiation from the pump is greatly reduced in an assembly according to the invention, the sound radiation through the oil tank is of greater importance. This sound radiation is reduced by the pulsation damper or intermediate tank.

Claims (21)

1. A hydraulic unit having a hollow oil container (10) which has a receiving space for oil between an external outer wall (13) and an internal outer wall (14), and having a pump unit (11) which comprises an electric motor (21) and a pump (20) which can be driven by said motor, characterized in that at least the pump (20) and preferably the pump unit (11) is contained in an enclosure formed essentially by the hollow oil container (10) and at least one sound-damping element (60, 80).
2. A hydraulic unit according to Claim 1, characterized in that a second oil container (91) is present, that the pump unit (11) is arranged as sub-oil unit within the oil receiving space of the second oil container (91), that the second oil container (91), together with the pump unit (11), is contained in an enclosure formed essentially by the hollow first oil container (10) and at least one sound-damping element (80), the outer wall (92) of the second oil container (91) and the internal outer wall (14) of the first oil container (10) being spaced from each other, and that the two oil containers (10, 91) are connected with each other for the exchange of oil.
3. A hydraulic unit according to Claim 1, characterized in that the electric motor (21) is air-cooled and a fan wheel (22) can be driven by it, and that the sound-damping element (60, 80) is pervious to a stream of cooling air.
4. A hydraulic unit according to any of the preceding claims, characterized in that the hollow oil container (10) is so large that the inner space (31) defined by its internal outer wall (14) receives the entire pump unit (11) or the entire second oil container (91); and that a sound-damping plate (60, 80) is present on one open side of the inner space (31).
5. A hydraulic unit according to any of the preceding claims, characterized in that the hollow oil container (10) is shaped as a hollow cylinder with two open ends, and that a sound-damping element (60) is present on each end of the inner space (31).
6. A hydraulic unit according to any of Claims 1 to 5, characterized in that the hollow oil container (10) is shaped as a trough with an open side, and that the open side is covered by a sound-damping element (80).
7. A hydraulic unit according to Claim 6, characterized in that the external outer wall (13) of the trough-shaped hollow oil container (10) forms part of a machine stand and, in particular, part of the stand of a plastic injection moulding machine.
8. A hydraulic unit according to Claim 6 or 7, characterized in that the external outer wall of the trough-shaped hollow oil container (10) is provided on the inner side of its side parts (66) with brackets (85) by which the internal outer wall (14) is supported directly or via spacers (68).
9. A hydraulic unit according to Claim 6 or 7, characterized in that the internal outer wall (14) of the trough-shaped hollow oil container (10) is supported on the external outer wall (13) via spacers (89) which are present between the bottoms (65) of the two outer walls (13, 14).
10. A hydraulic unit according to any of the preceding claims, characterized in that, on an open side, the two outer walls (13, 14) of the hollow oil container (10) are each extended outwards by a flange-shaped section (67), and that the two flange-shaped sections (67) rest on each other directly or via a spacer (68).
11. A hydraulic unit according to any of Claims 6 to 10, characterized in that the internal outer wall (14) of the hollow oil container (10) is held down against a buoyancy force acting on it by the pump unit (11) or the second oil container (91), the pump unit (11) and/or the second oil container (91) being supported by the hollow oil container (10).
12. A hydraulic unit according to any of the preceding claims, characterized in that the hollow oil container (10) and/or the pump unit (11) and/or the second oil container are supported by a frame (12).
13. A hydraulic unit according to claim 12, characterized in that, on an open side, at least one outer wall (13, 14) of the hollow oil container (10) is extended outward by a flange-like section (67), and that the hollow oil container (10) is supported on the frame (12) via the flange-like section (67) of the outer wall (13, 14), and that the frame (12) grips the flange-like section (67) by means of a clamp (72).
14. A hydraulic unit according to any of the preceding claims, characterized in that the two outer walls (13, 14) of the hollow oil container (10) are held together by clamps with the interposition (68) of an elastomeric packing (68) running circumferentially above the maximum oil level preferably between a section (67) of the external outer wall (13) extending outward in flange-like manner and a section (67) of the internal outer wall (14) extending outward in flange-like manner.
15. A hydraulic unit according to any of the preceding claims, characterized in that an air-impervious wall (84) is arranged in the plane of the fan wheel (22) between the latter and the internal outer wall (14) of the hollow oil container (10) or a sound-damping element (80) closing off an open side of the inner space (31).
16. A hydraulic unit according to any of the preceding claims, characterized in that a sound-damping element (90) is arranged between the pump unit (11) and the internal outer wall (14) of the hollow oil container (10).
17. A hydraulic unit according to any of the preceding claims, characterized in that a pulsation damper (49) inserted in the pressure line (48) of the pump (20) is arranged within the inner space (31) bounded by the internal outer wall (14) of the hollow oil container (10).
18. A hydraulic unit according to any of the preceding claims, characterized in that at a distance from the outer wall (13) of the hollow oil container (10) there is a third container wall (69), and that the hollow space between the two walls (13, 39) permits passage of the cooling liquid.
19. A hydraulic unit according to any of the preceding claims, characterized in that the hollow oil container (10) is made of plastic by blow moulding.
20. A hydraulic unit according to any of the preceding claims, characterized in that the hollow cylindrical oil container (10) has a maintenance opening (87) which passes through its two outer walls (13, 14) and leads into the inner space (31).
21. A hydraulic unit according to any of the preceding claims, characterized in that a pulsation damper or intermediate tank is inserted in the suction line of the pump.

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