Pump unit for a hydraulic system and channel element for a pump unit

Abstract

Pump unit (1, 110) for a hydraulic system comprising a housing (2) and a connection area (3), wherein the housing (2) defines an interior space (4), the interior space (4) being substantially cylindrical and forming at least a portion of an oil reservoir (T) that can be filled with hydraulic oil; and at least one pump element and at least one submersible electric motor (5) driving the pump element are arranged in the interior (4); wherein the connection area (3) has a pressure channel (6) with a pressure channel opening (7) and a return channel (8), wherein the pressure channel opening (7) is connected to the pump element and the return channel (8) opens into the interior (4) via a return opening (9), wherein the pump unit (1) has a channel element (100, 111) arranged in the interior (4) with a channel element inlet (101) and a channel element outlet (102), wherein the channel element (100) is formed separately from the housing (2), wherein the channel element inlet (101) is connected to the return opening (9), and the channel element outlet (102) is spaced from the connection area (3) such that the channel element outlet (102) projects into the interior (4) below an oil level (S) in the oil reservoir (T) which is established during operation of the pump unit (1), wherein the channel element outlet (102) is offset by at least 45° to 120° relative to the return opening (9) in the circumferential direction of the interior space (4), and the central axis (MA) of the channel element outlet (102) is not parallel to the central axis (MR) of the return opening (9), and wherein the housing (2) has at least one fastening element (11) and wherein the channel element (100) has at least one fastening means (105) fixed to the fastening element (11).

Description

[0001] The present invention relates to a pump unit for a hydraulic system with a housing and a connection area.

[0002] In such pump units, the housing defines an interior space that at least partially forms an oil reservoir that can be filled with hydraulic oil. Furthermore, at least one pump element and at least one submerged-oil electric motor driving the pump element are arranged in the interior space. The connection area has a pressure channel with a pressure channel opening and a return channel, wherein the pressure channel opening is connected to the pump element and the return channel opens into the interior space of the housing via a return opening. A return opening within the meaning of the invention is understood to be the opening through which returning hydraulic oil can escape into the interior space largely unhindered.

[0003] Gear pump elements, radial piston pump elements, or combinations of these two pump elements can be used as pump elements. Such a pump unit is known, for example, from EP 1 731 762 A1. Other pump units are known from DE 200 07 554 U1, DE 10 2016 225 923 A1, and DE 198 59 340 C2.

[0004] Such pump units are used to supply hydraulic systems with pressurized hydraulic oil. The pump element is rotationally driven by the submerged oil electric motor and generates a nearly continuous volume flow of hydraulic oil through the pressure channel opening into the pressure channel. The hydraulic components, such as a spool valve assembly and corresponding hydraulic consumers, are connected to the pressure channel. Therefore, the housing-side outlet of the pressure channel in the connection area usually represents the P-connection of the hydraulic system. The hydraulic oil returning from the hydraulic system is in turn fed back into the oil reservoir via the return channel by exiting through the return opening into the interior. Therefore, the housing-side inlet of the return channel in the connection area usually represents the T-connection of the hydraulic system.

[0005] In the pump unit known from EP 1 731 762 A1, the return opening is arranged such that, when the pump unit is in a horizontal operating position, it is above the oil level in the oil reservoir. In the following, a horizontal operating position is understood to mean an operating position of the pump unit in which the longitudinal axis of the housing or the pump unit is approximately horizontal. Particularly in this horizontal operating position of the pump unit, problems can arise during operation of the pump unit.

[0006] The returning hydraulic oil exits the return port above the oil level below atmospheric pressure at a pressure above atmospheric pressure and splashes against the opposite inner wall of the housing. This can cause the hydraulic oil to foam, causing foamed hydraulic oil to leak from the pump unit. Furthermore, the foamed hydraulic oil has a detrimental effect on the entire hydraulic system, for example, by introducing air into the hydraulic system, which can damage the hydraulic system components.

[0007] Since an air filter is preferably provided in the area of ​​the housing opposite the return opening, it must be protected from the injecting hydraulic oil by appropriate means, for example, by using a baffle plate or the like. Although this effectively prevents the air filter from becoming clogged with hydraulic oil, it does not prevent the hydraulic oil from foaming due to the continued mechanical stress on the returning hydraulic oil.

[0008] Furthermore, operating the pump unit in an upright position has the disadvantage that the injecting hydraulic oil can clog the air filter, and a baffle plate during upright operation actually increases the foaming of the hydraulic oil. This is particularly problematic when the returning hydraulic oil is released into the interior in a surge. An upright operating position is defined as an operating position of the pump unit in which the longitudinal axis of the housing or pump unit is approximately vertical.

[0009] It is therefore an object of the present invention to provide a pump unit for hydraulic systems with which foaming of the returning hydraulic oil can be effectively prevented and a good mixing of the returning hydraulic oil with the hydraulic oil present in the oil reservoir can be achieved.

[0010] This object is achieved with the pump unit according to claim 1. Advantageous further developments are described in the dependent claims.

[0011] The pump unit according to the invention is distinguished from the pump units of the prior art in that the pump unit has a channel element arranged in the interior with a channel element inlet and a channel element outlet, wherein the channel element inlet is connected to the return opening, and the channel element outlet is spaced apart from the connection area. This makes it possible to specifically redirect the returning hydraulic oil via the channel element before it escapes. In particular, the channel element outlet is spaced apart from the connection area such that the channel element outlet opens into the interior of the housing below an oil level that arises in the oil reservoir during operation of the pump unit. Consequently, the returning hydraulic oil is introduced into the oil reservoir below the oil level that arises during operation.The channel element outlet is therefore expediently arranged radially inward of the return opening relative to a horizontal longitudinal axis of the pump unit when in a horizontal operating position, viewed from the side.

[0012] This prevents the returning hydraulic oil from escaping into the atmosphere, thus preventing excessive mechanical stress on the returning hydraulic oil. Instead, the returning hydraulic oil is fed directly into the hydraulic oil in the reservoir, which dampens the flow of the returning hydraulic oil accordingly. This effectively prevents foaming of the returning hydraulic oil.

[0013] According to the invention, the interior is essentially cylindrical, with the channel element outlet offset by at least 45° to 120° relative to the return opening in the circumferential direction of the interior. This allows for particularly good mixing of the returning hydraulic oil with the hydraulic oil present in the oil reservoir. This prevents the returning and already heated hydraulic oil from being directly sucked back into the pump element. This has the disadvantage of reducing the hydraulic performance and the continuous operating time of the pump unit. Furthermore, excessive heating of the hydraulic oil can also lead to damage to the pump element.

[0014] According to the invention, the central axis of the channel element outlet is not parallel to the central axis of the return opening or the channel element inlet. In particular, it is expedient if the central axis of the channel element outlet runs essentially perpendicular to the central axis of the return opening or the channel element inlet. This allows the returning hydraulic oil to be introduced into the hydraulic oil in the oil reservoir with a directed movement component. Thus, the returning hydraulic oil mixes well with the hydraulic oil in the oil reservoir.

[0015] It is advantageous if the channel element has a deflection section connecting the channel element inlet and the channel element outlet, wherein the deflection section has an at least partially open side. If the channel element is not completely closed and is tubular, this simplifies the production of the channel element. Furthermore, the channel element can be manufactured more cost-effectively due to the lower material requirements.

[0016] In this context, it is advantageous if the open side of the deflection section rests against an inner wall of the housing. By closing the open side, the inner wall of the housing can prevent the returning hydraulic oil from escaping through the open side of the deflection section. Furthermore, this also allows for better cooling of the heated and returning hydraulic oil, as it is guided along the inner wall of the housing. In this context, it is also advantageous if the returning hydraulic oil exits the channel element outlet in such a way that it flows along the inner wall of the housing, thus achieving improved cooling overall.

[0017] According to the invention, the channel element is formed separately from the housing, with the housing having at least one fastening element and the channel element having at least one fastening means attached to the fastening element. This facilitates the manufacture of the channel element. Furthermore, the assembly of the channel element and the overall assembly of the pump unit is simplified.

[0018] It is advantageous if the fastening element is a bore with an anchoring structure, and the fastening means is a stud with locking elements, wherein the anchoring structure is, in particular, an internal thread. A bore with an internal thread serving as an anchoring structure can be easily produced during the manufacture of the housing. Furthermore, the channel element can be quickly and easily secured to the housing by inserting the stud into the bore, since the locking elements on the stud engage with the threads of the internal thread.

[0019] In a further development, the channel element has at least one disassembly means, wherein the disassembly means is in particular a projection with preferably an opening. To disassemble the channel element, for example, a hook can be inserted into the opening of the projection, so that the channel element can be removed from the interior of the housing by applying force to the hook.

[0020] The channel element is advantageously made of a plastic, particularly a glass-fiber-reinforced polyamide. Consequently, the channel element can be manufactured cost-effectively as an injection-molded part. Furthermore, polyamide has good chemical resistance. The glass-fiber reinforcement ensures good mechanical properties in terms of the strength and durability of the channel element.

[0021] It is advantageous if the housing is a cast part, particularly an aluminum die-cast part or an aluminum gravity die-cast part. It is also conceivable for the housing to be made of aluminum gravity die-casting and subsequently machined. This allows the compressive strength required for the operation of the pump unit to be achieved while simultaneously keeping manufacturing costs low.

[0022] The invention further relates to a channel element for use with a pump unit for a hydraulic system. The pump unit has a housing defining an interior space and a connection area. The interior space is substantially cylindrical and at least partially forms an oil reservoir fillable with hydraulic oil. At least one pump element and at least one submerged oil electric motor driving the pump element are arranged in the interior space. The connection area has a pressure channel with a pressure channel opening and a return channel, wherein the pressure channel opening is connected to the pump element and the return channel opens into the interior space via a return opening. According to the invention, the channel element inlet is connected to the return opening, and the channel element outlet is spaced from the connection area such that the channel element outlet opens into the interior space below an oil level that arises in the oil reservoir during operation of the pump unit.Furthermore, the channel element has a channel element inlet, a channel element outlet offset by at least 45° to 120° relative to the return opening in the circumferential direction of the interior space, and a deflection section connecting the channel element inlet and the channel element outlet, wherein the center axis of the channel element outlet is not parallel to the center axis of the channel element inlet. According to the invention, the channel element has at least one fastening means for fastening the channel element to a housing of the pump unit.

[0023] When using such a channel element with a pump unit, as known, for example, from EP 1 731 762 A1, the advantages described above with regard to the pump unit according to the invention are achieved. In particular, a channel element according to the invention can effectively prevent foaming of the returning hydraulic oil and achieve good mixing of the returning hydraulic oil with the hydraulic oil present in the oil reservoir.

[0024] The invention is explained in more detail below using an exemplary embodiment. The following schematically show: Fig. 1 a side view of a pump unit according to the invention according to a first embodiment; Fig. 2 a perspective view of a housing base body of the Fig. 1 pump unit shown; Fig. 3 a plan view of the Fig. 2 shown housing base body; Fig. 4 a sectional view along the Fig. 2 shown line A - A; Fig. 5 a sectional view along the Fig. 2 shown line B - B; Fig. 6 a side view of the Fig. 2 shown housing base body; Fig. 7 a sectional view along the Fig. 6 shown line C - C; Fig. 8 a sectional view along the Fig. 6 shown line D - D; Fig. 9 - 14 different views of a channel element according to the invention according to the first embodiment; Fig. 15 is a plan view of a housing base body of a pump unit according to a second embodiment which is not part of the invention; Fig. 16 a side view of the Fig. 15 shown housing base body; Fig. 17 a section along the Fig. 15 shown line E - E; Fig. 18 a section along the Fig. Line F - F shown in 16.

[0025] In Fig. 1 shows a pump unit 1 according to the invention in a first embodiment. The pump unit 1 is a motor-pump unit which provides a required hydraulic output in continuous or intermittent operation. As shown, the pump unit 1 has a housing 2, which consists of a largely cylindrical housing base body 2a and two housing covers 2b, 2c tightly attached thereto. The housing covers 2a, 2b are fastened to the housing base body 2 with, for example, four screws each. Longitudinal ribs for cooling are provided on the outer circumferential surface of the housing base body 2a. The housing base body 2a is expediently an aluminum die-cast part or an aluminum permanent mold casting. The housing covers 2b, 2c are aluminum die-cast parts in this embodiment.

[0026] The housing 2 further comprises a connection area 3, via which the pump unit 1 is connected to a hydraulic system (not shown). The housing 2 defines an interior space 4, wherein the interior space 4 at least partially forms an oil reservoir T that can be filled with hydraulic oil.

[0027] As in the Fig. 2, Fig. 3, Fig. 7 and Fig. As shown in Figure 8, the connection area 3 has a pressure channel 6 with a pressure channel opening 7. The pressure channel opening 7 is connected to a pump element (not shown) arranged in the interior space 4. Furthermore, the connection area 3 has a return channel 8 with a return opening 9. The return opening 9 opens into the interior space 4 of the housing 2, specifically with respect to a central axis MP (cf. Fig. 7) of the pump unit 1 above the pressure channel opening 7. The latter is well integrated into the Fig. 7 and Fig. 8. Furthermore, in Fig. 8 that the central axis MR of the return opening 9 runs essentially parallel to the central axis MP of the pump unit 1.

[0028] The housing base body 2a has an inner wall 10 and a transverse wall 13 with a central passage 14 and a stator retaining collar 15. The inner wall 10 defines the approximately cylindrical interior 4 of the housing 2, which is divided by the transverse wall 13. A submerged oil electric motor 5 is attached to the transverse wall 13 via a stator 17. For this purpose, the stator 17 is fixed to the stator retaining collar 15 via a bearing plate 19 screwed from the opposite side, as is particularly shown in Fig. 6 can be clearly seen. The submerged oil electric motor 5 further comprises a rotor shaft 16 and a rotor 18 arranged on the rotor shaft 16 in a rotationally fixed manner. As shown, for example, in Fig. 7 and Fig. As shown in Figure 8, the rotor 18 is arranged radially inward within the stator 17. The rotor shaft 16 extends through the central passage 14 of the transverse wall and drives the pump element (not shown). In this exemplary embodiment, a plurality of radial piston pump elements are driven via the illustrated eccentric disc at the free end of the rotor shaft 16. The submerged-oil electric motor 5 is connected to a power source via a wiring (not shown in detail) in order to rotate the rotor shaft 16 in a conventional manner.

[0029] A thickened fastening region 20 is formed on the housing base body 2a, which is located next to the return opening 9 as viewed in the circumferential direction of the cylindrical interior 4. In this exemplary embodiment, the fastening region 20 has two fastening elements 11 designed as bores. The bores 11 each have an internal thread 12, which is provided for fastening a channel element 100 according to the invention, as will be explained in more detail below.

[0030] During operation of the pump unit 1, the submerged oil electric motor 5 is supplied with power, so that the rotor shaft 16 is set in rotation and drives at least one (not shown) pump element. As a result, an almost continuous volume flow of hydraulic oil with the achievable hydraulic power is directed through the pressure channel opening 7 and the pressure channel 8 to the hydraulic system. In this case, the oil level S of hydraulic oil in the oil reservoir T drops slightly, as is exemplified in Fig. 7 and Fig. 8 for a horizontal operating position of the pump unit 1. The returning hydraulic oil of the hydraulic system is returned via the return channel 8 and the return opening 9 into the interior 4 and thus the oil reservoir T in the circuit. As in Fig. As shown in Figure 8, when the pump unit 1 is operating horizontally, the return opening 9 is located above the oil level S in the oil reservoir T, so that without a channel element 100 according to the invention—which is described in detail below—the oil would escape into the atmosphere. In this case, the returning hydraulic oil would foam heavily, which could, for example, cause undissolved air to be sucked in by the pump element.

[0031] In order to prevent foaming of the returning hydraulic oil, the pump unit 1 according to the invention has the channel element 100 according to the invention, which is described in detail in the Fig. 9 to 14. The channel element 100 is made of glass fiber reinforced polyamide in this embodiment. The channel element 100 has a channel element inlet 101 with a central axis ME and a channel element outlet 102 with a central axis MA. The channel element inlet 101 and the channel element outlet 102 are connected to one another via a deflection section 103. The deflection section 103 is designed such that the central axis ME of the channel element inlet 101 is not parallel to the central axis MA of the channel element outlet 102. Rather, the central axis ME of the channel element inlet 101 runs approximately perpendicular to the central axis MA of the channel element outlet MA, as shown, for example, in Fig. 9 recognizable.

[0032] The deflection section 103 of the channel element 100 has a partially open side 104 which, when the channel element 100 is installed in the housing 2 of the pump unit 1, rests against the inner wall 10 of the housing 2 or the housing base body 2a, cf. Fig. 7 and Fig. 8. The deflection section 103 is designed such that the shape of the open side 104 follows the shape of the inner wall 10 of the housing base body 2a. To secure the channel element 100 to the housing 2 or to the fastening area 20 of the housing base body 2a, the channel element 100 has two fastening means 105 designed as pins. The pins 105 each have a plurality of locking means 106 on their outer circumference. As shown in Fig. 9, the pins 105 extend essentially parallel to the central axis ME of the channel element inlet 101 in the direction of the channel element inlet 101.

[0033] Furthermore, the channel element 100 has two disassembly means 107. The disassembly means 107 are designed as projections, each with an opening 108. As shown in Fig. As shown in Figure 12, the projections 107 extend parallel to the pins 105 in the direction opposite to the channel element inlet 101.

[0034] To assemble the channel element 100, the pins 105 are inserted into the holes 12 of the fastening area 20 of the housing base body 2a. The locking means 106 of the pins 105 engage the threads of the internal threads 12 of the holes 11, so that the channel element can be secured in the interior space 4 of the housing 2. The return opening 9 is connected to the channel element inlet 101. The partially open side 104 of the channel element 100 rests against the inner wall 10 of the housing base body 2a. As shown in Fig. 5, the channel element outlet 102 is offset by approximately 115° relative to the return opening 9 in the circumferential direction of the interior space.

[0035] When installed, the channel element 100 forms a line for the returning hydraulic oil. As shown in Fig. 7 and Fig. 8, the channel element outlet 102 is spaced from the connection area 3 such that the channel element outlet 102 is below the oil level S in the oil reservoir T that occurs during horizontal operation of the pump unit 1. The returning hydraulic oil does not exit through the return opening 9, but is guided through the channel element 100 and exits through the channel element outlet 102 below the oil level S. Thus, the returning hydraulic oil cannot foam. Furthermore, the returning hydraulic oil does not exit essentially in the direction of the central axis MR of the return opening 9, but essentially in the direction of the central axis MA of the channel element outlet 102. Since the channel element outlet 102 rests against the inner wall 10 of the housing base body 2a, the returning hydraulic oil flows along the cylindrical inner wall 10, as indicated by the arrow in Fig. 5. This improves the mixing of the returning hydraulic oil with the hydraulic oil present in the oil reservoir T, resulting in better overall thermal performance. The returning hydraulic oil is also cooled more effectively, as it is guided along the inner wall 10. Furthermore, this arrangement effectively prevents the returning and already heated hydraulic oil from being directly sucked back into the pump element.

[0036] To disassemble the channel element 100, the housing cover 2b of the housing 2 of the pump unit 1 is first removed. Depending on the design of the pump unit 1, it may also be necessary to remove the bearing plate 19 in order to disassemble the channel element 100. A suitable tool is then inserted into the openings 108 of the projections 107 of the channel element 100. For this purpose, the tool can, for example, have two hooks that engage in openings 108. A lifting force is applied via the tool, so that the pins 105 are pulled out of the bores 11. In the process, the locking means 106 are released from the threads of the internal thread 12. As soon as the last locking means 106 of the respective pin 105 no longer engages the internal thread 12, the channel element 100 can be removed from the housing 2 or the housing base body 2a.

[0037] In the Fig. Figures 15 to 18 show a pump unit 110 according to a second embodiment, not part of the invention. The parts of the pump unit 110 according to the second embodiment that correspond to the parts of the pump unit 1 according to the first embodiment are provided with identical reference numerals. In this regard, reference is made to the above explanations; only the structural differences between the two embodiments will be described below.

[0038] The pump unit 110 has a channel element 111, which consists of a guide part 112 and a cover part 113. The guide part 112 is formed in one piece with the housing 2 or the housing base body 2a, as shown in Fig. 17 and Fig. 18 can be seen. In this exemplary embodiment, the housing 2 is also an aluminum die-cast part, but can also be designed as an aluminum permanent mold casting. A cover part 113 is placed onto the guide part 112 via a detachable connection. In this exemplary embodiment, the detachable connection is a screw connection consisting of three screws 114, which engage through corresponding openings in the cover part 113 and are screwed into corresponding bores 115 in the housing base body 2a. The returning hydraulic oil is guided through the return channel 8 and enters the channel element 111 via the return bore 9 and the channel inlet 101. Here, the returning hydraulic oil is deflected by the guide part 112 and the cover part 113 so that it exits at the channel outlet 102 into the interior 4 of the housing 2, spaced from the connection area 3.This ensures, particularly in the horizontal operating mode of the pump unit 110, that the returning hydraulic oil does not escape into the atmosphere.

[0039] The housing base body 2a of the pump unit 110 is, in this embodiment, a die-cast aluminum part, with the guide part 112 and the areas receiving the bores 115 being directly formed. As can be seen in particular in Fig. As can be seen in Figure 18, the guide part 112 is formed together with a part of the stator retaining collar 15. The channel element 111 according to the second embodiment is particularly pressure-resistant and has high chemical resistance. List of reference symbols 1, 110 pump unit 2 housing base bodies 2a Housing cover 2b Housing cover 3 Connection area 4 Interior 5 submerged oil electric motor 6 pressure channels 7 Pressure channel opening 8 Return channel 9 Return opening 10 Interior wall 11 Fastening element / hole 12 Anchoring structure / internal thread 13 Cross wall 14 passage 15 Stator retaining collar 16 Rotor shaft 17 Stator 18 Rotor 19 Bearing shield 20 Mounting area 100, 111 channel element 101 Duct element inlet 102 Duct element outlet 103 Deflection section 104 open page 105 Fasteners / Tenons 106 locking element 107 Dismantling tool / projection 108 Opening 112 Leading section 113 Cover part 114 Screw 115 bore T Oil reservoir S Oil level MP center axis of the pump unit MR center axis of the return opening ME center axis of the channel element inlet MA center axis of the duct element outlet List of reference symbols 1, 110 pump unit 2 housing base bodies 2a Housing cover 2b Housing cover 3 Connection area 4 Interior 5 submerged oil electric motor 6 pressure channels 7 Pressure channel opening 8 Return channel 9 Return opening 10 Interior wall 11 Fastening element / hole 12 Anchoring structure / internal thread 13 Cross wall 14 passage 15 Stator retaining collar 16 Rotor shaft 17 Stator 18 Rotor 19 Bearing shield 20 Mounting area 100, 111 channel element 101 Duct element inlet 102 Duct element outlet 103 Deflection section 104 open page 105 Fasteners / Tenons 106 locking element 107 Dismantling tool / projection 108 Opening 112 Leading section 113 Cover part 114 Screw 115 bore T Oil reservoir S Oil level MP center axis of the pump unit MR center axis of the return opening ME center axis of the channel element inlet MA center axis of the duct element outlet

Claims

[1] Pump unit (1, 110) for a hydraulic system with a housing (2) and a connection area (3), wherein the housing (2) defines an interior space (4), wherein the interior space (4) is substantially cylindrical and at least partially forms an oil reservoir (T) that can be filled with hydraulic oil; and at least one pump element and at least one sub-oil electric motor (5) driving the pump element are arranged in the interior (4); wherein the connection area (3) has a pressure channel (6) with a pressure channel opening (7) and a return channel (8), wherein the pressure channel opening (7) is connected to the pump element and the return channel (8) opens into the interior (4) via a return opening (9), wherein the pump unit (1) has a channel element (100, 111) arranged in the interior (4) with a channel element inlet (101) and a channel element outlet (102), wherein the channel element (100) is formed separately from the housing (2), wherein the channel element inlet (101) is connected to the return opening (9), and the channel element outlet (102) is spaced from the connection area (3) such that the channel element outlet (102) projects into the interior space (4) below an oil level (S) in the oil reservoir (T) which is established during operation of the pump unit (1), wherein the channel element outlet (102) is offset by at least 45° to 120° relative to the return opening (9) in the circumferential direction of the interior space (4), and the central axis (MA) of the channel element outlet (102) is not parallel to the central axis (MR) of the return opening (9), and wherein the housing (2) has at least one fastening element (11), wherein the channel element (100) has at least one fastening means (105) fixed to the fastening element (11). [2] Pump unit (1, 110) according to claim 1, characterized bythat the central axis (MA) of the channel element outlet (102) runs substantially perpendicular to the central axis (MR) of the return opening (9). [3] Pump unit (1) according to one of the preceding claims, characterized by that the channel element (100) has a deflection section (103) connecting the channel element inlet (101) and the channel element outlet (102), wherein the deflection section (103) has an at least partially open side (104). [4] Pump unit (1) according to claim 3, characterized by that the open side (104) rests against an inner wall (10) of the housing (2). [5] Pump unit (1) according to one of the preceding claims, characterized by that the fastening element (11) is a bore with an anchoring structure (12), and the fastening means (105) is a pin with locking elements (106), wherein the anchoring structure (12) is in particular an internal thread. [6] Pump unit (1) according to one of the preceding claims, characterized by that the channel element (100) has at least one disassembly means (107), wherein the disassembly means (107) is in particular a projection with preferably an opening (108). [7] Pump unit (1) according to one of the preceding claims, characterized by that the channel element (100) is made of a plastic, in particular of a glass fiber reinforced polyamide. [8] Pump unit (1) according to one of the preceding claims, characterized by that the housing (2) is a cast part, in particular an aluminum die-cast part. [9] Channel element (100) for use with a pump unit (1) for a hydraulic system, wherein the pump unit (1) has a housing (2) and a connection area (3), wherein the housing (2) defines an interior space (4), wherein the interior space (4) is substantially cylindrical and at least partially forms an oil reservoir (T) that can be filled with hydraulic oil, wherein at least one pump element and at least one submerged oil electric motor (5) driving the pump element are arranged in the interior space (4), wherein the connection area (3) has a pressure channel (6) with a pressure channel opening (7) and a return channel (8), wherein the pressure channel opening (7) is connected to the pump element and the return channel (8) opens into the interior space (4) via a return opening (9), wherein the channel element (100) has a channel element inlet (101), a channel element outlet (102) offset by at least 45° to 120° relative to the return opening (9) in the circumferential direction of the interior space (4), and a deflection section (103) connecting the channel element inlet (101) and the channel element outlet (102), wherein the central axis (MA) of the channel element outlet (102) is not parallel to the central axis (ME) of the channel element inlet (101), wherein the channel element inlet (101) is connected to the return opening (9), and the channel element outlet (102) is spaced from the connection area (3) such that the channel element outlet (102) opens into the interior space (4) below an oil level (S) in the oil reservoir (T) which is established during operation of the pump unit (1), and wherein the channel element (100) has at least one fastening means (105) for fastening the channel element (100) to a housing (2) of the pump unit (1). [10] Channel element (100) according to claim 9, characterized by that the central axis (MA) of the channel element outlet (102) runs substantially perpendicular to the central axis (ME) of the channel element inlet (101). [11] Channel element (100) according to claim 9 or 10, characterized by that the deflection section (103) has an at least partially open side (104). [12] Channel element (100) according to one of the preceding claims 9 to 11, characterized by that the fastening means (105) is in particular a pin with locking elements (106). [13] Channel element (100) according to one of the preceding claims 9 to 12, characterized by that the channel element (100) has at least one disassembly means (107), wherein the disassembly means (107) is in particular a projection with preferably an opening (108). [14] Channel element (100) according to one of the preceding claims 9 to 13, characterized bythat the channel element (100) is made of a plastic, in particular of a glass fiber reinforced polyamide.

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