Pump device for a hydraulic system of a motor vehicle, hydraulic system

Abstract

The invention relates to a pump device (1) for a hydraulic system (2) of a motor vehicle, comprising an electric drive motor (3), a delivery screw (15) coupled to the drive motor (3), and a cylindrical housing (14) in which the delivery screw (15) is rotatably mounted, wherein the delivery screw (15) forms, together with the housing (14), delivery chambers (16) which move from a fluid inlet to a fluid outlet of the housing (14) upon rotation of the delivery screw (15). According to the invention, a central longitudinal axis (19) of the delivery screw (15) is arranged eccentrically in relation to a central longitudinal axis (18) of the housing (14), the housing (14) has, as an outer screw (13), a screw structure on its inner face facing the delivery screw (15), wherein portions of the delivery screw (15) and of the outer screw (13) mesh with one another in order to form the delivery chambers (16), and the outer screw (13) is mounted rotatably about the central longitudinal axis (18).

Description

[0001] The invention relates to a pump device for a hydraulic system of a motor vehicle, comprising an electric drive motor and a cylindrical housing in which the pump spindle is rotatably mounted, wherein the pump spindle together with the housing forms pumping chambers which move from a fluid inlet to a fluid outlet of the housing by means of a rotary movement of the pump spindle.

[0002] Furthermore, the invention relates to a hydraulic system for a motor vehicle, in particular a lubrication system, coolant system, fuel system, exhaust aftertreatment system or the like, with at least one pump device as described above.

[0003] Pump devices of the type mentioned above are known from the prior art. For example, German patent application DE 10 2017 210 770 A1 discloses a pump device of this type, designed as a screw pump. The known pump device has two screw spindles arranged parallel to each other, which interlock and, together with the surrounding housing, each form pumping chambers for conveying the fluid. Another pump device of this type is known from German patent application JP 2002-257053 A. Further pump devices with screw spindles are known from German patent applications US 6,499,966 B1 and US 2020 / 0056462 A1. Further pump devices are known from patent EP 1 888 943 B1, publications WO 2008 / 096963 A1, US 2010 / 092317 A1, JP 6 585382 B2, US 4 482 305 A and FR 2 451 474 A1.

[0004] The present invention is based on the objective of creating an improved pump device that has a reduced number of parts at a high delivery volume and can be integrated into a hydraulic system in a space-saving manner.

[0005] The problem underlying the invention is solved by a pump device with the features of claim 1. This device is characterized in that a rotational axis of the conveying spindle is arranged eccentrically to a central longitudinal axis of the housing, the housing having a spindle structure on its inner surface facing the conveying spindle as an outer spindle, wherein the conveying spindle and the outer spindle interlock to form the conveying chambers, and the outer spindle or the housing is rotatably mounted about the central longitudinal axis. The pump device thus has two conveying spindles, one of which forms an inner spindle and the other an outer spindle, which interact to form the conveying chambers between them.Because both the housing and the feed spindle are rotatably mounted and are in mesh with each other, it is sufficient to drive either the feed spindle or the housing to operate the pump device. The rotary motion of one element is transmitted to the other element via the interlocking spindle structures. The interlocking spindles of the pump device according to the invention enable a high displacement volume or high delivery rate to be achieved in a small installation space.

[0006] According to a preferred embodiment of the invention, the drive motor is connected either to the outer spindle or to the conveying spindle. This provides a simple mechanical solution for driving the pump device. For example, the drive motor of the pump motor is connected directly or via a transmission gear to the conveying spindle or the outer spindle in order to transmit the torque from the drive motor to the pump device.

[0007] According to a preferred embodiment of the invention, the outer spindle is designed as the internal rotor of the drive motor. Thus, the outer spindle itself forms a drive shaft of the drive motor and is therefore integrally integrated into the drive motor. This allows the drive motor to directly drive the outer spindle of the pump device and to be positioned particularly close to the conveying spindle and the outer spindle, thereby saving further installation space. In addition, mechanical losses between the drive motor and the outer spindle are minimized.

[0008] Particularly preferred is a stator associated with the inner rotor held in a stator housing, wherein the outer spindle and / or the feed spindle are rotatably mounted on the stator housing. The stator housing thus forms a pump housing of the pump device, in which the essential components of the pump device, namely the outer spindle, feed spindle and drive motor, are at least substantially arranged and protected from external influences.

[0009] Furthermore, it is preferably provided that the stator housing has a bearing plate at each end face for the rotatable mounting of the conveying spindle. The respective bearing plate extends, in particular, over the respective end face of the stator housing, so that the bearing plate axially covers both the conveying spindle and the outer spindle. By mounting the conveying spindle on the bearing plate, it can be securely positioned and rotatably rotated within the stator housing in an arrangement eccentric to the outer spindle. The conveying spindle is set into its own rotation about its central longitudinal axis or axis of rotation, which is eccentric to the central longitudinal axis of the housing, by a rotational movement of the outer spindle.

[0010] Furthermore, it is preferably provided that the conveying spindle is mounted in the respective bearing plate by means of a sliding bearing. The sliding bearing ensures a particularly compact design of the pump device, which is also cost-effective due to the elimination of separate rolling element bearings. According to an alternative embodiment of the invention, the conveying spindle is mounted by a single rolling element bearing in the respective bearing plate to minimize friction losses.

[0011] At least one of the bearing shields is preferably formed separately from the stator housing and attached to it, for example by welding, bolting, and / or bonding. The bearing shield is particularly preferably positively connected to the stator housing, especially in the circumferential and / or radial direction, to ensure a permanently secure positioning of the bearing shield on the stator housing and thus a permanently secure positioning of the conveyor spindle in the outer spindle. Alternatively, at least one of the bearing shields is preferably formed integrally with the stator housing. This ensures a permanently secure connection between the bearing shield and the stator housing.

[0012] If the bearing shield is designed separately from the stator housing, it preferably forms at least one anti-rotation feature with the stator housing, which acts as a positive locking mechanism in the circumferential direction. This anti-rotation feature prevents the bearing shield from rotating relative to the stator housing, which would otherwise change the position of the feed spindle in the outer spindle. The anti-rotation feature is formed, in particular, by at least one axial projection of the bearing shield or the stator housing, which engages with at least one axial recess in the stator housing or the bearing shield. This reliably prevents unintentional rotation of the bearing shield and ensures unambiguous positioning of the bearing shield during assembly using simple means.

[0013] According to a preferred embodiment of the invention, the outer shell wall of the outer spindle forms a sliding bearing with an inner shell wall of the stator housing for the rotatable mounting of the outer spindle. The outer spindle, or rather the housing, is thus directly supported in the stator housing, resulting in a space-saving design for the pump assembly. Alternatively, at least one rolling element bearing is provided between the stator housing and the outer spindle to reduce friction losses. Depending on the available installation space and the desired delivery rate or dimensions of the pump assembly, either a sliding bearing or a rolling element bearing is selected.

[0014] Preferably, the stator housing extends axially beyond the stator in at least one direction. This makes the stator housing axially longer than the stator, ensuring a sufficiently long delivery path of the pump device through the outer spindle and delivery spindle within the stator housing, regardless of the drive motor's dimensions. Preferably, the outer spindle and inner spindle also extend axially beyond the drive motor and stator, respectively. In particular, the stator housing extends axially on both sides of the stator, providing connection ports on both sides of the drive motor for additional components of a hydraulic system, such as hydraulic lines, especially hydraulic hoses.

[0015] Preferably, the conveying spindle and the outer spindle are each designed as screw spindles, i.e., as screw outer spindles and screw inner spindles. This creates advantageous conveying chambers that ensure a high conveying volume during operation of the pump device.

[0016] Furthermore, it is preferably provided that the respective shield has one or more flow openings for the fluid to be pumped. This allows the fluid to enter and exit the pump device axially. This avoids flow losses that would otherwise be necessary, for example, due to deflections in radial entry directions. This further increases the efficiency of the pump device.

[0017] Furthermore, it is preferably provided that the outer spindle and the conveying spindle are designed such that their axial extent is at least 1.2 times longer than that of a conveying chamber formed between the outer and inner spindles. This ensures reliable fluid conveyance by the pumping device during operation. A reversal of the direction of rotation in the drive of the pumping device also achieves a reversal of the conveying direction, so that a reversal of the conveying direction is possible without special additional means by appropriately controlling the drive motor.

[0018] Furthermore, it is preferably provided that at least one seal and / or at least one leakage opening is formed between the outer shell wall of the outer spindle and the stator housing. The seal ensures that the fluid being pumped does not reach the drive motor and, for example, impair its function. However, if the drive motor itself is designed to be fluid-tight or moisture-tight, then preferably at least one leakage opening is formed between the outer shell wall and the stator housing, through which a portion of the fluid being pumped also reaches the drive motor and, for example, a control unit of the drive motor, in order to cool them during operation of the pumping device. This eliminates the need for separate cooling devices for the pumping device.

[0019] The hydraulic system according to the invention, comprising the features of claim 14, is characterized by the pump device being designed according to the invention. This results in the advantages already mentioned.

[0020] Further advantages and preferred features and combinations of features will become apparent in particular from the foregoing and from the claims. The invention will now be explained in more detail with reference to the drawings. To this end, we show... Figure 1 shows an advantageous pump device in a perspective view, Figure 2 shows the pump device in a perspective longitudinal section view, Figures 3A and 3B show the pump device in an axial top view without and with bearing cover, and Figures 4A and 4B show individual parts of the pump device in perspective views.

[0021] Figure 1Figure 1 shows a perspective view of an advantageous pump device 1 for a hydraulic system 2 (not shown in detail here), which is designed, for example, as a coolant system, lubricant system, or operating fluid system for a motor vehicle. The pump device 1 has a drive motor 3 configured to electrically drive a hydraulic pump 4. For this purpose, the drive motor 3 has a stator 5, which interacts with a rotor 6 arranged coaxially within the stator 5 and rotatably mounted, to drive the pump 4. The stator 5 has an annular yoke 7, from which several stator teeth 8 extend radially inwards towards the rotor 6, each stator tooth 8 being assigned a drive winding or part of a drive winding 9 of the drive motor 3.

[0022] Figure 2 The pump device 1 shows Figure 1in a perspective longitudinal section view. The stator teeth 8 terminate on their side facing away from the stator yoke 7 at or within a stator housing 10, so that the stator teeth 8 lie at least substantially outside the stator housing 10. The stator housing 10 is itself cylindrical and extends axially beyond the stator 5 at both of its end faces, so that the overall axial length of the stator 5 or the drive motor 3 is significantly smaller relative to the axial length of the stator housing 10.

[0023] The pump 4 is formed in the stator housing 10 and the rotor 6 of the drive motor 3 is arranged therein. The rotor 6 is rotatably mounted in the cylinder housing 10, in particular by means of a rolling element bearing, a sliding bearing or a hydrodynamic bearing.

[0024] The stator housing 10 has a receiving section 11 for receiving the rotor 6, which has an inner diameter that corresponds at least substantially to the outer diameter of the rotor 6 and / or the rolling element bearing supporting the rotor 6. The remainder of the stator housing 10 has an inner diameter that is smaller than the inner diameter of the receiving section 11. In particular, the stator housing 10 has a bearing section 12 on each of its end faces, which is designed to support a housing 14 of the pump 4 configured as an outer spindle 13.

[0025] The pump 4 has the aforementioned external spindle 13 and a conveying spindle 15, wherein the external spindle 13 is designed as a hollow shaft with an inwardly projecting spindle structure that interacts with the spindle structure of the conveying spindle 15 to form conveying chambers 16 for the fluid to be conveyed. Both the external spindle 13 and the conveying spindle 15 are designed as screw spindles and are rotatably mounted in the stator housing 10.

[0026] The outer spindle 13 is rotatably mounted directly in the stator housing 10, with the inner diameter of the stator housing 10 in the bearing sections 12 preferably corresponding at least substantially to the outer diameter of the outer shell wall of the outer spindle 13, thus ensuring advantageous sliding bearing between the outer spindle 13 and the stator housing 10 in the bearing sections 12. Between the bearing sections 12 lies, firstly, the receiving section 11 for the rotor 6, and secondly, the stator 10 has a larger outer diameter between the bearing sections 12, so that the outer spindle 13 does not bear against the stator housing 10 with its outer shell wall over its entire surface, or only in certain areas. The outer spindle 13, whose outer shell wall is circular, is advantageously rotatably mounted in the stator housing 10 by means of the sliding bearings 17.In particular, the outer spindle 13 is arranged coaxially to the stator housing 10 in the stator housing 10, so that the central longitudinal axis 18 of the outer spindle 13 and of the stator housing 10 are aligned or correspond to each other.

[0027] The conveying spindle 15 is arranged in the stator housing 10 such that the central longitudinal axis 19 of the conveying spindle 15 is parallel and eccentrically or radially offset to the central longitudinal axis 18. For supporting and positioning the conveying spindle, the stator housing 10 has a bearing plate 20 at each of its end faces. The bearing plates 20 are either formed integrally with the stator housing 10 or manufactured as separate components and are attached to the end faces of the stator housing 10, in particular by a form-fit and / or material-fit connection. Each bearing plate has an outer circular ring 21, the outer diameter of which corresponds in particular to the outer diameter of the stator housing 10 and which is arranged coaxially with the stator housing 10. Furthermore, the ring 21 carries a bearing 22 for the conveying spindle 15. The bearing 22 is connected to the ring 21, in particular integrally, by several struts 23 extending in particular radially.The bearing 22, for example, has a bearing pin 24 that sits in a bearing pin receptacle 25 located centrally in cross-section in one of the end faces of the conveyor spindle 15. If both bearing shields 20 are identical, the conveyor spindle 15 is thus held at each end face by a bearing pin 24 or pushed onto it and is thereby rotatably mounted on the bearing shield 20. The bearing pin or the bearing 22 is arranged eccentrically to the ring 21, so that the central longitudinal axis 19, as already mentioned, is offset from the central longitudinal axis 18 of the housing 14 and the stator housing 10.

[0028] Figures 3A and 3B Each of these figures shows an axial top view of the pumping device, wherein in Figure 3A the warehouse sign 20 was removed and in Figure 3B the bearing plate is mounted.

[0029] In particular Figure 3Ashows that the central longitudinal axes 19 and 18 are offset from each other, and that the spindle structures of the conveying spindle 15 and the external spindle 13 interlock.

[0030] In Figure 3B It is evident that the respective bearing shield 20 connects the ring 21 to the bearing 22 by means of several, in this case three, struts 23. In particular, the struts 23 are arranged or formed evenly distributed around the circumference of the bearing 22. This creates flow openings 26 between the struts 23, through which a fluid to be pumped can enter or exit the pump 4, depending on the pumping direction of the pump 4.

[0031] Figures 4A and 4B show individual parts of pump 4, namely the outer spindle 13 in Figure 4A and the feed spindle 15 in Figure 4B The feed spindle is 15 in this case. Figure 4BAccording to an alternative embodiment, the conveying spindle 15 itself has the bearing pins 24 at its end, so that the respective bearing 22 then has the bearing pin receptacle 25 in which the respective bearing pin 24 is rotatably mounted. As in Figures 4A and 4B As can be seen, the spindle structures of the external spindle 13 and the conveying spindle 15 are designed as screw spindles. Due to the eccentric arrangement of the central longitudinal axes 18, 19 of the two spindles, as particularly evident in Figure 3AAs shown, the outer spindle 13 and the conveying spindle 15 form the advantageous conveying chambers 16 between them. It is preferably provided that the maximum outer diameter of the conveying spindle 15 within the outer spindle 13 is smaller than the smallest inner diameter of the outer spindle 13, so that rotation of the conveying spindle 15 within the outer spindle 13 is reliably ensured at all times. Because the spindle structures are designed to form the pressure chambers 16, and because of the offset arrangement of the central longitudinal axes, the spindle structures are partially engaged with each other. This ensures that at least one projection of the spindle structure of the conveying spindle 15 is always engaged in a recess of the spindle structure of the outer spindle 13. As a result, the spindles are always positively coupled or connected to each other in the direction of rotation, and the conveying chambers 16 are reliably formed.

[0032] The rotor 6 is rotationally fixed to the outer spindle 13, so that when the drive motor 3 is activated, the rotor 6 drives the outer spindle 13 or applies a torque to it. The interlocking spindle structures also drive the internal conveying spindle 15, causing the conveying chambers 16, which are formed between the conveying spindles 15 and the outer spindle 13, to move from one end face to the opposite end face of the stator housing 10, thereby conveying fluid from one end face to the other.

[0033] Because the stator housing 10 projects axially from the drive motor 3 in both directions, it can, for example, be easily inserted into hydraulic lines or hoses from both sides or end-to-end to establish the hydraulic connection to the hydraulic system. Depending on the direction of rotation of the drive motor, the fluid is then conveyed from one direction to the other, with one end shield 20 serving as the inlet and the other end shield 20 as the pressure-side outlet 4.

[0034] To ensure the safe conveyance of the fluid from the inlet to the outlet, the length L of the pump 4 or of the outer spindle 13 and the conveying spindle 15 is at least 1.2 times longer than the conveying chamber 16 formed between the spindles.

[0035] If the bearing shields 20 are not formed in one piece but separately on the stator housing 10, thus simplifying the assembly of the pump device 1, the bearing shields 20 are positively locked to the stator housing, in particular by means of an anti-rotation device 28, to reliably prevent rotation and thus any change in the eccentric position of the conveying spindle 15 relative to the outer spindle 13. The respective anti-rotation device 28 is ensured, in particular, by a positive-locking connection between the bearing shield 20 and the stator housing 10 acting in the circumferential direction. For this purpose, for example, an axial projection of the bearing shield 20 can be arranged in a complementary end-face recess of the stator housing 10, or is arranged, to prevent rotation of the bearing shield 20 relative to the stator housing 10. Optionally, the anti-rotation device 28 has several such projections and thus cooperating receiving recesses.Particularly preferred is one of the bearing shields formed in one piece with the stator housing 10 and the other bearing shield 20 as a separate component, in order to ensure easy assembly of the pump device 1 with as few individual parts as possible.

[0036] Preferably, at least one sealing element 29 is arranged between the outer spindle 13 and the stator housing 10, in particular adjacent to the bearing sections 12, so that the fluid to be pumped cannot enter the area of ​​the stator housing 10 in which the drive motor 3 or the rotor 6 is located. The respective sealing element 29 is preferably designed as a ring seal or circumferential seal, which bears against the outer shell wall of the outer spindle 13 on one side and against the inner shell wall or side of the stator housing 10 on the other.

[0037] According to an alternative embodiment, a leakage opening or leakage gap 30 is formed between the outer spindle 13 and the stator housing 10 in the area of ​​the bearing sections 12, for example by an axially extending groove formed in the stator housing 10 or the outer spindle 13, which allows a leakage flow of the fluid into the area of ​​the stator housing 10 between the bearing sections 12 and which is then used to cool the drive motor 3, in particular the rotor 6 or a control device or unit optionally arranged in the area of ​​the drive motor 3, during the operation of the pump device 1. Figure 2 The embodiment with the seal 29 is shown in the plane of the image to the left of the drive motor 3 and the embodiment with the leakage gap 30 to the right of the drive motor for better understanding of both embodiments. Reference symbol list

[0038] 1 Pump device 2 Hydraulic system 3 Drive motor 4 Pump 5 Stator 6 Rotor 7 Stator yoke 8 Stator tooth 9 Drive winding 10 Stator housing 11 Mounting section 12 Bearing section 13 Outer spindle 14 Housing 15 Conveyor spindle 16 Conveyor chamber 17 Plain bearing 18 Central longitudinal axis 19 Central longitudinal axis 20 Bearing shield 21 Ring 22 Bearing 23 Strut 24 Bearing bolt 25 Bearing bolt receptacle 26 Flow opening 28 Rotation lock 29 Seal 30 Leakage gap

Claims

1. Pump device (1) for a hydraulic system (2) of a motor vehicle, comprising an electric drive motor (3), and a cylindrical housing (14) in which the conveying screw (15) is rotatably mounted, wherein the conveying screw (15) together with the housing (14) forms conveying chambers (16) which move from a fluid inlet to a fluid outlet of the housing (14) by a rotary movement of the conveying screw (15), wherein a central longitudinal axis (19) of the conveying screw (15) is arranged eccentrically and parallel to a central longitudinal axis (18) of the housing (14), with the housing (14) having a screw structure on its inner face facing the conveying screw (15) as an outer screw (13), wherein the outer screw (13) is rotatably mounted about the central longitudinal axis (18) of the housing, wherein the drive motor (3) is connected either to the outer screw (13) or to the conveying screw (15), and wherein the conveying screw (15) and the outer screw (13) mutually engage in parts, so that they form the conveying chambers (16) and so that, by means of mutually engaging screw structures, a rotary movement of the conveying screw (15) is transmitted to the outer screw (13) or a rotary movement of the outer screw (13) is transmitted to the conveying screw (15).

2. Pump device according to claim 1, characterized in that the drive motor (3) is connected to the conveying screw (15) or to the outer screw (13) for conjoint rotation.

3. Pump device according to either of the preceding claims, characterized in that the outer screw (13) is designed as an inner rotor of the drive motor (3).

4. Pump device according to claim 3, characterized in that a stator (5) associated with the inner rotor is held on a stator housing (10), wherein the outer screw (13) and / or the conveying screw (15) are rotatably mounted in the stator housing (10).

5. Pump device according to claim 4, characterized in that the stator housing (10) has a bearing plate (20) on each end face for rotatable mounting of the conveying screw (15).

6. Pump device according to claim 5, characterized in that the conveying screw (15) is mounted in a plain bearing in the relevant bearing plate (20).

7. Pump device according to either claim 5 or claim 6, characterized in that at least one of the bearing plates (20) is formed separately from or integrally with the stator housing (10).

8. Pump device according to claim 7, characterized in that the separately formed bearing plate (20) forms at least one form-fitting anti-rotation device (28) with the stator housing (10).

9. Pump device according to any of claims 4 to 8, characterized in that a casing outer wall of the outer screw (13) together with a casing inner wall of the stator housing (10) forms a plain bearing (17) for the rotatable mounting of the outer screw (13).

10. Pump device according to any of claims 4 to 9, characterized in that the stator housing (10) extends axially beyond the stator (5) in at least one direction.

11. Pump device according to claim 5, characterized in that the relevant bearing plate (20) has one or more throughflow openings (26) for the fluid to be conveyed.

12. Pump device according to any of the preceding claims, characterized in that the outer screw (13) and the conveying screw (15) are designed such that their axial extension is at least 1.2 times longer than a conveying chamber (16) formed between the outer screw (13) and the conveying screw (15).

13. Pump device according to claim 9, characterized in that between the casing outer wall of the outer screw (13) and the stator housing (10), at least one seal (29) and / or at least one leakage opening (30) is formed.

14. Hydraulic system (2) for a motor vehicle, in particular a lubricant system, coolant system, fuel system, exhaust gas aftertreatment system, equipment system, comprising at least one pump device (1) according to any of claims 1 to 13.

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