WO2023131712A1

WO2023131712A1 - Motor-pump unit, in particular for a high-pressure cleaning appliance

Info

Publication number: WO2023131712A1
Application number: PCT/EP2023/050348
Authority: WO
Inventors: Thomas Maier; Wolfgang Müller; Holger PFANZ; Markus Bauer
Original assignee: Alfred Kärcher SE & Co. KG
Priority date: 2022-01-10
Filing date: 2023-01-09
Publication date: 2023-07-13
Also published as: DE102022100388A1; CN118234945A

Abstract

The invention relates to a motor-pump unit (11), in particular for a high-pressure cleaning appliance having a motor (12), having a gear mechanism (16), which is driven by the motor (12) and has an output shaft (17), which rotates about a longitudinal axis (32), having a swash plate (18), which is arranged on the output shaft (17) for conjoint rotation, having a piston pump (21), which is assigned to the swash plate (18) and comprises a plurality of pistons (22), having a first axial bearing (33), which is arranged between the swash plate (18) and the piston pump (21), and having a connection housing (44), which can connect the motor (12) and the piston pump (21), wherein the swash plate (18) is mounted for rotation in relation to the connection housing (44) by way of a second axial bearing (45).

Description

Motor pump unit, in particular for a high-pressure cleaning device

The invention relates to a motor pump unit, in particular for a high-pressure cleaning device, according to the preamble of claim 1.

A high-pressure cleaning device is known from DE 10 2007 017 970 A1. This high-pressure cleaning device includes a device housing that accommodates a motor pump unit. This motor-pump unit includes an electric motor as well as a gearbox connected thereto and also a swash plate, through which several pistons of a piston pump are driven in the axial direction of the high-pressure cleaning device. The pistons successively dip into a pump chamber of the piston pump through this swash plate. These pump chambers are each connected to a suction line via a suction valve and to a pressure line via a pressure valve.

The invention is based on the object of proposing a motor pump unit, in particular for a high-pressure cleaning device, with an increased service life.

This object is achieved by a motor-pump unit, in particular for a high-pressure cleaning device, with a motor that drives a transmission that includes an output shaft that rotates about its longitudinal axis, and with a swash plate that is non-rotatably arranged on the output shaft, and with a piston pump assigned to the output shaft, comprising a plurality of pistons and having a first thrust bearing arranged between the swash plate and the piston pump, in which the swash plate is rotatably supported in a connection housing between the motor and the piston pump by a second thrust bearing.

Surprisingly, it has been found that an increased service life can be achieved by arranging a first axial bearing between the swash plate and the piston of the piston pump and a second axial bearing between the swash plate and the connection housing. through the The piston pump transmits an axial load to the swash plate via the first axial bearing, but also a radial load that is reduced compared to the axial load. This radial load, which is low in relation to the axial load, can be absorbed by the second axial bearing in order to support the swash plate in the connection housing in a rotating manner. By arranging the second axial bearing between the swash plate and the connection housing, an improved load transfer and thus an increased service life can be achieved.

It is preferably provided that the first and/or the second axial bearing is designed as an axial grooved ball bearing. These axial deep groove ball bearings can have a particularly long service life and can be adapted to special load cases.

Furthermore, it is preferably provided that the swash plate comprises a first connection point facing the piston pump, which has a support surface for the first axial bearing, which is inclined relative to the longitudinal axis of the output shaft of the transmission, and opposite on the swash plate a second connection point facing the transmission comprises for the second thrust bearing, which has a support surface which is aligned radially to the longitudinal axis. As a result, the previous installation space for connecting the swash plate to the output shaft of the transmission on the one hand and for connecting the swash plate to the piston pump on the other hand can be retained.

The first and second connection points of the swash plate advantageously each comprise an annular collar which is provided radially on the inside of the support surface. As a result, a simple fixing of the position of the axial bearing relative to the swash plate and simple assembly can be made possible.

Advantageously, the axial bearings have two opposing thrust washers, each with an inner track, in particular a track groove, for balls. In particular, the pressure disks have a flat and radially aligned pressure surface on the outside. The balls are preferably guided through a cage. Furthermore, it is preferably provided that the first axial bearing has a pitch circle for balls, which corresponds to a pitch circle of the pistons of the piston pump or is located radially outside of the pitch circle of the pistons of the piston pump. As a result, favorable power conditions can be created for driving the piston pump.

Furthermore, it is preferably provided that the second axial bearing includes a pitch circle for guiding the balls, which is the same size as or larger than the pitch circle of the balls of the first axial bearing. This in turn favors a load transfer from the swash plate to the connection housing.

According to a preferred embodiment, it is provided that the outer contact surfaces or annular surfaces of the thrust washers of the thrust bearings are of the same size. As a result, a structurally simple configuration of the axial bearings can be made possible. It may only be necessary to adjust the outer diameter or the pitch circle diameter of the axial bearing. Advantageously, the diameter of the second axial bearing is larger than that of the first axial bearing.

According to an alternative embodiment of the invention, it can be provided that the first axial bearing, which is provided between the swash plate and the piston pump, has two thrust washers that differ in size, with an outer contact surface of one thrust washer, which faces the piston pump, being wider than that pointing to the swash plate contact surface or annular surface of the thrust washer is formed. The outer diameter of the two thrust washers is preferably the same, but the inner diameter is different. As a result, different sizes of the piston pump can be driven by means of an embodiment of the first axial bearing.

The thrust washer of the first and/or second axial bearing preferably has an osculation which is less than or equal to 0.53, preferably less than 0.525, at a ratio of a radius of the raceway to a diameter of the ball. This allows for improved leadership of the balls in the Raceway of the thrust washer done. The osculation determines the size of the contact surface between the ball and the raceway of the thrust washer. The osculation can also determine the size of the rolling friction. The smaller the osculation selected, the greater the proportion of sliding when the balls roll.

It is preferably provided that each thrust washer of the first and/or second axial bearing has an osculation which, with a ratio of a radius of the raceway to a diameter of the ball, is in a range between 0.49 and 0.53, preferably between 0.50 and 0.525, more preferably between 0.51 and 0.52. With such a ratio, a sufficient radial load can in particular still be absorbed, which acts on the first and/or second axial bearing in the present installation situation.

Furthermore, the depth of the track in the thrust washer of the first and/or second thrust bearing for the balls can be equal to or less than 2.5 mm, preferably in a range between 0.5 and 1.2 mm.

Advantageously, for the first and/or second axial bearing, the balls with a diameter in a range from 6.0 to 6.5 mm, in particular 6.35 mm or in a range from 7.2 to 7.8 mm, in particular 7 5 mm formed. As a result, particularly long service lives can be achieved.

Advantageously, the first and/or second thrust bearing comprises a cage made of plastic material. A polyamide is advantageously provided as the plastic. In particular, a glass fiber reinforced polyamide 6.6 can be provided.

The first and/or second thrust bearing can advantageously be used for an axial load in a range from 2,500 to 3,500 N (Newtons) and a radial load in a range from 250 to 600 N, preferably for a speed range from 3,000 to 7,000 rpm (revolutions per minute). be designed. The invention and other advantageous embodiments and developments thereof are described and explained in more detail below with reference to the examples shown in the drawings. The features to be found in the description and the drawings can be used according to the invention individually or collectively in any combination. Show it:

Figure 1: a schematic view of a motor pump unit,

Figure 2: a schematic sectional view of a bearing of a swash plate,

Figure 3: a schematic view of an axial bearing,

Figure 4: a schematic sectional view along the line III-III in Figure 3,

Figure 5: a schematic sectional view of a thrust washer with a ball of the axial bearing shown schematically,

FIG. 6: a schematic plan view of a cage of the axial bearing according to FIG. 3,

Figure 7: a schematic sectional view along the line VI-VI in Figure 6,

FIG. 8: a schematic sectional view of an alternative embodiment of the axial bearing to FIG. 3 and

Figure 9: a schematic sectional view of a further alternative embodiment of the axial bearing to Figure 3.

In Figure 1, a motor pump unit 11 is shown schematically. This

Motor pump unit 11 can be provided for a high-pressure cleaning device be. Such high-pressure cleaning devices make it possible to generate a pressurized cleaning liquid, such as water, and in particular to dispense it onto a surface to be cleaned via a hose and, for example, a spray lance or nozzle. This motor-pump unit 11 includes a motor 12 , in particular an electric motor, which drives a drive shaft 14 . The engine 12 is connected to a transmission 16 . The drive shaft 14 is provided on the input side of the transmission 16 . An output shaft 17 is provided on the output side of the transmission 16 . The transmission 16 drives a swash plate 18 in particular via the output shaft 17 . This swash plate 18 is directed towards a piston pump 21 . This piston pump 21 has a plurality of pistons 22 positioned on a pitch circle. These pistons 22 are reciprocally displaceable in the axial direction of the motor pump end unit 11 . These are each immersed in a cubic capacity 23 of a pump head 24 . The displacements 23 are each connected to a suction line 26 via a suction valve 25 and to a pressure line 28 via a pressure valve 27 . A further suction line 29 for connection to a suction line for a cleaning liquid and/or chemical is advantageously provided on the pump head 24 .

FIG. 2 shows a schematic sectional view of a partial area of the motor-pump unit 11 to show a mounting of the swash plate 18 .

The drive shaft 14 of the motor 12 is guided in rotation about its longitudinal axis 32 by a radial bearing 31, in particular a radial deep groove ball bearing. The drive shaft 14 drives the transmission 16 . The output shaft 17 is provided on the transmission 16 on the output side. The swash plate 18 is held in a rotationally fixed manner on this output shaft 17 , so that the swash plate 18 is driven in rotation by the output shaft 17 . A first axial bearing 33 is provided between the piston pump 21 and the swash plate 18 . This axial bearing 33 comprises two thrust washers 37 between which balls 38 are guided in a radially rotating manner in each case in a raceway 39 . The balls 38 of the thrust bearing 33 are preferably held and guided in a cage 41 . The swash plate 18 includes a first connection point 36 for receiving the first axial bearing 33. The connection point 36 includes a support surface 34, which is aligned inclined to the longitudinal axis 32. This support surface 34 has an annular collar 35 lying radially on the inside. The thrust washer 37 of the axial bearing 33 rests with an outer contact surface 42 on the support surface 34 . An inner edge of the thrust washer 37 engages the annular collar 35 . This provides a central support for the axial bearing 33 and an axial support for the swash plate 18 . The opposite thrust washer 37 of the first axial bearing 33 rests against the end faces of the pistons 22 . This first axial bearing 33 significantly reduces the friction when the swash plate 18 is driven in rotation in relation to the piston 22 of the piston pump 21 which can be moved in and out axially.

A connection housing 44 is provided between the piston pump 21 and the motor 12 . This connection housing 44 can also be part of the housing of the motor 12 . The swash plate 18 is rotatably mounted with respect to the connection housing 44 by a second axial bearing 45 . This second axial bearing 45 absorbs an axial force that is directed parallel to the longitudinal axis 32 . Also, the second thrust bearing 45 receives a radial load. This radial force is based on the first axial bearing 33, which is absorbed by the swash plate 18 at an angle to the longitudinal axis 32. The axial force is significantly higher than a radial force, which is also absorbed by the second axial bearing 45.

The balls 38 of the first and second axial bearing 33, 45 are each guided on a pitch circle in a respective raceway 39. Provision is advantageously made for the pitch circle of the first axial bearing 33 to be the same size as or larger than the pitch circle on which the pistons 22 of the piston pump 21 are arranged. Furthermore, it is preferably provided that the pitch circle of the second axial bearing 45 is the same size as or larger than the pitch circle of the first axial bearing 33 . The first and second thrust bearing 33, 45 can be structurally identical and preferably differ in diameter or installation dimensions. Alternatively, the first and second axial bearings 33, 45 can also differ from one another in terms of their structural design.

In Figure 3 is a first embodiment of the thrust bearing 33, 45 in a

Top view shown. Figure 4 shows a sectional view along the line III-III in Figure 3. Figure 5 shows a schematic sectional view of the thrust washer 37. Figure 6 shows a schematic view of a cage 41 with balls 38.

FIG. 7 shows a schematic sectional view along the line VI-VI in FIG.

The axial bearing 33 has a first and a second thrust washer 37 which, viewed in cross section, are configured as mirror images of one another. A contact surface 42 is provided on each outer side of the thrust washer 37 . This contact surface 42 is delimited by an internal opening 43 . A raceway 39 is provided on an inner surface 47 of the thrust washer 37, through which the balls 38 are guided in a circumferential manner. The track 39 can be introduced into the surface of the thrust washer 37 with a depth of less than 2.5 mm. In particular, the depth of the track 39 can be in a range from 0.6 mm to 2.3 mm. The raceway 39 preferably has an average roughness value Ra of 1 or less, in particular an Ra value equal to or less than 0.5.

The axial bearing 33 is designed differently from a DIN standard. This axial bearing 33 is a special solution. This axial bearing 33 has an osculation in a range equal to or less than 0.53. Osculation is the ratio of a radius R of the raceway 39 to a diameter D of the ball 38, ie S=R/D. The osculation S is advantageously less than 0.525. For example, the ball 38 can have a diameter D of 6 mm to 6.5 mm, in particular 6.35 mm, or a diameter D in a range of 7.2 to 7.8 mm, in particular 7.5 mm. The radius R of the track 39 is in a range from 3.0 to 4.0 mm, in particular in a range between 3.2 and 3.9 mm. The track 39 is introduced into the inner surface 47 with a depth of 0.5 mm to 1.2 mm. The osculation (S=R/D) with a radius R of the raceway 39 of, for example, R=3.2 mm and with a diameter D of the ball 38 of, for example, D=6.35 mm is S=0.504.

For example, an axial bearing 33, in particular an axial grooved ball bearing, can have balls 38 with a diameter of 6.35 mm, which move in a raceway 39 with a radius of 3.3 mm on a pitch circle diameter of 44 mm and a depth of the raceway of 0. 8 mm are guided. An outer diameter of the thrust washers 37 is at least 50 mm. If, for example, a lower load transfer is required with the same installation dimensions, the balls 38 can have a diameter of 7.5 mm, which are guided in a raceway 39 with a radius of 3.8 mm on a pitch circle diameter of 42 mm on the thrust washer 37. the track 39 being formed with a recess of 1.15 mm.

In the case of the axial bearings 33 described above by way of example, an osculation S in a range between 0.50 and 0.525, in particular in a range between 0.51 and 0.52, is advantageously provided. As a result, the guidance of the balls 38 can be improved and the load-bearing capacity and thus the service life can be increased. The thrust washers 37 are preferably made of a high-alloy steel, in particular chromium steel, such as 100 Cr6. The track 39 of the thrust washer 37 can be polished, for example.

The cage 41 for receiving the balls 38 according to FIGS. 6 and 7 is made of plastic, for example. A polyamide or other temperature-resistant, thermoplastic materials can be used for this. The cage 41 has a stiffening contour 51 lying radially on the inside, for example segment-shaped openings 52 with webs 53 in between. An inner opening 54 of the stiffening contour 51 corresponds to the inside diameter of the opening 43 or is larger. Advantageously, two webs 53 are aligned in a range of, for example, 60° to one another and enclose the segment-shaped opening 52 in between. For example, 30° or 45° angles can also be selected.

FIG. 8 shows a schematic sectional view of an alternative embodiment of the first axial bearing 33 according to FIGS. 3 to 7. This The embodiment according to FIG. 8 is preferably intended to be arranged between the swash plate 18 and the piston pump 21 . The contact surface 42 of one thrust washer 37 is wider than the contact surface 42 of the other thrust washer 37 . The outside diameter of both thrust washers 37 is the same, while the diameter of the inner opening 43 is different. This first axial bearing 33 is preferably installed with the wider contact surface 42 of the thrust washer 37 pointing towards the piston 22 .

As a result, the possible contact area of the pistons 22 is increased. Piston pumps 21 of different sizes can be used, i.e. the pitch circle of the pistons 22 of the piston pumps 21 can vary.

An alternative embodiment of the axial bearing 33, 45 is shown in FIG. The configuration of the axial bearing according to FIG. 9 is preferably used as the second axial bearing 45 . For example, balls 38 with a diameter of 6.35 mm with an outer diameter of 45 mm and an inner diameter of the opening 43 of 45 mm, for example, are used in this axial bearing 45 . Advantageously, the osculation can be 0.52. The cage 41 is designed, for example, as a U-shaped ring with openings for receiving the balls 38, the balls 38 being held captive in relation to the cage 41 by this geometric configuration. The cage 41 is formed and made in particular from a plastic material such as polyamide.

Claims

P A T E N T L A N G A N G E S Motor pump unit (11), in particular for a high-pressure cleaning device,

- with a motor (12),

- with a gear (16) which is driven by the motor (12) and drives an output shaft (17) of the gear (16) which rotates about a longitudinal axis (32),

- with a swash plate (18) arranged non-rotatably on the output shaft (17),

- With a piston pump (21) assigned to the swash plate (18) and comprising a plurality of pistons (22) that can be actuated, and

- having a first axial bearing (33) arranged between the swash plate (18) and the piston pump (21), characterized in that

- that the swash plate (18) is mounted in a connection housing (44), through which the motor (12) and the piston pump (21) can be connected, by a second axial bearing (45) rotating to the connection housing (44). Motor pump unit (11) according to Claim 1, characterized in that the first and/or second axial bearing (33, 45) is designed as an axial grooved ball bearing. Motor-pump unit (11) according to Claim 1 or 2, characterized in that the swash plate (18) comprises a first connection point (36) pointing towards the piston pump (21) and having a support surface (34) for the first axial bearing (33) which is inclined with respect to the longitudinal axis (32) of the output shaft (17), and opposite it comprises a second connection point (46) for the second axial bearing (45), pointing towards the transmission (16), which has a support surface (34) which is radial to the Longitudinal axis (32) of the output shaft (17) is aligned. Motor pump unit (11) according to Claim 3, characterized in that the first and second connection points (36, 46) each comprise an annular collar (35) which is formed radially on the inside of the support surface (34). Motor-pump unit (11) according to one of the preceding claims, characterized in that the axial bearing (33, 36) comprises two opposing thrust washers (37), each with an inner raceway (39) for balls (38), in particular a flat contact surface on the outside (42) and/or preferably the balls (38) are guided through a cage (41). Motor pump unit (11) according to one of the preceding claims, characterized in that the balls (38) of the first axial bearing (33) are guided on a pitch circle which is the same size as or is radially outside a pitch circle of the piston pump (21) on which the pistons (22) are arranged. Motor pump unit (11) according to one of the preceding claims, characterized in that a pitch circle of the balls (38) of the second thrust bearing (45) is equal to or larger than the pitch circle of the balls (38) of the first thrust bearing (33). Motor pump unit (11) according to one of the preceding claims, characterized in that the outer contact surface (42) of the thrust washers (37) of the axial bearings (33, 45) are of the same size. Motor pump unit (11) according to one of Claims 1 to 7, characterized in that the outer contact surface (42) of one thrust washer (37) is larger than the outer contact surface of the opposite thrust washer (37) of the first axial bearing (33), and that the Pressure disc (37) with the larger contact surface (42) is arranged pointing to the piston pump (21) on the swash plate (18). Motor pump unit (11) according to one of the preceding claims, characterized in that each thrust washer (37) of the axial bearing (33, 45) has an osculation which at a ratio of a radius of the raceway (39) to a diameter of the ball (38) is less than 0.53, preferably less than 0.52. Motor pump unit (11) according to one of Claims 1 to 9, characterized in that each thrust washer (37) of the axial bearing (33, 45) has an osculation which, at a ratio of a radius of the raceway (39) to a diameter of the ball ( 38) is in a range between 0.49 to 0.53, preferably between 0.50 and 0.525, more preferably between 0.51 to 0.52. Motor pump unit (11) according to one of the preceding claims, characterized in that a depth of the raceway (39) for the balls (38) in the thrust washer (37) is less than 2.5 mm, in particular in a range between 0.5 and 1 .2mm. Motor pump unit (11) according to any one of the preceding claims, characterized in that the balls (38) have a diameter of 6.0 to 6.5 mm, in particular 6.35 mm or a diameter of 7.2 to 7.8 mm, in particular 7.5 mm, and the thrust washers (37) preferably have an outer circumference of at least 50 mm. Motor pump unit (11) according to one of the preceding claims, characterized in that the axial bearings (33, 45) for an axial load in a range from 2,500 to 3,500 N (Newton) and a radial load in a range from 250 to 600 N, in particular for a speed range from 3,000 to 7,000 rpm (revolutions per minute). Motor-pump unit (11) according to Claim 2, characterized in that the axial grooved bearing comprises a cage (41) made of plastic, and is preferably made of polyamide.