Swash drive

Abstract

The invention relates to a swash drive (10) for a high-pressure cleaning unit, with a motor shaft (20) which is mounted rotatably about a rotational axis (18), and with a swash unit (22), comprising a swash element (32; 108; 118) and a swash plate (34), between which a swash plate bearing (44) is arranged, wherein the swash element (32; 108; 118) has a first, spherically curved bearing surface (56; 110) and a second bearing surface (60; 112). The swash element (32; 108; 118) can be connected to the motor shaft fixedly for conjoint rotation by means of a screw connection device (30) which can be placed flatly onto the first bearing surface (56; 110). The second bearing surface (60; 112) can be placed onto a holding surface (71) which is assigned to the motor shaft (20). In order to develop the swash drive (10) in such a way that simple mounting and manufacture are made possible, it is proposed that the swash element (32; 108; 118) is configured as a single-part solid component, wherein the second bearing surface (60; 112) is arranged in a planar manner perpendicularly with respect to the rotational axis (18), and the swash plate bearing (44) is supported on a supporting plate (50).

Description

[0001] WOMB DRIVE

[0002] The invention relates to a wobble drive for a high-pressure cleaning device, comprising a motor with a motor shaft mounted for rotation about a rotational axis and a wobble unit with a wobble body that can be driven for rotation about the rotational axis and a wobble plate, the end face of which is remote from the wobble body and is inclined to the rotational axis, wherein a wobble plate bearing is arranged between the wobble body and the wobble plate, wherein the wobble body has a first, spherically curved contact surface on a front side facing the wobble plate and a second contact surface on a rear side facing the motor shaft, wherein a central opening extends from the first contact surface to the second contact surface, and wherein the wobble body can be connected in a rotationally fixed manner to the motor shaft by means of a screw connection device, wherein the screw connection device comprises a connecting screw that penetrates the central opening,whose longitudinal axis is aligned coaxially with the axis of rotation, wherein the screw connection device can be placed flat against the first contact surface, and wherein the second contact surface can be placed against a flat holding surface which is aligned perpendicular to the axis of rotation and which is arranged directly on the motor shaft or on a component connected to the motor shaft in a rotationally fixed manner.

[0003] DE 42 05 859 A1 discloses a wobble drive comprising a motor with a motor shaft mounted for rotation about a rotational axis, and a wobble unit. The wobble unit comprises a wobble plate and a wobble body formed from sheet metal. The wobble plate is supported on a support surface of the wobble body via a wobble plate bearing. Such wobble drives are used in axial piston pumps to convert the rotary motion of the motor shaft into a reciprocating motion of pistons resting against an end face of the wobble plate. The pistons can then periodically suck in liquid, preferably water, pressurized, and discharged via a pressure line. If the delivery rate of the axial piston pump is to be changed, the stroke of the pistons can be changed by changing the inclination of the wobble plate. The greater the inclination of the wobble plate to the rotational axis, the greater the piston stroke.

[0004] If the piston stroke needs to be changed, this can be done by tilting the wobbler, which has a spherically curved contact surface on its rear side facing the motor shaft. This allows the piston stroke to be adjusted and makes it possible to use a single wobbler design for various axial piston pumps with different flow rates. The inclination of the wobbler must be adjusted during assembly and subsequently checked, which makes installation complex.

[0005] The design of the wobbler as a sheet metal component requires a forming process and subsequent processing during production, for example, in the form of heat treatment. Heat treatment hardens the support surface on which the swash plate bearing rests. This is necessary to achieve the wear resistance of the wobbler. Manufacturing the wobbler drive requires several production steps, which makes it complex.

[0006] The object of the present invention is to provide a wobble drive of the type mentioned above which is simple to assemble and manufacture.

[0007] This object is achieved according to the invention in a wobble drive of the generic type in that the wobble body is designed as a one-piece solid component, wherein the second contact surface is flat and oriented perpendicular to the axis of rotation, and in that the swash plate bearing is supported on a support plate that can be connected to the wobble body and that rests against a support surface of the wobble body that is aligned parallel to the end face of the swash plate. In the wobble drive according to the invention, the wobble body is designed as a one-piece solid component. Due to the one-piece nature of the wobble body, production can take place in a single step. Likewise, assembling various components to form a wobble body is not necessary. This allows manufacturing steps to be reduced.

[0008] The swashplate bearing is supported on a support plate, which rests on a support surface of the swash body aligned parallel to the front of the swashplate. The surface against which the swashplate bearing is supported is subject to high mechanical loads and, according to the invention, is formed by the support plate. Mechanical wear on the surface against which the swashplate bearing is supported can be counteracted, for example, by choosing a hard material for the support plate or by means of heat treatment to harden the surface of the support plate. By supporting the swashplate bearing on the support plate, rather than directly on the support surface of the swash body, post-processing of the swash body, for example by means of heat treatment to harden the support surface, is not necessary. This reduces the manufacturing effort for the swash body.

[0009] The second contact surface of the swash plate is flat and arranged perpendicular to the axis of rotation. The support surface of the swash plate is aligned parallel to the end face of the swash plate, creating an angle of inclination between the support surface and the second contact surface that determines the piston stroke of reciprocating pistons arranged parallel to the axis of rotation and resting against the end face of the swash plate. The second contact surface can be placed on the motor shaft side against the flat and perpendicular holding surface of the motor shaft or a component connected to the motor shaft in a rotationally fixed manner. The flat and perpendicular second contact surface and the flat and perpendicular holding surface enable very simple assembly of the swash plate, the geometry of which determines the piston stroke.This means that the angle of inclination does not need to be adjusted and checked during installation.

[0010] The wobble body has a front and a back. The spherically curved first contact surface is arranged on the front of the wobble body, and the flat second contact surface, oriented perpendicular to the motor shaft, is arranged on the back and can be placed against the flat holding surface oriented perpendicular to the motor shaft. The screw connection device, with which the wobble body is connected in a rotationally fixed manner to the motor shaft, can be placed flat against the first contact surface. The spherically curved first contact surface allows the screw connection device to rest flatly on the first contact surface regardless of the angle of inclination, and thus an even distribution of force from the screw connection device via the first contact surface and the second contact surface to the holding surface and thus to the motor shaft. The center of the sphere forming the first contact surface is defined by a point of intersection of the axis of rotation with the front side of the swash plate.This ensures centering of the swashplate relative to the rotation axis, independent of the tilt angle. The flat second contact surface allows for a simple geometric design of the rear side of the swashplate.

[0011] Preferably, the spherically curved first contact surface is concave.

[0012] Depending on the desired piston stroke, the wobble drive according to the invention uses a wobble body with an angle of inclination between the support surface and the second contact surface corresponding to the piston stroke. Different wobble bodies are thus characterized solely by different angles of inclination, although the front of the wobble body can be designed consistently for all angles of inclination, and only the angle of inclination of the flat second contact surface relative to the support surface needs to be changed. The production of wobble bodies with different angles of inclination is thus very simple. To make the production of the wobble body particularly simple, the wobble body is preferably manufactured using a tool that comprises at least one molded part.

[0013] Advantageously, the tool comprises a first mold part and a second mold part. The front side of the wobble body can be formed using the first mold part, and the rear side of the wobble body can be formed using the second mold part. Due to the spherically curved first contact surface, for wobble bodies with different angles of inclination, only an adjustment of the geometrically simple rear side and thus of the second mold part is necessary. Thus, the first mold part forming the front side of the wobble body can remain the same for all desired angles of inclination. This enables simple production of wobble bodies with different angles of inclination and simple assembly.

[0014] The wobble body is preferably a cast part. This allows for particularly simple and cost-effective production.

[0015] The wobble body is particularly preferably an aluminum die-cast part. The aluminum die-casting process allows for the production of particularly dimensionally accurate components with good surface quality, eliminating the need for post-processing.

[0016] It is advantageous if the swash plate bearing is designed as a rolling bearing.

[0017] Preferably, the wobble body has at least one centering element for centering the support disc relative to the wobble body. This facilitates the precise positioning of the support disc on the wobble body.

[0018] It is advantageous if the at least one centering element forms a positive-locking element, whereby the support disc can be connected to the wobble body in a rotationally fixed manner by means of the positive-locking element. The support disc can be connected to the wobble body, for example, by pressing it on.

[0019] In an advantageous embodiment of the invention, the screw connection device is designed as a single piece in the form of a connecting screw, which has a screw head that rests flat against the first contact surface. The screw head is shaped to correspond to the first, spherically curved contact surface, thus enabling a uniform distribution of force from the connection device via the first contact surface and the second contact surface to the retaining surface and thus to the motor shaft.

[0020] Alternatively, the screw connection device can be designed in two parts and comprise a connecting screw and a washer, with the washer resting flat against the first contact surface. This allows the use of a standard screw as the connecting screw. In combination with a washer surface that is spherically curved corresponding to the first contact surface and facing the first contact surface, a uniform force distribution from the connecting device via the first contact surface and the second contact surface to the retaining surface and thus to the motor shaft can be achieved.

[0021] In addition to the screw connection, the wobble body can be advantageously connected to the motor shaft by means of a positive connection. This provides anti-twist protection between the wobble body and the motor shaft.

[0022] The following description of preferred embodiments of the invention serves to explain it in more detail in conjunction with the drawings. They show:

[0023] Figure 1: a sectional view of a high-pressure cleaning device with a first embodiment of a wobble drive; Figure 2: an enlarged view of detail X from Figure 1;

[0024] Figure 3: a perspective view of a wobble unit of the wobble drive from Figure 1, obliquely from behind;

[0025] Figure 4: a sectional view of the wobble unit along the line 4-4 of

[0026] Figure 3;

[0027] Figure 5: a perspective view of a wobble body of the wobble drive from Figure 1, obliquely from the front;

[0028] Figure 6: a sectional view corresponding to Figure 4 of a second embodiment of a wobble drive;

[0029] Figure 7: a sectional view corresponding to Figure 4 of a third embodiment of a wobble drive;

[0030] Figure 8: an enlarged view corresponding to Figure 2 of a fourth embodiment of a wobble drive;

[0031] Figure 9: a perspective view of a wobble unit of the wobble drive from Figure 8, obliquely from behind;

[0032] Figure 10: a sectional view of the wobble unit taken along line 10-10 of Figure 9;

[0033] Figures 1 to 5 schematically show a first embodiment of a wobble drive according to the invention for a high-pressure cleaning device, which is designated overall by the reference numeral 10.

[0034] The high-pressure cleaning device comprises an axial piston pump 12 with pistons 14, which are driven by the wobble drive 10. The wobble drive 10 comprises a motor 16 with a motor shaft 20 mounted for rotation about a rotation axis 18, and a wobble unit 22. The motor shaft 20 is rotatably mounted by means of a ball bearing 24, which has an inner ring 26 connected in a rotationally fixed manner to the motor shaft and an outer ring 29 connected in a rotationally fixed manner to a housing 28.

[0035] The wobble unit 22 comprises a wobble body 32 connected to the motor shaft 20 by means of a screw connection device 30 and a flat, annular wobble plate 34, on the end face 36 of which facing away from the wobble body 32 the pistons 14 of the axial piston pump 12 rest resiliently by means of piston springs 38.

[0036] The screw connection device 30 is designed as a connecting screw 40. The longitudinal axis 42 of the connecting screw 40 is aligned coaxially with the rotational axis 18. A swash plate bearing 44 is arranged between the swash plate 34 and the swash body 32. The swash plate bearing 44 comprises spherical rolling elements 46 and a bearing cage 48 that surrounds the rolling elements 46. The swash plate bearing 44 is supported on a support plate 50 connected to the swash body 32. The support plate 50 is annular and rests flat against a support surface 51 of the swash body 32, which is aligned parallel to the end face 36 of the swash plate 34.

[0037] The wobble body 32 comprises a front section 52 extending from the support surface 51 in the direction of the swash plate 34 and a rear section 53 extending from the support surface 51 in the direction of the motor shaft 20. The support surface 51 divides the wobble body 32 into the front section 52 and the rear section 53.

[0038] The wobble body 32 has a first, spherically inwardly curved contact surface 56 on a front side 54 facing the swash plate 34 and arranged on the front section 52, and a second contact surface 60 that is flat and oriented perpendicular to the axis of rotation 18 on a rear side 58 facing the motor shaft 20 and arranged on the rear section 53. A central opening 62 extends from the first contact surface 56 to the second contact surface 60. The connecting screw 40 comprises a screw head 64 and a screw shaft 66. The screw shaft 66 passes through the central opening 62 and is screwed into a central threaded bore 68 arranged on an end face 70 of the motor shaft 20, which is aligned coaxially to the axis of rotation 18. The screw head 64 is designed to be complementary to the first contact surface 56 and rests flat against the first contact surface 56.The second contact surface 60 rests against a flat support surface 71 oriented perpendicular to the rotational axis 18, which is formed by an end face 72 of the inner ring 26 of the radial deep groove ball bearing 24 facing the wobble body 32. The support surface 51 of the wobble body 32, arranged parallel to the end face 36 of the wobble plate 34, forms an angle of inclination α relative to the second contact surface 60.

[0039] As is clear from Figure 5, the wobble body 32 has 54 centering elements 73 on its front side, which in turn form positive-locking elements 74 and extend parallel to the rotational axis 18 in the direction of the wobble plate 34. An inner edge 76 of the annular support plate 50 rests against the outer surfaces 75 of the positive-locking elements 74.

[0040] At the front section 52, the wobble body 32 has a first mounting element 78 and a second mounting element 80 arranged circumferentially offset from the first mounting element 78. The mounting elements 78, 80 each comprise a wing 82, 84 and a flank 86, 88. The wings 82, 84 extend perpendicular to the support surface 51 in the direction of the swash plate 34. The flanks 86, 88 extend radially outward from the support surface 51.

[0041] The wobble drive 10 can be mounted as follows:

[0042] First, the support disk 50 is pressed onto the swash plate 32 so that the outer surfaces 75 of the form-locking elements 74 rest against the inner edge 76 of the support disk 50 and the support disk 50 rests against the support surface 52 of the swash plate 32. The swash plate bearing 44 is then placed onto the support disk 50. Following this, the swash plate 34 is positioned on the swash plate bearing 44. To prevent the swash plate unit 22 from falling apart during the assembly process, the swash plate bearing 44 and the swash plate 34 can rest against the wings 82, 84 of the mounting elements 78, 80. In a further assembly step, the outer surfaces 90, 92 of the flanks 86, 88, which are aligned parallel to one another, can be grasped using an assembly tool. The wobble unit 22 can now be brought into position and screwed to the motor shaft 16 using the connecting screw 40.Due to the flat contact of the screw head 64 on the first contact surface 56, the wobble body 32 is clamped with its second contact surface 60 against the holding surface 71 and thus connected to the motor shaft 20 in a rotationally fixed manner.

[0043] Figure 6 schematically shows a wobble unit of a second embodiment of a wobble drive according to the invention. The wobble unit of the second embodiment is identical to the wobble unit 22 of the first embodiment. In the second embodiment, the screw connection device 30 is designed in two parts and comprises a connecting screw 94 and a washer 96. The connecting screw 94 comprises a screw head 98 and a screw shaft 100. The washer 96 is arranged between the screw head 98 and the wobble body 32 and, like the central opening 62 of the wobble body 32, is penetrated by the screw shaft 100. A longitudinal axis 102 of the connecting screw 94 is arranged coaxially to the axis of rotation 18. The washer 96 is flat on a front side 104 facing the screw head and spherically curved on its rear side 106 facing away from the screw head 98.

[0044] Figure 7 schematically shows a wobble unit of a third embodiment of a wobble drive according to the invention. The third embodiment differs from the first and second embodiments in the geometry of the wobble body.

[0045] The third embodiment of the wobble drive uses a wobble body 108 corresponding to the wobble body 32 of the first embodiment. The wobble body 108 has a first contact surface 110, which is spherically curved, a second contact surface 112, which is flat and arranged perpendicular to the rotational axis 18, and a support surface 113, which is aligned parallel to the end face of the swash plate 34. The first contact surface 110 is arranged on a front section 114 of the wobble body 108, which extends from the support surface 113 in the direction of the swash plate 34. The second contact surface 112 is arranged on a rear section 115 of the wobble body 108, which extends from the support surface 113 in the direction of the motor shaft 20. The front section 114 and the rear section 115 are separated by the support surface 113.

[0046] The screw head 64 of the connecting screw 40 can be placed flat against the first contact surface 110. The second contact surface 112 rests against the holding surface 71. The support plate 50 rests flat against the support surface 113 of the wobble body 108. The wobble plate 34 is supported on the support plate 50 via the wobble plate bearing 44. The support surface 113 and the second contact surface 112 assume an inclination angle β to one another. The inclination angle β of the third embodiment is smaller than the inclination angle α of the first and second embodiments.

[0047] The front section 114 of the third embodiment of the wobble drive is identical to the front section 52 of the first and second embodiments, the rear section 115 differs from the rear section 53 of the first and second embodiments only by the different angle of inclination ß.

[0048] Figures 8 to 10 schematically illustrate a fourth embodiment of a wobble drive according to the invention. The fourth embodiment essentially corresponds to the first and second embodiments with regard to the wobble body shape. In the fourth embodiment, a wobble body 118 is used, which has a recess 120 on its rear side 58 facing the motor shaft 20. The recess 120 has a flat first side surface 122 and a flat second side surface 124 opposite the first side surface 122, which are connected to one another via a circular third side surface 126 and a circular fourth side surface 128. A motor shaft end section 130 shaped to correspond to the recess 120 can be inserted into the recess 120. This serves to prevent rotation between the wobble body 118 and the motor shaft 20.

Claims

PATENT CLAIMS Wobble drive for a high-pressure cleaning device, comprising a motor (16) with a motor shaft (20) rotatably mounted about an axis of rotation (18) and a wobble unit (22) with a wobble body (32; 108; 118) rotatably driven about the axis of rotation (18) and a swashplate (34), the end face (36) of which facing away from the wobble body (32; 108; 118) is inclined to the axis of rotation (18), wherein a swashplate bearing (44) is arranged between the wobble body (32; 108; 118) and the swashplate (34), wherein the wobble body (32; 108; 118) has a first spherically curved contact surface (56; 110) on a front face (54) facing the swashplate (34) and a rear face (58) facing the motor shaft second mounting surface (60; 112), wherein a central opening (62) extends from the first mounting surface (56; 110) to the second mounting surface (60; 112), and wherein the wobble body (32; 108;118) is rotatably connected to the motor shaft (20) by means of a screw connection device (30), wherein the screw connection device (30) comprises a connecting screw (40; 94) extending through the central opening (62), the longitudinal axis (42; 102) of which is aligned coaxially to the axis of rotation (18), wherein the screw connection device (30) can be applied flatly to the first contact surface (56; 110), and wherein the second contact surface (60; 112) can be applied to a flat retaining surface (71) oriented perpendicular to the axis of rotation (18), which is arranged directly on the motor shaft (20) or on a component non-rotatably connected to the motor shaft, characterized in that the wobble body (32; 108; 118) is designed as a one-piece solid component, wherein the second contact surface (60; 112) is flat and oriented perpendicular to the axis of rotation (18) is aligned, and that the swashplate bearing (44) is aligned with the swashplate body (32; 108;118) connectable support disc (50) which is supported on a parallel to the front face (36) of the wobble-; The support surface (51; 113) of the wobble body (32; 108; 118) rests against the disk (34). Wobble drive according to claim 1, characterized in that the wobble body (32; 108; 118) is a cast part. Wobble drive according to any of the preceding claims, characterized in that the wobble disk bearing (44) is designed as a rolling bearing. Wobble drive according to any of the preceding claims, characterized in that the wobble body (32; 108; 118) has at least one centering element (73) for centering the support disk (50) relative to the wobble body (32; 108; 118). Wobble drive according to claim 4, characterized in that the at least one centering element (73) forms a positive locking element (74), wherein the support disk (50) can be connected to the wobble body (32; 108; 118) in a rotationally fixed manner by means of the positive locking element (74).A wobble drive according to any one of the preceding claims, characterized in that the screw connection device (30) is designed in one piece in the form of a connecting screw (40) which has a screw head (64) that bears flat against the first contact surface (56; 110). A wobble drive according to any one of claims 1 to 5, characterized in that the screw connection device (30) is designed in two parts and comprises a connecting screw (94) and a washer (96), wherein the washer (86) bears flat against the first contact surface (56; 110).

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