DE29607300U1 - Ball piston pump - Google Patents

Description

Ball piston pump

The invention relates to a ball piston pump for pumping a wide variety of media in a wide range of applications.

Ball piston pumps work on the displacement principle similar to reciprocating piston pumps, but with an improved flow characteristic that corresponds to an ideal sinusoidal shape. They also do not require any valves to reverse the flow direction.

Although ball piston pumps have been known for a long time, their use has so far been limited to special applications. The reason for this was the complex, precise manufacturing required to reduce friction and sealing problems to an acceptable level. Manufacturing the numerous spherical surfaces with tight tolerances posed particular problems.

Due to the obvious pressure-related advantages of the ball design, the ball piston pump has repeatedly been the subject of inventions, without any significant improvement in quality being achieved compared to other types of pumps, such as centrifugal, reciprocating or circulating piston pumps.

DE PS 808 915 describes a four-chamber ball piston pump, which works similarly to a universal joint. It consists of a spherical hollow body into which a drive shaft and a blind shaft arranged at an angle to it protrude. Both shafts are provided with slides arranged orthogonally to each other, which cause a ball piston to rotate. The slides slide into recesses in the ball piston, so that four chambers are created, which are enlarged and reduced in size one after the other during one revolution and thus pump the medium from an inlet channel into an outlet channel.

In order for the pump to be designed for high pressures, the sealing surfaces between the slides and the recesses in the ball piston must be very wide, which leads to a reduction in the effective chamber volume.

A further disadvantage of such pumps is that the friction surfaces between the piston recesses and the sliders serve to transmit power, which further increases friction and causes a large heat effect.

Another design of the ball piston pump is described in DE PS 1 010 834. A ball body is attached to a continuous drive shaft, in which pistons are guided in grooves along the meridians of the ball body, which are arranged in an articulated manner on a guide ring, the axis of which is inclined at an angle to the drive shaft. The pistons are moved back and forth in the grooves of the ball body by a rotary movement of the drive shaft.

This design combines the advantages of the ball piston pump with those of a reciprocating piston pump. The disadvantage is that the increase in pump performance is achieved by increasing the space required for the entire pump arrangement. The effective working space of the chambers could not be significantly increased, and additional counterforces must be applied to guide the radially engaging pistons in order to compensate for the radial forces. The fact that the pistons are guided from the outside into the working spaces of the spherical body increases the friction and sealing problems.

In DE OS 15 53 165, the ball piston pump, which can also be operated as a ball motor, was simplified and improved by reducing the ball piston to a wobble plate. A universal joint rotary piston rotates in a spherical housing, which consists of a circular disk that is articulated between two semicircular disks that are aligned orthogonally to one another. The circular disk and the two semicircular disks are designed to be so large in radius that they completely fill the spherical housing and thus divide it into four chambers. Each of the two semicircular disks is connected radially in its center to an axle socket.

·· t it &igr;.

one of which serves as the drive axle and the other is blind.

If the axes of rotation of the two semicircular disks thus formed are inclined at an angle to each other, a tumbling movement of the circular disk occurs when the axes rotate and the four chambers are successively enlarged and reduced in size during one rotation.

The disadvantage of this ball pump (or ball motor) is the high load and the associated wear in the joints between the swash plate and the driving semicircular disks. Since the joints also serve to transmit power, frictional forces and torques overlap.

In the practical applications of ball piston pumps with swash plates, the joints consist of sliding surfaces, whereby the semicircular discs are rounded at the edge along their diameter in a cylindrical shape and engage in corresponding curved grooves on the swash plate. Since these joints are subject to very high wear, especially at high speeds and/or high pressures, the application of these pumps is limited.

In order to increase the service life of such pumps, it is therefore proposed, e.g. according to DE OS 43 40 692, to coat the friction surfaces on these joints or all rubbing parts of the ball piston pump with a wear-resistant ceramic. This technology is very complex and results in a high price, which prevents the widespread use of these ball piston pumps.

In addition, in the known ball piston pumps with wobble plates, the cylindrical sliding surfaces must be very wide if they are to withstand high pressures and ensure adequate sealing, which reduces the effective working space of the pump and impairs its efficiency.

It is therefore the object of the invention to create a ball piston pump which is simple and wear-resistant in construction, has a high level of efficiency and allows a universal application area for a wide variety of pressures and media.

The object is achieved according to the invention with the features of the first protection claim. Advantageous further developments and embodiments are the subject of the subclaims.

According to the basic idea of the invention, a wing-like piston rotates in a spherical working space and at the same time performs a back and forth movement. The conversion of the rotary movement of a drive shaft into a rotating and oscillating movement of the piston takes place through rotating and interlocking working elements within the spherical working space.

The ball piston pump is very compact and pressure-resistant. Only one drive shaft and the necessary inlet and outlet channels lead into the spherical working chamber.

The drive shaft is firmly connected to a relatively narrow drive disk, which divides the piston, referred to below as the rotary piston, lengthwise into two halves and can move in an oscillating manner within the rotary piston. The rotary piston has two axially symmetrical vanes and is rotatably mounted in a guide ring on its axis of rotation with the help of a sealing piston guide element. The guide ring is also rotatably mounted in a diameter of the spherical working chamber of the ball piston pump, but with a fixed axis of rotation. It divides the spherical working chamber into two equally sized hemispherical working chambers, so that one vane of the rotary piston extends into one working chamber and the other vane of the rotary piston extends into the other working chamber.

The rotary piston is rotated together with the guide ring via the drive shaft and the drive disk, with one wing of the rotary piston rotating in one working chamber and the other wing rotating in the other working chamber. The shape of the wings is designed in such a way that

*· t

They slide sealingly along the hemispherical interior of the chambers. The use of additional sealing agents, e.g. piston rings, is possible.

A swinging or wobbling effect of the rotary piston is generated when the drive shaft together with the rotation axis of the drive disk is inclined relative to the rotation axis of the guide ring by an angle α < 90°. Now the drive disk, which is positively guided by the drive shaft, swings in the rotary piston and the rotary piston swings with the help of the piston guide element in the guide ring, which in turn is positively guided within the spherical working space.

The movement of the rotary piston can be compared with the movement of the wobble plate of the ball piston pumps according to the state of the art. The difference, however, lies in the means by which this wobbling movement is generated. With the wobble plate, the power is transmitted through relatively narrow sliding joint surfaces, which, if one wants to transmit large pressures and forces, must be made relatively wide, which comes at the expense of the effective working volume.

In the solution according to the invention, a narrow oscillating drive disk, which can be equipped with relatively wide force transmission surfaces, is inserted into the piston. In this way, the working space is optimally utilized and the friction at this point can be reduced by suitable additional means, e.g. balls, and/or separate lubrication.

The rotating and oscillating movement of the rotary piston moves the medium to be pumped from an inlet channel (suction) to an outlet channel (exhaust). This process takes place synchronously in the two hemispherical working chambers, whereby each of the working chambers is provided with an inlet channel and an outlet channel and the working chambers are divided into two pumping chambers by a wing of the rotary piston. The inlet and outlet channels are therefore

into the working chamber in such a way that when the rotary piston moves, only one channel per delivery chamber is open at a time.

The following describes the functionality of the ball piston pump based on the position of the rotary piston or the angular position of the guide ring at 0°, 90° and 180°. Only one of the two analogously constructed hemispherical working chambers is considered:

0°: The inlet opening and the outlet opening are closed by the wing of the rotary piston. The 1st delivery chamber has a minimum delivery volume and the 2nd delivery chamber has a maximum delivery volume.

90°: The inlet opening is open and the medium flows into the enlarging 1st conveying chamber. The outlet opening is open and the medium flows out of the shrinking 2nd conveying chamber.

180°: Both openings are closed. The 1st delivery chamber has a maximum delivery volume and the 2nd delivery chamber has a minimum delivery volume. The position of the rotary piston is analogous to 0°, except that both delivery chambers are swapped.

Although the structure and operation of a pump has been described in the present invention, it will be obvious to a person skilled in the art to use the same arrangement as a motor.

The innovative design of the ball piston pump, its characteristic sinusoidal characteristic curve and its design-related properties mean that it can be used in a wide variety of ways. Its main area of application is the same as that of the reciprocating piston pump, but with considerably higher performance values.

Due to the pendulum, screw-shaped movement of the rotary piston, the ball piston pump is particularly suitable for pumping highly viscous liquids or liquids with solid components.

If two ball piston pumps according to the invention are operated in parallel, but with their delivery characteristics offset by 90°, a continuous delivery flow is obtained.

The ball piston pump can be continuously controlled via the speed. Another control option would be if the angle of the drive axis to the axis of rotation of the piston guide ring could be made variable.

The design-related two-chamber system with separate inlet and outlet channels allows two identical or different media to be conveyed synchronously or mixed.

The ball piston pump according to the invention has a wide range of applications. It can be used in laboratory and medical technology, e.g. as a micro pump or metering pump, as a feed pump for oils and petrol, as a water pump with a high delivery capacity, such as bilge pumps, domestic water systems or water jet drives for boats. Other applications are possible for compressors and condensers or as a vacuum pump. The ball piston pump can also be used in control and regulation technology as a hydraulic or pneumatic component.

An embodiment of the inventive solution is described in more detail using drawings. They show:

Fig. 1 A partially sectioned perspective view of the ball piston pump.

Fig. 2 A section A-A through the ball piston pump according to Fig. 1 with the guide ring for the rotary piston in the 0° position.

Fig. 3a A section A-A through the ball piston pump according to Fig. 1 with the guide ring for the rotary piston in the 90" position.

Fig. 3b A section B-B through the ball piston pump according to Fig. 3a.

Fig. 4 A section A-A through the ball piston pump according to Fig. 1 with the guide ring for the rotary piston in the 180" position.

Fig. 5 A representation of the guide ring in top and side views.

Fig. 6 A representation of the rotary piston in plan and side elevation.

Fig. 7 A representation of the rotary piston guide element.

Fig. 8 A representation of the drive pulley in two possible embodiments.

The ball piston pump according to the invention is shown in perspective in Fig. 1 in section. It consists of a housing 1 which surrounds a spherical working space 2 for accommodating all the elements required for the pumping process. For better assembly, the spherical housing 1 consists of two half shells 1a and 1b which are connected to one another by suitable means, e.g. a screwed flange connection 7. Openings lead into the housing 1, one of which (not visible in Fig. 1) serves to accommodate a drive shaft 8 and four others which are required as inlet channels 11a and 11b and as outlet channels 12a and 12b. The arrangement of the inlet and outlet channels 11a, 11b, 12a, 12b shown in Fig. 1 applies to anti-clockwise rotation of the drive shaft 8. When the direction of rotation is reversed (clockwise rotation), 12a and 12b are the inlet channels and 11a and 11b are the outlet channels. The outlet channel 12b is hidden in the illustration in Fig. 1 and therefore cannot be seen. .

The spherical working space 2 is divided into two hemispherical working chambers 2a and 2b by a rotatably arranged guide ring 3, whereby the axis of rotation 9 is perpendicular to the plane of the guide ring 3 and is arranged in a fixed position within the housing 1 of the ball piston pump. With the help of a suitable bearing 17, the guide ring 3 is in

the spherical housing 1, conveniently embedded at the location of the flange connection 7.

Each of the hemispherical working chambers 2a and 2b formed by the arrangement of the guide ring 3 has an inlet channel 11a and 11b and an outlet channel 12a and 12b for the medium to be conveyed.

Within the guide ring 3, a rotary piston 4, consisting of two wings 4a and 4b and a piston guide element 13, is arranged so as to be rotatable about an axis 14 that the plane of the rotary piston 4 intersects the plane of the guide ring 3 in its center in such a way that one wing 4a of the rotary piston 4 projects into the first hemispherical working chamber 2a and the other wing 4b of the rotary piston 4 projects into the second hemispherical working chamber 2b. The angle between the plane of the guide ring 3 and the plane of the rotary piston 4 can be changed via the axis 14.

The rotary piston 4 has a milled recess or a slot 5 in a plane running through its wings 4a, 4b, into which a drive disk 6 is inserted, which is arranged to rotate both within the slot 5 about an axis 15 perpendicular to the plane of the rotary piston 4 or the drive disk 6 and about a fixed axis 10 through the plane of the drive disk 6 around the drive shaft 8. To achieve a pendulum effect of the rotary piston 4, the fixed axis 10 of the drive disk 6 is inclined to the axis of rotation 9 of the guide ring 3 by a fixed angle α < 90°, preferably 45°.

All axes 9, 10, 14, 15 meet at the center M of the spherical working space 2 of the ball piston pump, whereby the axes 9 and 10 are rotation axes and the axes 14 and 15 are pendulum axes.

The operation of the ball piston pump is explained using the drawings Fig. 2 to Fig. 4.

In Fig. 2, the ball piston pump according to Fig. 1 is shown in a section A-A, which lies in the plane of the rotation axis 9 of the guide ring 3.

The rotary piston 4 with its two vanes 4a and 4b can be seen in the housing 1, which is mounted in the guide ring 3 via the piston guide element 13. The drive disk 6, which is connected to the drive shaft 8, is inserted inside the rotary piston 4. The drive shaft 8 is fixed by a bore 16 in the housing 1 of the ball piston pump. The axis of rotation 10 of the drive shaft 8, which also runs through the plane of the drive disk 6, is inclined at an angle α = 45° relative to the axis of rotation 9 of the guide ring 3. The guide ring 3 divides the spherical working space 2 into two identical hemispherical working chambers 2a and 2b, in which the two vanes 4a and 4b of the rotary piston 4 move.

If the drive shaft 8 rotates around the axis 10, the rotary piston 4 with the guide ring 3 is rotated around the axis 9. Since the rotary piston 4 cannot avoid the drive axis 10, the drive disk 6 moves back and forth in the rotary piston 4 and, in addition to rotating around the axes 9 and 10, simultaneously performs a pendulum movement around the axis 14.

The guide ring 3 is mounted in the housing 1 by suitable means 17, for example ball or roller bearings. To facilitate the assembly of the ball piston pump, the spherical housing 1 consists of two half shells 1a and 1b, which are joined together by means of flanges 18 and a screw connection 19.

In the illustration according to Fig. 2, the rotary piston 4 and the guide ring 3 are in a position which is to be referred to as the starting position or 0° position. The rotary piston 4 divides the two working chambers 2a and 2b into two delivery chambers 20a and 21a and 20b and 21b. In the 0° position, the chambers 20a and 20b have a maximum volume and the chambers 21a and 21b have a minimum volume. The

Inlet channels 11a and 11b are closed by the vanes 4a and 4b of the rotary piston 4. Also closed are the outlet channels 12a and 12b, which are arranged perpendicular to the plane of the drawing opposite the inlet channels 11a and 11b, but cannot be seen in the illustration according to Fig. 2.

If the drive shaft 8 rotates around the axis 10 in a clockwise direction (right rotation), the guide ring 3 also moves around the axis 9 in the same direction. The chambers 21a and 21b begin to open and suck in medium through the opening inlet channels 11a and 11b. At the same time, the chambers 20a and 20b shrink and the medium in these chambers is pressed out of the opening outlet channels 12a and 12b by the rotary piston 4 rotating around the axes 9 and 10 and oscillating around the axis 14.

In the illustration according to Fig. 3a and Fig. 3b, the guide ring 3 has rotated 90° around its axis of rotation 9. Fig. 3a shows the same section as in Fig. 2 and Fig. 3b a section B-B in a plane perpendicular to it.

The rotary piston 4 with its two wings 4a and 4b divides the working chambers 2a and 2b into two equally large chambers or delivery volumes 20a and 21a and 20b and 21b. The inlet channels 11a and 11b are connected to the chambers 21a and 21b and the outlet channels 12a and 12b are connected to the chambers 20a and 20b.

In Fig. 4, the guide ring 3 has rotated 180° around its axis of rotation 9. The rotary piston 4 has the same position as in Fig. 2, only also rotated 180° around the axis 9. The chambers 21a and 21b have reached their maximum volume and the chambers 20a and 20b are closed (minimum chamber volume).

If the drive shaft 8 now rotates around the axis 10 in a clockwise direction, the process according to Fig. 2 is repeated, but with the delivery chambers 20a, 20b, 21a, 21b swapped.

With one rotation of the guide ring 3 by 360°, medium is sucked in and expelled twice.

Fig. 5 shows the illustration of the guide ring 3 for the rotary piston 4 in plan and side elevation. It essentially consists of a round disk 22 with an opening 23 for receiving the piston guide element 13. The guide ring 3 is surrounded by a bearing ring 24 with which it is rotatably mounted in a groove within the spherical working chamber 2 of the ball piston pump. The bearing ring 24 can be a ball or plain bearing.

Furthermore, an insert 25 is provided in the guide ring 3 for sealingly supporting the rotary piston 4 (Fig. 6) with the piston guide element 13 (Fig. 7).

A suitable form of the rotary piston 4 is shown in Fig. 6. It consists of a flat web 26 and the two wings 4a and 4b. The flat web 26 serves to accommodate the piston guide element 13 (shown in Fig. 7), with which the rotary piston 4 is mounted in the guide ring 3 (Fig. 5).

In the embodiment according to Fig. 6, the rotary piston 4 is provided with a continuous slot 5 for receiving the drive disk 6 (shown in Fig. 8), which divides the rotary piston 4 into two halves. In another embodiment, this slot 5 does not necessarily have to be continuous. For example, a circular ring-shaped connection 27 can be retained in the middle of the rotary piston 4 as a fixed connection between the two rotary piston halves, for receiving a fork-shaped drive disk 6 rotating around this connection 27 (also in

30' Fig. 8).

The piston guide element 13 shown in Fig. 7 serves, in addition to its function as a pivot bearing for the rotary piston 4, at the same time as a sealing element between the two hemispherical working chambers 2a and 2b of the ball piston pump. It

At its ends there is a bearing pin 28 for mounting in the guide ring 3 according to Fig. 5 and a continuous slot 29 for receiving the rotary piston 4. In order to facilitate the assembly of the piston guide element 13, it is also expediently disassembled into two halves, which are held together by the two housing half shells la and lb of the spherical working chamber 2 via the bearing insert 25 in the guide ring 3.

Two possible variants of the drive disk 6 are described in Fig. 8. It can have a substantially round or elliptical disk shape 30 (solid line) or a fork shape 31 (dashed line). In the fork shape 31, the U-shaped curve 32 grips the annular connection 27 in the slot 5 of the rotary piston 4 (shown in Fig. 6). The drive shaft 8 is firmly connected to the drive disk 6.

In addition, other shapes of the drive disk 6 are conceivable in connection with a corresponding design of the milled recess or the slot 5 in the rotary piston 4.

To facilitate rotation of the drive disk 6 in the rotary piston 4, it can either be made of a self-lubricating material, have separate lubrication and/or have embedded balls to reduce friction.

List of reference symbols

Housing of the ball piston pump 1

Housing half shells la and Ib

Working chamber of the ball piston pump 2

hemispherical working chambers 2a and 2b

Guide ring 3

Rotary piston 4

Wings of the rotary piston 4a and 4b

Slot in the rotary piston 5

Drive pulley 6

Flange connection 7

Drive shaft of the ball piston pump 8

Rotation axis of the guide ring 9

Rotation axis of the drive shaft 10

Inlet channels lla and 11b

Outlet channels 12a and 12b

Piston guide element 13

Rotation axis of the piston guide element 14

Rotation axis of the drive disk 15 Hole for the drive shaft 16 Bearing for the guide ring 17 Flanges for connecting the housing half shells 18

Screw connection housing 19

Delivery chamber 1 (2a) 20a and 21a

Delivery chamber 2 (2b) 20b and 21b

Guide ring disc 22

D .;. &lgr;.·■..'"■■·

Breakthrough in the guide ring 23

Bearing of the guide ring 24

Bearing insert guide ring 25

Bridge on rotary piston 26

circular connection in the rotary piston 27

Bearing pin on piston guide element 28

Slot in piston guide element 29

round disk shape of the drive disk 30

Fork shape of the drive disc 31

U-shaped curve in the drive pulley 32

Claims (17)

Protection claims 1. Ball piston pump with a spherical working chamber formed by a housing, at least one separate inlet and outlet for the medium to be pumped and an externally driven rotary piston which alternately enlarges (suction phase) and reduces (discharge phase) the working chamber, characterized in that - the spherical working chamber (2) is divided into two hemispherical working chambers (2a, 2b) by a rotatably arranged guide ring (3), the axis of rotation (9) being perpendicular to the plane of the guide ring (3) and being arranged in a fixed position within the housing (1) of the ball piston pump, - each hemispherical working chamber (2a and 2b) has a separate inlet channel (11a or 11b) and a separate outlet channel (12a or 12b) for the medium to be conveyed, - within the guide ring (3) the rotary piston (4), consisting of two wings (4a, 4b), is arranged so as to be rotatable about an axis (14), in that the plane of the rotary piston (4) intersects the plane of the guide ring (3) in its middle in such a way that one wing (4a) of the rotary piston (4) projects into the first hemispherical working chamber (2a) and the other wing (4b) of the rotary piston (4) projects into the second hemispherical working chamber (2b), and the angle between the plane of the guide ring (3) and the plane of the rotary piston (4) is variable, - the rotary piston (4) has a milled recess or a slot (5) along the plane through its wings (4a, 4b) and divides this symmetrically, partially or completely, &mdash; a drive disk (6) is inserted into the slot (5) of the rotary piston (4), which drive disk (6) is located both inside the *
I Slot (5) is arranged to rotate about an axis (15) perpendicular to the plane of the rotary piston (4) or the drive disk (6) as well as about a fixed axis (10) through the plane of the drive disk (6), wherein the 5 fixed axis (10) of the drive disk (6) is inclined to the axis of rotation (9) of the guide ring (3) by a fixed angle α < 90°, &mdash; the drive disk (6) has a drive shaft (8), which is guided through a bore (16) through the housing (1) of the ball piston pump. 2. Ball piston pump according to claim 1, characterized in that the vanes (4a, 4b) of the rotary piston (4) have the shape of semicircular disks and are so large that they pass closely along the inner wall of the spherical housing (1). 3. Ball piston pump according to claim 1, characterized in that the vanes (4a, 4b) of the rotary piston (4) have a sufficient thickness to accommodate the drive disk (6) and to securely close the inlet and outlet channels (11a, 11b, 12a, 12b) and are provided with a geometry that brings about optimal opening and closing of the working chambers (2a, 2b) or the delivery chambers (20a, 20b, 21a, 21b). Ball piston pump according to claim 3, characterized in that the wings (4a, 4b) of the rotary piston (4) are shaped like shovels. Ball piston pump according to claim 1, characterized in that the seal of the rotary piston (4) to the housing (1) of the ball piston pump and of the piston guide element (13) to the guide ring (3) is a precisely fitting sliding seal. 6. Ball piston pump according to claim 1, characterized in that the sealing of the rotary piston (4) to the housing (1) of the ball piston pump and the piston guide element (13) to the guide ring (3) is carried out by additional sealing lips or strips. 7. Ball piston pump according to claim 1, characterized in that the bearing (17, 24) of the guide ring (3) in the housing (1) of the ball piston pump is a plain or rolling bearing. 8. Ball piston pump according to claim 1, characterized in that the bearing (25, 28) of the piston guide element (13) in the guide ring (3) is a plain or rolling bearing. 9. Ball piston pump according to claim 1, characterized in that the drive disk (6) is mounted with low friction within the rotary piston (4). 10. Ball piston pump according to claim 9, characterized in that the drive disk (6) is coated with a self-lubricating material. 11. Ball piston pump according to claim 9, characterized in that an additional lubricant is introduced into the slot (5) between the drive disk (6) and the rotary piston (4) for the bearing of the drive disk (6). 12. Ball piston pump according to claim 9, characterized in that the drive disk (6) is mounted within the rotary piston (4) by rolling elements similar to a ball bearing It '- and the rolling elements are embedded in the drive disk (6). 13. Ball piston pump according to claim ₁₇ , characterized in that the drive disk (6) has a substantially round or elliptical shape (30). 14. Ball piston pump according to claim 1, characterized in that the drive disk (6) has a fork shape (31). 15. Ball piston pump according to claim 1, characterized in that the slot (5) and the drive disk (6) are designed in such a way that the slot (5) is arranged outside the openings for the inlet and outlet channels (Ha, Hb, 12a, 12b) in every position of the rotary piston (4). 16. Ball piston pump according to claim 1, characterized in that the housing (1) of the ball piston pump consists of two half shells (la, 1b) which are connected by means of a flange connection (7). 17. Ball piston pump according to claim 1, characterized in that at the location of the bore (16) for the drive shaft (8) a circular or ring-shaped control element is inserted into the housing (1) in a pressure-tight and rotatable manner, with which the angle α between the stationary axis (10) of the drive disk (6) and the axis of rotation (9) of the guide ring (3) can be changed to control the delivery rate.