Rotary piston pump

Abstract

The invention relates to a rotary piston pump (1) comprising in a spherical inner chamber (3) of a pump housing (2) with suction and pressure sides, a pair of rotary pistons (4, 5) in the form of universal-joint forks (6, 7) and a cross (8), between said forks (6, 7). The forks (6, 7) of the rotary pistons (4, 5) mesh with the cross (8) between them and form four pump chambers of variable volume when the rotary pistons (4, 5) and the cross (8) between are rotated. Each rotary piston (4, 5) is attached centrally to a hollow support shaft (13, 13', 14, 14') through a conical joint (10) and is fixed in place with a bolt joint (16) extending through a cavity (15) of the support shaft, where said support shaft is equipped with bearings (11, 12) and sealed.

Description

[0001] Rotary piston pump

[0002] TECHNICAL FIELD

[0003] The invention relates to a positive displacement pump, more specifically a spherical rotary piston pump.

[0004] BACKGROUND ART

[0005] The Estonian utility model EE00122U1 (published 15 October 1997) discloses a rotary piston pump comprising in a spherical inner chamber of a pump housing with suction and pressure sides, a pair of rotary pistons, in the form of universal-joint forks, and a cross between the forks. The forks of the rotary pistons mesh with the cross between them and form four pump chambers of variable volume when the pair of rotary pistons and the cross between them are rotated.

[0006] One of the major technical problems with rotary piston pumps are the bearings and seals of the rotary piston pairs, because their working capacity usually becomes exhausted before the other pump parts.

[0007] This usually means replacing the entire pump. In reality, however, the other parts of the pump are able to continue working. In addition, the rotary pistons of the pump are usually made of stainless steel, which is troublesome to cut, especially considering its external spherical surface. The rotary pistons are located in a spherical piston chamber within the pump housing, making it troublesome, time-consuming and relatively expensive to prepare accurately and in a suitable fit to allow the piston to rotate freely but with sufficient density to pump a flowing medium.

[0008] Therefore, there is a need for a design in which the bearings and seals of the rotary pistons of the pump can be easily repaired and / or replaced if necessary. This would allow the full working capacity of the other parts of the pump to be utilized and significantly reduce the costs associated with pumping fuels, oils, water, and waste water, for example.

[0009] The present invention is directed at solving the problems described above.

[0010] SUMMARY OF INVENTION

[0011] The present invention proposes a rotary piston pump comprising, in a spherical inner chamber of a pump housing with suction and pressure sides, a pair of rotary pistons, in the form of universal-joint forks, and a cross between the forks. The forks of the rotary pistons mesh with the cross between them and form four pump chambers of variable volume when the pair of rotary pistons and the cross between them are rotated. The rotation axes of the rotary pistons are intersecting and are both located in the dividing plane of the pump housing.

[0012] Each rotary piston is attached by a conical joint to a hollow support shaft by a central bolt joint extending through a cavity of the support shaft, which is sealed (gasketed) and supported on bearings, wherein at least one of the said support shafts is configured to be driven by an electric motor.

[0013] In a preferred embodiment of the invention, each of said support shafts together with the bearings are located in a separate support housing.

[0014] At least one of the support housings is connected to the pump housing by a flanged joint.

[0015] In the first embodiment of the invention, a stator of the electric motor is integrated into at least one of said support housings, with the stator of the electric motor surrounding a rotor of electric motor, which is stationary on said support shaft.

[0016] In the second embodiment of the invention, at least one of said hollow support shafts extends out of the other end of the support housing and is connected to the electric motor.

[0017] In a third embodiment of the invention, a stator of the electric motor is integrated into both said support housings, the stator of the electric motor surrounding a rotor of electric motor, which is stationary on said support shaft.

[0018] This solution allows the bearings and seals (gaskets) to be replaced without dismantling the rotary pistons and the pump housing comprising the cross.

[0019] In addition, this solution is modular, as depending on the density (viscosity) of the medium to be pumped, it is possible to equip both rotary pistons with an electric motor as required, using the same pump housing, in which one electric motor is used to drive the pump by only one rotary piston.

[0020] The use of two electric motors also reduces the friction between the cross, located between the rotary pistons, and the forks of the rotary piston compared to using only one electric motor. It also reduces the load on bearings. This, in turn, reduces wear on these parts and extends the working capacity of the whole pump. BRIEF DESCRIPTION OF DRAWINGS

[0021] The invention is described below with reference to the accompanying schematic drawings, where:

[0022] Figure 1 shows an axonometric view of the first embodiment of the invention, in which one support shaft and its support housing are integrated with an electric motor;

[0023] Figure 2 shows the rotary piston pump corresponding to Figure 1 with one side of the pump housing removed;

[0024] Figure 3 shows a longitudinal section of the rotary piston pump corresponding to Figures 1 and 2;

[0025] Figure 4 shows an enlarged detail view of the longitudinal section in Figure 3 with the support housings attached to the pump housing;

[0026] Figure 5 shows an axonometric view of the second embodiment of the invention in which both support shafts and their support housings are integrated with an electric motor;

[0027] Figure 6 shows the rotary piston pump corresponding to Figure 5 with one side of the pump housing removed;

[0028] Figure 7 shows a longitudinal section of the rotary piston pump corresponding to Figures 5 and 6;

[0029] Figure 8 shows an enlarged detail view of the longitudinal section in Figure 7 with the support housings attached to the pump housing;

[0030] Figure 9 shows an axonometric view of the third embodiment of the invention, in which a support shaft and its support housing are adapted so the support shaft can be connected to an electric motor;

[0031] Figure 10 shows the rotary piston pump corresponding to Figure 9 with one side of the pump housing removed;

[0032] Figure 11 shows a longitudinal section of the rotary piston pump corresponding to Figures 9 and 10. DESCRIPTION OF EMBODIMENTS

[0033] For the sake of clarity, the same parts and elements in different figures are indicated with the same reference numbers.

[0034] In the first, second and third embodiments according to the invention, shown respectively in Figures 2, 6, and 10 with one side of the pump housing 2 removed, of the rotary piston pump 1 shown in Figures 1 , 5, and 9, the design of the spherical inner chamber 3 of the pump housing 2 is the same.

[0035] In all embodiments, the rotary piston pump 1 comprises, in the spherical inner chamber 3 of the pump housing 2 with suction and pressure sides, rotary pistons 4 and 5 in the form of universal-joint forks, and a cross 8 between the respective forks 6 and 7 of the rotary pistons 4 and 5, with the cross 8 having a spherical section 9 in the middle of its arms.

[0036] The rotational axes of rotary pistons 4 and 5 are both located in the dividing plane of the pump housing 2, but the rotational axes intersect at an angle. The forks 6 and 7 of the rotary pistons 4 and 5 mesh with the cross 8 between them and rest against the spherical section 9 in the middle of the arms of the cross 8.

[0037] Each rotary piston 4, 5 is attached by a conical joint 10 to a hollow support shaft 13 and 14 by a central bolt joint 16 extending through a cavity 15 of the corresponding hollow support shaft 13 and 14. At least on the side of the rotary pistons 4 and 5, the ends of the support shafts 13 and 14 are sealed (gasketed) with a seal 17.

[0038] In the first embodiment of the invention, in Figures 1 to 4, the support shaft 13 and its support housing 18 are integrated with an electric motor, i.e. the support housing 18 has an integrated stator 19 of the electric motor surrounding a rotor 20 of the electric motor on the support shaft 13. In this embodiment, the support shaft 13 is a drive shaft, at the end of which a rotary piston 4 rotates both the second rotary piston 5 as well as the cross 8 between the rotary pistons 4 and 5. In principle, this design can be considered a hollow shaft electric motor with a conical joint 10 at the end of the shaft for connecting a rotary piston 4 or 5.

[0039] In the embodiment shown in Figures 1 to 11 , the support housing 18 integrated with the electric motor is connected to the pump housing 2 by a flanged joint 21 .

[0040] In the first embodiment of the invention, the support shaft 14 of the second rotary piston 5 is located in the support housing 22 on bearings 11 and 12, wherein on the side of the rotary piston 5 the support shaft 14 is sealed by a seal 17. The other end of the support housing is closed and in the embodiment shown in Figures 1 to 3, it is closed with the end cover 23.

[0041] As can be seen in Figures 3 and 4, the portions of the support shafts 13 and 14 and the support housings 18 and 22 extending into the pump housing 2 are exactly the same in shape and design.

[0042] The conical joints 10 and bolt joints 16 on the support shafts 13 and 14 are identical and suitable for receiving and securing both rotary pistons 4 and 5.

[0043] The second embodiment of the invention shown in Figures 5 to 8 differs from the first embodiment shown in Figures 1 to 4 only in that both support shafts 13 and 13’ and their support housings 18 and 18’ are integrated with an electric motor and have exactly the same design, and therefore, in order to distinguish them, the second support shaft is marked with reference number 13’ and the second support housing with reference number 18’. As all the parts included in them are exactly the same, the same reference numbers have been used for them.

[0044] This embodiment is suitable for pumping more viscous and therefore more difficult to pump liquids. As both rotary pistons 4 and 5 are driven separately by the corresponding support shaft 13 and 13’, the friction between the respective forks 6 and 7 of the rotary pistons 4 and 5 and the cross 8 is reduced, thus reducing wear on these parts.

[0045] The third embodiment of the invention shown in Figures 9 to 11 differs from the first embodiment shown in Figures 1 to 4 in that the electric motor is not integrated in the support housing 18’, but the end of the support shaft 14’ located in said support housing 18’ extends out of the end cover 24 of the support housing 18’ to be connected to the electric motor. Otherwise, the design of the support shafts 14 and 14’ and the support housing 18 and 18’ is the same.

[0046] The second support shaft 14 and support housing 18 have exactly the same design as in the first embodiment of Figures 1 to 4.

[0047] The invention is not limited to embodiments depicted in the drawings nor to the embodiments described above, but other embodiments of the invention are possible within the scope of the enclosed claims. LIST OF REFERENCE NUMBERS

[0048] 1 - rotary piston pump

[0049] 2 - pump housing

[0050] 3 - spherical inner chamber

[0051] 4 - rotary piston

[0052] 5 - rotary piston

[0053] 6 - fork of a rotary piston

[0054] 7 - fork of a rotary piston

[0055] 8 - cross

[0056] 9 - spherical section in the middle of the arms of the cross

[0057] 10 - conical joint

[0058] 11 - bearing

[0059] 12 - bearing

[0060] 13, 13’ - support shaft

[0061] 14 - support shaft

[0062] 14’ - support shaft

[0063] 15 - cavity

[0064] 16 - bolt joint

[0065] 17 - seal

[0066] 18, 18’ - support housing

[0067] 19 - stator of electric motor

[0068] 20 - rotor of electric motor

[0069] 21 - flanged joint

[0070] 22 - support housing

[0071] 23 - end cover

[0072] 24 - end cover

Claims

CLAIMS1. A rotary piston pump (1 ) comprising in a spherical inner chamber (3) of a pump housing (2) with suction and pressure sides, a pair of rotary pistons (4, 5) in the form of universal-joint forks (6, 7) and a cross (8) between said forks (6, 7), wherein the forks (6, 7) of the rotary pistons (4, 5) mesh with the cross (8) between them and form four pump chambers of variable volume when the rotary pistons (4, 5) and the cross (8) between them are rotated, wherein the rotation axes of the rotary pistons (4, 5) are intersecting and are both located in a splitting plane of the pump housing (2), characterized in that each rotary piston (4, 5) is attached by a conical joint (10) to a hollow support shaft (13, 13’, 14, 14’) by a central bolt joint (16) extending through a cavity (15) of the support shaft (13, 13’, 14, 14’), which is sealed and supported on bearings (11 , 12), wherein at least one of the said support shafts (13, 13’, 14’) is configured to be driven by an electric motor.

2. The rotary piston pump (1 ) according to claim 1 , characterized in that each of said support shafts (13, 13’, 14, 14’) is located together with bearings (11 , 12) in a support housing (18, 18’, 22).

3. The rotary piston pump (1 ) according to claim 1 or 2, characterized in that at least one support housing (18, 18’, 22) is connected to the pump housing (2) through a flanged joint (21 ).

4. The rotary piston pump (1 ) according to claim 1 , 2, or 3, characterized in that a stator (19) of the electric motor is integrated into at least one of said support housings (18, 18’), with the stator (19) of the electric motor surrounding a rotor (20) of the electric motor, which is stationary on said support shaft (13, 13’).

5. The rotary piston pump (1 ) according to claim 1 , 2, or 3, characterized in that at least one of said hollow support shafts (14’) extends out of the other end of the support housing (22) to be connected to an electric motor.

6. The rotary piston pump (1 ) according to claim 1 , 2, or 3, characterized in that a stator (19) of the electric motor is integrated into both of said support housings (18, 18’), with the stator (19) of the electric motor surrounding a rotor (20) of the electric motor, which is stationary on the support shaft (13, 13’).

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