Maintenance-friendly wobble plate pump

Description

FIELD OF THE INVENTION

[0001] The present invention relates to pumps, more exactly to pumps for matter of high viscosity and specifically pumps, that translate a rotating drive without crank mechanism into fluid conveying.

[0002] Swash plate pumps are quite well known in the art, since it is the most simple form of transferring the rotation of a motor into a conveying movement of liques-cent matter.

[0003] However, most swash plate pumps do not agitate their matter directly, since with fluids of low viscosity the necessary clearance between plate and housing will be too wide for providing acceptable leak tightness. Thus with most swash plate pumps the plate only actuates pistons as maim pumping elements, that work on separate cylinders.

[0004] However, with highly viscous matter to be transported, the swash plate alone can be applied, providing high efficiency, and - compared to piston pumps - with the advantage of low noise and vibration and particularly with low shear on the matter involved. Such pumps are known for example from DE 201 01 861 U1 and US 1 984 447.

[0005] PCT / US82 / 01228 shows another pump with a somewhat different design, comprising split body sections. More specifically, the body sections, one comprising the fluid inlet, the other one the fluid outlet, split the pump body along inclined faces into two parts. Another pump with a body split along a plane being inclined against the rotational axis is known from US2015 / 0 004 037 A1

[0006] Within these groups of pumps, development always aimed at enhancing the efficiency by reducing the clearances between plate and housing without risking blockages.

[0007] With low viscous matter to be pumped, as is pulp, feces or industrial sumps, the risk of debris contained therein is high, since adequate filtering is not always feasible.

[0008] Therefore jams and blockage are comparatively frequent.PROBLEMS TO BE SOLVED

[0009] The constructions of these types of swash plate pumps however involve an orbicu-lar pump volume and a swash plate with eccentric movement therein.

[0010] With a straight vertical partition through the pump volume - as usually applied - shaft and eccentric mechanism of the pump have to be completely dismounted for to disengage the housing parts to remove debris and clearing the pump volume and swash plate, which tends to be a tedious task.

[0011] It therefore is one objective of the here disclosed invention to ease up service by an easily dismountable system.

[0012] Another object of this invention is to simplify the production of the pumping chamber. As up to actual designs the movement of the plate piston has to shift a partial volume of the pump chamber between two separated chamber volumes, the parted chamber needs to have an outline with a protrusion, against which a flat swash plate must be pressed, so to effectively fulfil its pumping.

[0013] However, such a protrusion provokes undercuts in the geometry of the pump housing, which therefore is intricate to produce. Moreover, plane plates are rather prone to get jammed at eccentric movement within a rounded chamber, even if its rim is congruently shaped to it.TASK OF THE INVENTION

[0014] It therefore is the task of the here disclosed invention, to find a simpler and better maintain- able construction of a direct action swash plate pump.FUNCTIONAL DESCRIPTION OF A INTEGRAL SWASH PLATE PUMP

[0015] A swash plate pump of the here described integral type (so the swash plate is not actuating secondary pistons in their housings) relates to a machine having an annular piston with a swash-like movement, that moves in a spherical working chamber.

[0016] The necessary separation of the spherical working chamber into an input and an output volume is accomplished by a separation wall (further below called sword) that reaches from the top-middle section of the working chamber unto the center of the ball on the turning shaft, which guides the piston or swash ring in a circum-ferral groove .

[0017] The swash plate necessarily has to have a radial recess, which is running along to the blade. This prevents co-rotation of the swash plate, but allows its inclination , so to transform the rotational movement of the axis into a waggling motion of the swash plate, which shovels the input volume over to the output.

[0018] The amplitude of the swashing motion thereby results from an angular offset of the bearing of the swash plate to the input and output shaft axis, which may be in a range of about 5° to about 45°.

[0019] The piston machine can be used both as a pump and as a generator. To be particularly effective for the function as a pump, a bending angle of about 30° has been found best.

[0020] The outer rim of the swash-type piston needs to be shaped correspondingly to the spherical outer shape of the working chamber with the smallest clearance given to move without blocking. Together with the sword's clearance to the ball these two parameters mostly determine the efficiency of the system.PROBLEMS TO BE SOLVED

[0021] Due to the swashing movement of the piston in the spherical chamber, the complete drive axis has to be dissembled in most service cases, since otherwise the housing could not be taken apart. So hitherto it is impossible to dismount this type of gear without knocking it down to bits and pieces.

[0022] Another problem is given in the production process of the working chamber. For to effectively displacing the chamber volume, the shape of the chamber has to be a spherical segment ending in inclined separation walls, as to be seen in Fig. 2b. However, this shape implies back taperings, which are intricate to be produced. A further problem of this kind of machines is a tendency of blocking, when debris may be pinched between the rim of the squash plate and the walls of the working chamber.SOLUTION

[0023] The inventive step to solve these problems is threefold: In a basic embodiment of the invention the housing of said machine is separated with a bevelled cut whilst the cutting plane runs through the center of the ball (see cutting line 28 through the housings 1 in Fig. 1 and Fig. 2a and 2b).

[0024] The idea therefore is to maintain the metal housing rectangular and easily to be cast, but to bevel the separations between a pump head and the rest of the casing, so that the head part of the housing can be removed to get access to the pump chamber without dismounting the axis and the eccentric tappet.

[0025] Moreover, the input and output parts of the working chamber, that feed or are fed into input- and outlet ports (3 and 4 in Fig. 1), are radially arranged to the housing. This makes it possible to dismount the machine top at a proper position of the driving shaft without further dismantling it - as demonstrated in the exploded drawing Fig. 1 - so that the working chamber gets accessible for cleaning quite easily and there is no necessity to detach the media connections and input or output shaft with seal and bearings in case of service.

[0026] In a second embodiment the piston is transformed into a swash plate with bevelled contour, which would allow the plate to be suspended against a vertical edge of the pump chamber. Therefore the working chamber could be designed with perpendicular walls on its front and back side (26 on Fig. 2a in comparison to 22 in Fig. 2b). With this shape, machining the working chamber is much more easily to be done, since there are no more back taperings.

[0027] Moreover, the separating sword (9 in Fig. 1) is easily detachable with its base plate 8, so not to hamper the ball parts 5 and 10 to be taken off, and a conical recess 7 in the swash plate matches the shape of a thickening on the sword's edges (9 on Fig. 1 ). This is necessary for properly guiding of the swash plate (6a in Fig. 2a), which is considerably thicker than in conventional systems 6b, shown in Fig. 2b. However, this shape of the sword also allows to put on a somewhat flexible sealing of self-lubricating plastic, possibly inserted into a keyway within the sword's arch.

[0028] The advantage of said shape of a swash plates is, that due to their rigid geometry, softer materials can be applied instead of steel etc., which makes it possible to use plastic material with self-lubricating properties to be bevelled down to a small rim (18 on Fig . 1), that would not be prone to blockages.

[0029] The arrangement of the parting plane of the two-part housing, perpendicular to the bearing axis of the swash ring in a fixed rotational position, further allows the head of the working space and the swash ring to be disassembled without taking the machine apart.

[0030] Due to the low number and the smooth surface shape of the wetted parts as well as the extremely gentle way of movements almost without crushing and shearing, the machine is functioning as a pump particularly, but not exclusively, suitable for use in chemical and biochemical area. In promoting fluid and viscous foods which may also contain solids, all wetted areas of the pump can be easily disinfected by a cleaning flush.DETAILED DESCRIPTION OF THE INVENTION ALONG TO THE DRAWINGS:

[0031] In Fig.1 a swash plate pump is illustrated, wherein a drive shaft 19 moves a swash plate 6 about a swash point 20, so as to describe a double conical surface. The swash point 20 coincides with the center point of the spherical surface 6 of the swash plate and the spherical inner surface of the pump chamber 17. The pump housing 1 is split from the pump head 2 at a bevelled cut 28. The drive shaft 19 turns the eccentric split ball, consisting of the parts 5 and 10, thereon the swash plate 6 would turn, would it not be restricted to a wagging movement by the sword 9, which holds the swash plate 6 in its recess 7. The shaft is then suspended in the end bearing 16 on the front plate 2, travelling through its sub-parts 11 and 12, whereas the front part 2 and the housing 1 are sealed with the O-ring 14.

[0032] It is to be seen, that the input and output ports 3 and 4 are mounted radially to the axis. This, compared to other constructions, allows to dismount the head without disassembly of intake and exhaust.

[0033] Fig 2a and 2b are simplified longitudinal cuts which should exemplify the difference between the shape of the pump housing 1 in prior art on Fig. 2b and on the here disclosed invention in Fig. 2a. Whereas the swash plate 6b in Fig. 2b is flat and the shape of the working chamber has protrusions 21 to 24, the swash plate 6a in Fig. 2a is bevelled and the front and aft walls of the working chamber 25 and 26 are flat, but the resulting working volume 27 a and 27b are almost identical. But the housing 1 in Fig. 2a obviously is much easier to be fabricated.

Claims

1. A swash plate pump for direct transfer of viscous media from an input to an output port (3, 4) with a split two-part housing (1, 2), wherein the split two-part housing comprises a pump housing (1) split from a pump head (2), wherein a drive shaft (19) is turning an eccentrically split ball (5, 10), on which a swash plate (6) having an outer rim shaped correspondingly to a spherical inner shape of the pump chamber is arranged, thus resulting in a wagging movement of the swash plate (6) inside a pump chamber (17), wherein the wagging movement of the swash plate (6) is limited by a sword (9) which holds the swash plate (6) in a recess of the swash plate, so that the drive shaft (19) moves the swash plate (6) about a swash point (20) so as to describe a double conical surface, the swash point being at the same time the center point of the surface of the outer rim of the swash plate (6) and the spherical inner surface of the pump chamber (17) and of the split ball (5, 10), characterized in that the parting plane (28) of the split housing (1, 2) is bevelled by an angle in a range of 5° to 45° relative to an axis perpendicular to the drive shaft (19), said parting plane (28) running through the center of the ball (5, 10) and wherein the input and output ports (3, 4) are mounted at the pump housing (1).

2. Swash plate pump as to claim 1, comprising a bevelled swash plate and a pump chamber with straight front and back planes.

3. Swash plate pump as to claim 1 and 2, comprising input and output ports arranged radially to the drive shaft axis on the pump housing (1).

4. Swash plate pump as to one of the preceding claims, wherein the swash plate (6) comprises a conical recess at its upper rim that matches the shape of a thickening on the sword's edges at different angular positions.