GB2290583A

GB2290583A - Pump

Info

Publication number: GB2290583A
Application number: GB9412781A
Authority: GB
Inventors: Peter Robin Wilkinson
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-06-24
Filing date: 1994-06-24
Publication date: 1996-01-03
Anticipated expiration: 2014-06-24
Also published as: GB2290583B; GB9412781D0

Abstract

A pump comprises a housing 1 having a circular cylindrical cavity 2, inlet and outlet ports 3, 4 in the cylindrical wall 5 of the cavity and a bearing bore 6 co-axial with the cavity 2. A rotary block 11 occupies the cavity 2 and has a drive shaft 12 extending from the cavity via the bearing bore, where it is supported in a journal bearing 13. A circular cylinder 14 in the block 12 is arranged transversely of the drive shaft 12 and receives a piston 21, the latter being reciprocatingly arranged and provided with a transverse slot 22 at its mid-length. An end plate 31 closes the housing 1 and supports an eccentric pin 41 received in the transverse slot 22, whereby rotation of the shaft 12 causes the piston to reciprocate. A bearing 51 in the form of an L-section ring has its larger diameter fitted into a recess in the end plate 31 and its smaller diameter filled into a bore 54 in the end face 55 of the rotary block 11. The bearing functions as a journal bearing and as a thrust bearing. <IMAGE>

Description

PUMP The present invention relates to a pump having a piston reciprocating in a rotary block.

Such a pump is known from my British Patent Application No. 2,188,102 ("My Earlier Application"). Generally it comprises: a housing having a circular cylindrical cavity, inlet and outlet ports in the cylindrical wall of the cavity and a bearing bore co-axial with the cavity; a rotary block occupying the cavity and having a block drive shaft extending from the cavity via the bearing bore and a circular cylinder arranged transversely of the drive shaft; a piston reciprocatingly arranged in the cylinder within the block, the piston having a transverse slot at its mid-length; an end plate enclosing the rotary block in the housing and a stationary piston drive pin supported in the end plate and arranged to engage in the transverse slot, the pin being on the side of the rotary block opposite from the block drive shaft and eccentric with respect to the shaft;; the arrangement being such that on rotation of the shaft, the block turns and carries the piston around with it, the drive pin describes a reciprocating movement with respect to the cylinder and constrains the piston to reciprocate in the cylinder.

I have discovered that the pump described in My Earlier Application ("My Earlier Pump") is susceptible to wear and resultant leakage around the periphery of the rotary block.

I believe that this is due to flexure of its components, especially when the housing and the rotary block are of plastics materials.

Now I have improved the pump by supporting the rotary block at its eccentric drive pin side.

In accordance with my improvement, I provide in My Earlier Pump a bearing between the rotary block and the end plate.

Preferably the bearing is arranged both as a journal bearing and as a thrust bearing. Arrangement as a thrust bearing enables a seal at the shaft side of the rotary block to be a face seal acting on the block.

In a further improvement, I provide a slide between the eccentric pin and the piston to spread the load on the piston.

To help understanding of my invention, a specific embodiment thereof is now described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional side view of a pump of my invention, taken on the line I-I in Figure 2; Figure 2 is a cross-sectional end view taken on the line II-II in Figure 1; Figure 3 is a cross-sectional end view taken on the line III-III in Figure 1; and Figure 4 is view similar to Figure 1 with the pump's rotor turned through 900.

Referring now to the drawings, the pump has: a housing 1 having a circular cylindrical cavity 2, inlet and outlet ports 3,4 in the cylindrical wall 5 of the cavity and a bearing bore 6 co-axial with the cavity 2; a rotary block 11 occupying the cavity 2 and having a block drive shaft 12 extending from the cavity via the bearing bore, where it is supported in a journal bearing 13, and a circular cylinder 14 arranged transversely of the drive shaft 12; a piston 21 reciprocatingly arranged in the cylinder 12 within the block 11, the piston having a transverse slot 22 at its mid-length; an end plate 31 enclosing the rotary block 11 in the housing 1 and a stationary piston drive pin 41 screwed into

the end plate 31, fixed by a lock nut 42 and arranged to engage in the transverse slot 22 in the piston 21, the pin being eccentric with respect to the shaft 12;; the arrangement being such that on rotation of the shaft 12, the block 11 turns and carries the piston 21 around with it; the drive pin 41 describes a reciprocating movement with respect to the cylinder 14 and constrains the piston 41 to reciprocate in the cylinder.

These features are similar to their equivalents in My Earlier Application.

The pump includes the following features in accordance with my present improvement: a bearing 51 in the form of an L-section ring having a radial face 52 and an axial face 53, the ring being fitted to a recess in the end plate 31. The rotary block 11 has a bore 54 in its end face 55 (through which the pin 41 engages the piston 21.) The bearing's axial face 53 abuts the end face 55 and supports the rotary block as a thrust bearing.

Further, the bearing's radial face 52 engages in the bore 54 and supports the rotary block as a journal bearing, particularly against the pressure in the outlet port 4 of the fluid being pumped.

The provision of the thrust bearing enables a face seal 56 to be installed in the bore 6 to act on the opposite face 57 of the rotary block 11.

Further between the pin 41 and the transverse slot 22 in the piston 21, a slide 58 is provided to spread the load on the piston in its slot.

It should be noted that although Figure 3 shows the pin to be in the vertical plane through the inlet and outlet ports, in practice the timing of the pump will be adjusted by clockwise rotation of the end plate as shown in Figure 3.

Claims

CLAIMS:

1. A pump comprising: a housing having a circular cylindrical cavity, inlet and outlet ports in the cylindrical wall of the cavity and a bearing bore co-axial with the cavity; a rotary block occupying the cavity and having a block drive shaft extending from the cavity via the bearing bore and a circular cylinder arranged transversely of the drive shaft; a piston reciprocatingly arranged in the cylinder within the block, the piston having a transverse slot at its mid-length; an end plate enclosing the rotary block in the housing and a stationary piston drive pin supported in the end plate and arranged to engage in the transverse slot, the pin being on the side of the rotary block opposite from the block drive shaft and eccentric with respect to the shaft; ; the arrangement being such that on rotation of the shaft, the block turns and carries the piston around with it, the drive pin describes a reciprocating movement with respect to the cylinder and constrains the piston to reciprocate in the cylinder; wherein the pump is provided with: a bearing between the rotary block and the end plate.

2. A pump as claimed in claim 1, wherein the bearing is arranged both as a journal bearing and as a thrust bearing.

3. A pump as claimed in claim 2, including a seal at the shaft side of the rotary block in the form of a face seal acting on the block.

4. A pump as claimed in claim 1, claim 2 or claim 3, including a slide between the eccentric pin and the piston to spread the load on the piston.

5 A pump substantially as hereinbefore described with reference to the accompanying drawings.