GB2363827A - Hand operated vacuum pump - Google Patents

Abstract

A hand operated vacuum pump comprises a pumping cylinder 1, a forward end cap 2 having an inlet port 3 containing a first one-way valve, a piston 5 fitted with a sealing washer 7 and containing a second one-way valve (25 figure 2a), a piston driving shaft 6, spring means to urge the piston forward, a lever 9 having one end located in slot 11 of the piston driving shaft 6 and mounted on a fulcrum attached to a handle 4. Squeezing the lever draws the piston driving shaft rearwards against the force of the spring whereby air is drawn through the first one-way valve. When released the spring returns the piston allowing any air, in the cylinder to exit through the second one-way valve. The cylinder and handle may be moulded as a single unit which, together with the end cap, the rear sealing cap, the lever and fittings, may be moulded from ABS copolymer. The ABS copolymer components maybe fitted together by treating the abutting surfaces with a solvent. The piston may be moulded from high density polyethylene. The pump may have metal components which may be made from stainless steel or a corrosion resistant alloy.

Description

2363827 VACUUM PUMP This invention relates to a novel hand operated vacuum

pumps having improved pumping efficiency and vacuum holding ability.

Hand operated vacuum pumps are useful devices for many purposes were a low level vacuum is needed and electrical or mechanical power is unavailable or its use inconvenient.

Applications exist in the mechanical field where such pumps can be used to drain hydraulic braking systems on vehicles.

The also exist in the medical field where vacuum chambers are used to induce penile erection.

Existing hand operated pumps have been found to have poor vacuum retention and provide inefficient pumping action The present invention provides a vacuum pump which acts with high efficiency and retains its vacuum for long periods.

According to the present invention there is provided a hand operated vacuum pump comprising a pumping cylinder having an inlet port containing a first one-way valve, a piston fitted with sealing washer and containing a second one-way valve, a piston driving shaft carrying spring means to urge the piston forward, a lever having one end linked to the piston driving shaft and mounted on a fulcrum attached to a handle whereby manual squeezing of the lever draws the piston driving shaft rearwards against the force of the spring whereby air is drawn through the first one-way valve and when released the spring returns the piston allowing any air in the cylinder to exit through the second one-way valve.

The major components of the pump can be injection moulded These comprise the cylinder, end cap, handle, lever, piston and rear sealing cap In a preferred construction the rigid components are moulded from ABS copolymer These include the cylinder and handle, moulded as a single unit, the end caps and lever and fittings The piston, which requires some resilience in the head flanges, is moulded from high density polyethylene The moulding compositions may be pigmented and/or contain suitable fillers.

During assembly the components are fitted together and those moulded from ABS sealed together by treating the abutting surfaces with a solvent for the copolymer.

The design minimises the use of metal which can corrode in moist environments and in many medical situations Where metal is used, such as for the spring means, stainless steel is preferred A release valve or a vacuum limiting valve may be fitted to the inlet port so that any vacuum created may be relieved manually or automatically The metallic components of either valve should be made of stainless steel or another corrosion resistant alloy.

In order to increase the efficiency of the reciprocal motion transmitted to the piston driving shaft by the lever the driving end, in a preferred embodiment, is fitted into a slot in the shaft and the abutting surface has a surface contoured to provide rolling rather than sliding contact with the inner surface of the slot.

In order that the invention may be clearly understood it will now be described with reference to the accompanying drawings, in which:

Figure 1 is an exploded view of a hand pump in accordance with the invention, Figure 2 a is a side view and 2 b a cross section of the piston and shaft forming part of the pump shown in Figure 1, Figure 3 a is a side view cross section and 3 b a top view of the sealing washer fitted within the piston shown in Figure 2, and Figure 4 is a side view of the lever forming part of the pump shown in Figure 1, A hand pump according to the invention, see Figure 1, consists of a pumping cylinder 1 a forward end cap 2 having an inlet port 3 and a first one-way valve (not shown) The cylinder 1 has an integrally moulded handle 4 A piston 5 carried by a shaft 6 matches the bore of the cylinder 1 and is fitted with a sealing washer 7 to ensure leak free suction when the piston 5 reciprocates The washer 7 and piston 5 contain a second one-way valve (not shown) The shaft 6 can move reciprocally through a central aperture in a rear end cap 8.

A lever 9 has a driving end 10 which fits in a slot 11 in the shaft 6 The lever 9 moves about bearing formed by a pair of rivets 12 set in a fulcrum extension 13 forming part of the handle 4 Manual squeezing of the handle 4 towards the lever 9 moves the piston 5 rearwards from the forward end cap 2 so that air is drawn through the inlet port 3 through the first one-way valve If the port 3 is connected to a closed container it will be evacuated When the handle 4 and lever 9 are released a compression spring (not shown) around the shaft 6 urges the piston 5 forwards in the cylinder 1 to the end cap 2 Any air in cylinder 1 will be prevented from entering the port 3 by the first one-way valve and will exit through the second one-way valve provided within the piston 5 and washer 7.

The end cap 2 carries ports 14 and 15 at right angles to each other Port 14 contains a release valve, such as a Schraderhvalve (not shown), having an attached cap 14 which acts as a vacuum release button when pressed by acting on the pin of the valve Port 14 may alternatively carry a vacuum limiting valve, such as a conventional ball and spring valve, which allows air to enter from the outside when the internal pressure falls below a preset value The port 15, shown sealed, may be threaded internally for attachment of a pressure gauge showing the degree of vacuum obtained.

The piston 20, see Figures 2 a and 2 b, has a shaft 21 which carries a driving slot 22 at the end remote from the piston The shaft 21 is preferably formed as a solid member from a resilient material so that the tapered edge of the piston head 24 is urged towards the inner wall of the cylinder in which it is inserted and forms a tight seal Offset from the centre of the piston head is an aperture 25 which forms part of a one-way valve.

In order to improve the seal made by the edge 23 of the piston it is backed by a sealing washer, see Figures 3 a and 3 b, which is passed up the shaft 21 and forced into the cavity 27 below the piston head 20 Both the piston and the sealing washer are made from high density polyethylene to provide the necessary resilience for a tight seal with the cylinder wall.

The operating lever 30, see Figure 4, has a holding surface 31 contoured to fit the inside of a hand The driving end 32 of the lever 30 has a contoured bearing surface 33 which abuts the inner surface of the driving slot 22 in the piston driving shaft 21 The contour of the surface 33 reduces the rubbing friction at the point where the lever abuts the inner surface of the slot 22 and provides a substantially rolling action The lever 30 pivots about a fulcrum point formed by an aperture 34 on bearings, not shown, provided by a pair of rivets which attach the lever 30 to the handle on the main body of the pump.

Claims (11)

1 A hand operated vacuum pump comprising a pumping cylinder having an inlet port containing a first one-way valve, a piston fitted with a sealing washer and containing a second one-way valve, a piston driving shaft carrying spring means to urge the piston forward, a lever having one end linked to the piston driving shaft and mounted on a fulcrum attached to a handle whereby manual squeezing of the lever draws the piston driving shaft rearwards against the force of the spring whereby air is drawn through the first one-way valve and when released the spring returns the piston allowing any air in the cylinder to exit through the second one-way valve.

2 The pump as claimed in claim 1 in which the cylinder and handle are moulded as a single unit.

3 The pump as claimed in claim 1 or claim 2 in which the cylinder and handle, the end cap, the rear sealing cap, the lever and fittings are moulded from ABS copolymer.

4 The pump as claimed in any of the preceding claims in which the piston is moulded from high density polyethylene.

The pump as claimed in claim 3 in which the components moulded from ABS copolymer are fitted together by treating the abutting surfaces with a solvent for the copolymer.

6 The pump as claimed in any of the preceding claims in which the metal components are made from stainless steel or a corrosion resistant alloy.

7 The pump as claimed in any of the preceding claims in which the inlet port is fitted with a release valve enabling any vacuum created to be relieved.

8 The pump as claimed in any of the preceding claims 1 to 6 in which the inlet port is fitted with a vacuum limiting valve preventing the vacuum exceeding a predetermined level.

9 The pump as claimed in any of the preceding claims in which the motion transmitted to the piston driving shaft by the lever driving end is fitted into a slot in the shaft and the abutting surface is contoured to provide a rolling contact with the inner surface of the slot.

Hand operated vacuum pumps as claimed in claim 1 and as herein described.

11 Hand operated vacuum pumps as herein described with reference to the accompanying drawings.

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