GB1571459A

GB1571459A - Vacuum pumps and vacuum pump assemblies

Info

Publication number: GB1571459A
Application number: GB53014/77A
Authority: GB
Original assignee: INSTAVAC Ltd
Current assignee: INSTAVAC Ltd
Priority date: 1977-12-20
Filing date: 1977-12-20
Publication date: 1980-07-16

Description

(54) VACUUM PUMPS AND VACUUM PUMP ASSEMBLIES (71) We, INSTAVAC LIMITED formerly HERMAC FABRICATIONS LI MITED, a British Company of Jute Lane, Brimsdown, Enfield, Middlesex EN3 7PJ, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to vacuum pumps and to vacuum pump assemblies.

It is often necessary in the medical and other fields to provide a manually operable vacuum pump. In the medical field. for example, such a pump is often used as a stomach pump and can be used for other operations of this type. There are two main types of pump of this nature. firstly. an electrically operated pump. which may either be mains operated or battery operated and which is relatively bulky and expensive to manufacture. Secondly a foot pump has been provided which is usually in the form of a conventional automobile foot pump. but with a piston-washer arranged the other way round, so that it produces suction rather than pressure. Such an assembly is both bulky and heavy. It is also not very aesthetically pleasing.

According to the present invention. there is provided a vacuum pump comprising a cylinder, a piston in the cylinder. a piston rod for moving the piston between a first, rest position in which one end of the piston lies adjacent to a section of the cylinder having both an inlet port and an outlet port the inlet port and outlet port each having an associated one-wav valve, and a second extreme position in which the opposite end of the piston lies adjacent to a vent port in the wall of the cylinder the vent port being at one end of the cylinder and the piston rod extending through the other end of the cylinder and means to return the piston to its rest position.

It is advantageous for the piston to be returned by spring pressure, and if the spring pressure is sufficient, in ordinary pumps, to compress the gas on the inlet port side of the piston, then it will be extremely difficult to operate the pump by foot, unless some considerable mechanical advantage is provided. This is done in the automobile pump by having a long lever which operates the piston and at the same time compresses the spring.

This, as indicated, provides a bulky arrangement.

On the other hand, with the construction of the present invention, by providing the output port, on the inlet port side of the piston, when the piston is returned by spring pressure, any air behind the piston during this motion will be allowed to escape through the outlet port. The inlet valve will, of course, close while this takes place. With such an arrangement it is possible to have a compression spring for which the spring force is relatively small, because it does not have to do a very large amount of work, but merely to move the piston itself and any operating member therewith.

In a preferred construction embodying the invention, the cylinder is mounted vertically, and the piston rod extends upwardly through the upper end wall of the cylinder and is operated by foot pressure thereon.

The upper end of the operating member may simply be a circular disc, for example, with a non-slip upper surface.

The inlet valve and the outlet valve are preferably both located in the end wall of the cylinder, advantageously at the upper end thereof when the cylinder axis is vertical, the vent port of the cylinder being provided at the bottom, and a suitable dirt trap, for example, in the form of a wire gauze or mesh, may cover the vent port to prevent dirt being drawn into the cylinder.

The invention also contemplates a vacuum pump assembly comprising a base plate at least one vacuum bottle having an inlet and outlet duct. and a vacuum pump according to the present invention mounted on the base, the outlet port of the vacuum bottle being connected to the inlet port of the pump.

ln order that the present invention may more readily be understood, the following description is given, noerely by way of example, reference being made to the accclmpanvin drawing. in which the sole Figure is;; crc,ss-scction through one embo dhllellt of vactiuni pump assembly according to the invention.

Referring '10', to the driwing, there is illustrated therein. a pump assembly embodying the present invention including a base plate 1() having mounted thereon bv means of suitable support arrangement (not shown) two vacuum bottles 12 and 14.

Also mounted on the base plate 10 is a cylinder I 16 having reciprocable therein a piston 1S which is associated with an operat inp member comprising a piston rod 20 having a pedal 22 at its top end. the upper surface of the pedal 22 being provided with a non-slip surface, such as a rubber disc.

The piston is urged upwardly within the cylinder 16 by means of a coil compression spring 24 which engages on the base plate at the foot. Centrally of the cylinder in the base plate is a vent port 26 and a dirt trap wire mesh 28 engages over the vent port.

At its upper end. the cylinder has an end plate 30. through which the operating memher 20 passes. An inlet port 32 is provided with a Shrader ( Registered Trade Mark) valve '4. from which the spring has been removed.

Also formed in the top plate 32 is outlet port 3(l which has mounted therein a nonreturn valve member in the form of a ball 38.

The valve 34. has, associated therewith, an inlet pipe connection 40 over which is fitted a flexible rubber hose 42 which connects to an outlet port 44 of the first vacuum bottle 14. An inlet port 46 is provided on the first bottle 12 and a connecting line 50 connects two further ports IS and 49 of the two vacuum bottles 14 and 1' respectively.

In operation. the user places the thusformed assembly on the ground and connects the inlet duct 46 of the vacuum bottle to a suitable device. such as a stomach pump probe. The user then places his foot on the plates 22 and pushes downwardly. thus compressing the spring 24. Air is thus pushed out of the vent port 26 and further air is drawn in past the valve 34 and through the inlet port 32.

When the piston reaches the bottom of its stroke. it is released and the spring 24 forces the piston upwardly. The valve 34 immediately closes and the valve 38 opens thus allowing air above the piston 18 to escape.

It will be appreciated that by providing the outlet port 36 and the non-return valve 38, the return force of the spring 24 need not be partictilarly high, because it is only necessary for the spring to force the piston upwardly and it issnot necessary for it to do any work in compressing the air above the piston. It will be understood that during the downward slroke, the valve 38 closes, and the valve 34 opens so that air can be drawn into the cylinder.

The illustrited construction is very compact since the piston and cylinder arrange ment can be mounted vertically and it is not necessary to provide any conventional lever mechanism to compress a powerful spring which will be necessary if the port 36 and its valve 38 were not provided. This has not only the advanttge of making the assembly more compact, hut it also makes it very much lighter. If the assembly is used as a portable vacuum source, eg., for use in an ambulance, boat or the like, then it is very compact and very light.

While the construction of the present invention has been designed primarily for use as a medical vacuum pump, it is also contemplated that it could be used for other purposes, such as for a bilge pump with, of course, the bilge water being sucked into, and retained in the vacuum bottles. While two bottles 12, 14 have been indicated to act as vacuum bottles which will receive material evacuated. one or more bottles can be provided and they may be made any suitable size for a particular requirement.

WHAT WE CLAIM IS: 1. A vacuum pump comprising a cylinder, a piston in the cylinder, a piston rod for moving the piston between a first, rest position in which one end of the piston lies adjacent to a section of the cylinder having both an inlet port and an outlet port the inlet port and the outlet port each having an associated one-way valve, and a second extreme position in which the opposite end of the piston lies adjacent to a vent port in the wall of the cylinder, the vent port being at one end of the cylinder and the piston rod extending through the other end of the cylinder and means to return the piston to its rest position.

2. A pump according to Claim 1, wherein the return means for the piston comprises a compression spring located within the cylinder.

3. A pump according to Claim 2, wherein the return spring contacts said opposite end of the piston.

4. A pump according to Claims 1, 2 or 3 wherein said inlet one-way valve is one which is not spring-urged to its closed

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. vacuum pump assembly comprising a base plate at least one vacuum bottle having an inlet and outlet duct. and a vacuum pump according to the present invention mounted on the base, the outlet port of the vacuum bottle being connected to the inlet port of the pump. ln order that the present invention may more readily be understood, the following description is given, noerely by way of example, reference being made to the accclmpanvin drawing. in which the sole Figure is;; crc,ss-scction through one embo dhllellt of vactiuni pump assembly according to the invention. Referring '10', to the driwing, there is illustrated therein. a pump assembly embodying the present invention including a base plate 1() having mounted thereon bv means of suitable support arrangement (not shown) two vacuum bottles 12 and 14. Also mounted on the base plate 10 is a cylinder I 16 having reciprocable therein a piston 1S which is associated with an operat inp member comprising a piston rod 20 having a pedal 22 at its top end. the upper surface of the pedal 22 being provided with a non-slip surface, such as a rubber disc. The piston is urged upwardly within the cylinder 16 by means of a coil compression spring 24 which engages on the base plate at the foot. Centrally of the cylinder in the base plate is a vent port 26 and a dirt trap wire mesh 28 engages over the vent port. At its upper end. the cylinder has an end plate 30. through which the operating memher 20 passes. An inlet port 32 is provided with a Shrader ( Registered Trade Mark) valve '4. from which the spring has been removed. Also formed in the top plate 32 is outlet port 3(l which has mounted therein a nonreturn valve member in the form of a ball 38. The valve 34. has, associated therewith, an inlet pipe connection 40 over which is fitted a flexible rubber hose 42 which connects to an outlet port 44 of the first vacuum bottle 14. An inlet port 46 is provided on the first bottle 12 and a connecting line 50 connects two further ports IS and 49 of the two vacuum bottles 14 and 1' respectively. In operation. the user places the thusformed assembly on the ground and connects the inlet duct 46 of the vacuum bottle to a suitable device. such as a stomach pump probe. The user then places his foot on the plates 22 and pushes downwardly. thus compressing the spring 24. Air is thus pushed out of the vent port 26 and further air is drawn in past the valve 34 and through the inlet port 32. When the piston reaches the bottom of its stroke. it is released and the spring 24 forces the piston upwardly. The valve 34 immediately closes and the valve 38 opens thus allowing air above the piston 18 to escape. It will be appreciated that by providing the outlet port 36 and the non-return valve 38, the return force of the spring 24 need not be partictilarly high, because it is only necessary for the spring to force the piston upwardly and it issnot necessary for it to do any work in compressing the air above the piston. It will be understood that during the downward slroke, the valve 38 closes, and the valve 34 opens so that air can be drawn into the cylinder. The illustrited construction is very compact since the piston and cylinder arrange ment can be mounted vertically and it is not necessary to provide any conventional lever mechanism to compress a powerful spring which will be necessary if the port 36 and its valve 38 were not provided. This has not only the advanttge of making the assembly more compact, hut it also makes it very much lighter. If the assembly is used as a portable vacuum source, eg., for use in an ambulance, boat or the like, then it is very compact and very light. While the construction of the present invention has been designed primarily for use as a medical vacuum pump, it is also contemplated that it could be used for other purposes, such as for a bilge pump with, of course, the bilge water being sucked into, and retained in the vacuum bottles. While two bottles 12, 14 have been indicated to act as vacuum bottles which will receive material evacuated. one or more bottles can be provided and they may be made any suitable size for a particular requirement. WHAT WE CLAIM IS:

1. A vacuum pump comprising a cylinder, a piston in the cylinder, a piston rod for moving the piston between a first, rest position in which one end of the piston lies adjacent to a section of the cylinder having both an inlet port and an outlet port the inlet port and the outlet port each having an associated one-way valve, and a second extreme position in which the opposite end of the piston lies adjacent to a vent port in the wall of the cylinder, the vent port being at one end of the cylinder and the piston rod extending through the other end of the cylinder and means to return the piston to its rest position.

position.

5. A pump according to any one of the preceding claims, wherein said inlet valve is located in the end wall of the cylinder at its other end.

6. A pump according to any one of the preceding claims, wherein the outlet port is located in the end wall of the cylinder at its other end.

7. A pump according to any one of the preceding claims. wherein the pump is mounted with the cylinder axis vertical, and the piston rod extends upwardly through the upper end of the cylinder and can be operated by foot pressure thereon.

8. A pump according to claim 7, wherein the vent port is located in the bottom of the cvlinder and has a dirt trap, eg., a wire mesh thereon.

9. A vacuum pump substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.

10. A vacuum pump assembly comprising a base plate, at least one vacuum bottle thereon having inlet and outlet ducts thereon. a vacuum pump according to any one of the preceding claims mounted on said plate.

the outlet duct of the vacuum vessel being connected to the inlet port of the vacuum pump.

11. A vacuum pump assembly substantiallv as hereinbefore described with reference to and as illustrated in the accompany ing drawings.