[0001] The present invention relates to a fluid pump which advantageously can be used for
pumping a variety of fluids.
[0002] Simple and cheap prior art pumps comprise a cylinder in which a piston is movable
to accomplish the pumping. Such pumps have the drawback of requiring a high quality
intemal surface in the cylinder. Furthermore, a seal is needed between the piston
and the cylinder. Such a seal causes friction and wear. Regular maintenance is therefore
required. To move the piston in the cylinder a rod, capable of taking loads in both
directions, is needed. This is a substantial drawback if the pump is to be used in
a deep well. The drawback with the piston and cylinder arrangement becomes even more
evident if a fluid containing abrasive material, e.g. cement, is to be pumped.
[0003] The present invention, which is defined in the appended claims, aims at doing away
with the above mentioned drawbacks by replacing the piston with a tubular pump element
of an elastic material having helically extending threads embedded. The elastic material
could advantageously be rubber. The reinforcing threads should be resistant against
deformation and be positioned with a separation that gives a good elasticity to the
tubular pump element.
[0004] The invention is exemplified below with reference to the accompanying drawings in
which fig 1 shows a section through a fluid pump according to the invention. Fig 2
shows a part section through a pump element used in the invention. Fig 3 shows a modified
embodiment of the invention.
[0005] The fluid pressure pump shown in the drawings comprises a housing 11 covered by a
cover 12. An inlet valve 16 is arranged in a channel 14,
15 in the bottom of the housing. The valve element is mounted by means of a screw 13.
Fluid to be pumped is entered into pump chamber 20 through the inlet valve and is
then delivered through outlet valve 18 to a conduit 19 which leads to a delivery point.
Valve element 18 is arranged in channel 17 in the cover
12 and held in place by conduit 19 which is screwed into cover 12. A pump element comprising
a tubular member 21 and end pieces 22,23 is mounted in pump chamber 20. End piece
23 is fixed, e.g. by a wire 24, to cover 12. End piece 22 is elastically connected
to housing 11 by means of an adjustable spring 25. The interior of the tubular member
21 is by means of a conduit 26 connected to a fluid pressure source 32, which is made
in the same way as the pump element 21. The fluid pressure source 32 is connected
to a stand 31 having a lever 34 which in a suitable way, e.g. by means of a wire 33,
makes it possible to change the length of the fluid pressure source. This results
in a change in the fluid pressure, as described below. This change in pressure results
in a change of volume of the pump element 21. This change in volume, caused by moving
lever 3
4 up and down, accomplishes the pumping.
[0006] The tubular member 21, the same is valid for tubular member 32, comprises a tube
41 in which reinforcing threads 42 are embedded. Threads 42 extend helically along
the tube at a pitch angle v. The threads extend in both directions. If the angle v
is greater than anxot(sqrt(2)), approx. 3
5.3° a decrease in the length of the tubular member caused by pressurization of the
interior of the tubular member results in an increase of the volume of the tubular
member. If on the other hand angle v is smaller than the above mentioned value a decrease
in length results in a decrease in volume.
[0007] Adjustment of the force of spring 25 changes the pressure needed from fluid pressure
source 32 to accomplish pumping. In this way it is possible to adjust the pump for
pumping with different counterpressures in conduit 19.
[0008] In the embodiment of the invention shown in fig 3 parts having the same reference
numerals as parts in the fig 1 embodiment function in the same way. In the fig 3 embodiment
the tube 41 has been extended to be clamped to housing 11 and cover 12 by means of
clamps 51 and 52 respectively. The length of the tube 41 has been chosen such that
a predetermined tensile force prevails in the tube. In this way the tube replaces
the spring 25 of fig
1 . However, the pump will then be adapted to a particular counterpressure. In order
to be adapted to another counterpressure the length of the tube of that pump has to
be changed. Tube 41 is provided with a dividing piece 53 clamped to the tube by means
of a clamp 54. Channel 15 communicates with pump chamber 20 via channel 55, groove
56 and hole 57 through tube 41 and clamp 54. The space above dividing piece 53 is
via conduit 26 connected to a fluid pressure source of variable pressure which effects
the pumping.
1. A fluid pump comprising a housing (11) provided with a pump chamber (20), an inlet
valve (16) through which fluid is entered into the pump chamber, an outlet valve (18)
through which fluid is delivered from the pump chamber and a pump element (21) to
vary the volume of the pump chamber, characterized in that the pump element comprises
a tubular member (21) which is made of an elastic material (41) in which reinforcing
threads (42) are embedded, said threads extending helically along the tubular member,
that one of the ends (23) of the tubular member is fixed relative to the housing and
the other end (22) is elastically connected to the housing, and that the interior
of the tubular member is connected to a fluid pressure source (32) of variable pressure.
2. A fluid pump according to claim 1 characterized in that the elastic connection
is obtained by means of a spring (25) the spring force of which is adjustable.
