GB1574898A

GB1574898A - Pumping apparatus

Info

Publication number: GB1574898A
Application number: GB23595/78A
Authority: GB
Original assignee: Draegerwerk AG and Co KGaA
Current assignee: Draegerwerk AG and Co KGaA
Priority date: 1977-06-14
Filing date: 1978-05-26
Publication date: 1980-09-10
Also published as: DE2726674B1; FR2394694B1; SU710528A3; FR2394694A1; PL112091B1; PL207572A1; DE2726674C2

Description

(54) PUMPING APPARATUS (71) We, DRAGERWERK AKTIENGESELLSCHAFT, a German company, of Moislinger-Allee 53/55, 2400 Lübeck, Germany, 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:- This invention relates to a pumping apparatus comprising a housing provided with two compartments; two membranes one in each compartment, dividing each compartment into a drive chamber and a pump chamber; a connecting member connected to the membranes for ensuring that, in use, the membranes move together in the same direction; and a control valve having a valve member movable between a first position in which a driving gas may be passed to the drive chamber of one compartment and a second position in which a driving gas may be passed to the drive chamber of the other compartment.

It is desirable that the control valve be switched over only when one pump chamber is substantially completely full and the other pump chamber is substantially completely empty, and vice versa. Also it is preferable for the control valve to be switched over as rapidly as possible from one of said first and second positions to the other of said first and second positions.

According to the present invention there is provided a pumping apparatus comprising a housing provided with two compartments; two membranes one in each compartment, dividing each compartment into a drive chamber and a pump chamber; a connecting member connected to the two membranes for ensuring that in use the membranes move together in the same direction; a control valve having a valve member movable between a first position in which a driving gas may be passed to the drive chamber of one compartment and a second position in which a driving gas may be passed to the drive chamber of the other compartment; an elongate resiliently flexible arm which mechanically connects the connecting member to the control valve member; and means tending to detain a control valve member in the first and second positions; the arrangement being such that, in use, driving gas is supplied via the control valve to one driving chamber to cause the membrane adjacent that driving chamber to move, thereby causing movement of the connecting member, and after such movement over a predetermined flexure of the elongate resiliently flexible arm causes the control valve member to switch over from one of the first and second positions to the other of those positions, so as to cause the driving gas to be supplied to the other driving chamber, thereby reversing the movement of the membranes in their compartments.

Preferably the valve member is a piston slidably located in a bore in the housing with the axis of the piston parallel to the axis of the connecting member.

Preferably the means for tending to detain the piston in the first and second positions comprises spring loaded balls tending to be urged by the springs into recesses in the piston.

The transfer of the movement of the rigid connecting member and, with it the position of the membranes takes place by means of only one structural unit on the valve member. The tolerances of the elongate resiliently flexible arm are easily checked and keeping the elongate resiliently flexible arm within the desired limits should not present any special problems. By keeping the elongate resiliently flexible arm within these desired limits, the retaining action of the spring loaded balls of the preferred embodiment should be overcome when the membranes have reached a desired switching position. Also the valve member (e.g. the piston) should travel rapidly from position to the other. As the mechanical connection between the connecting member and the valve member, i.e. the elongate resiliently flexible arm, is not too long, the control valve can be arranged inside the housing.This enables a total coolant supply system to be compact and this might be of advantage in a protective suit for example.

Advantageously both pump chambers communicate via non-return valves to an inlet and an outlet for a fluid, the non-return valves which connect the inlet to the pump chambers only permitting fluid to flow from the inlet to the pump chambers and the nonreturn valves which connect the pump chambers to the outlet only permitting fluid to flow from the pump chambers to the outlet.

The elongate resiliently flexible arm may be of circular cross-section or it may be a flat strip of oblong rectangular crosssection.

Conveniently the elongate resiliently flexible arm engages in a lateral recess in the connecting member and in the recess in the piston, and an intermediate portion of the elongate resiliently flexible arm passes through an opening in the rib of the housing whereby in use the elongate resiliently flexible arm oscillates about the centre of the opening.

For a better understanding of the present invention and to show more clearly how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 shows an axial section, along the line 1-I of Figure 2, of a double membrane pumping apparatus according to the present invention; and Figure 2 shows an axial section along the line 11-Il of Figure 1.

The pumping apparatus includes, in a housing 1 two membrane pumps 2, 3 and a control valve 10. The membrane pumps 2, 3 are connected to each other by a rigid connecting member 20 which is mechanically connected to the control valve 10 by an elongate resiliently flexible arm in the form of a bar spring 11. The compartments of the membrane pumps 2, 3 are divided by respective membranes 4, 5 into drive chambers 6, 7 and pump chambers 8, 9. The fluid to be pumped, in this case coolant, is pumped through the pump chambers 8, 9. An inlet 13 for the coolant communicates via non-return valves 14 and 15 (as shown in Figure 2) with the pump chambers 8 and 9 respectively. The non-return valves 14 and 15 permit fluid flow only from the inlet 13 to the pump chambers 8 and 9 respectively. The flow direction at the inlet 13 is indicated by the arrow 12.The pump chambers 8 and 9 communicate via further non-return valves 16 and 17 respectively with an outlet 18, the non-return valves 16 and 17 permitting the fluid to flow only from the pump chambers 8 and 9 respectively to the outlet 18. The flow direction at the outlet 18 is indicated by the arrow 19.

The two membranes 4 and 5 are connected by a rigid connecting member 20.

The membranes 4 and 5 together with the rigid connecting member 20 can reciprocate between two end positions 21 and 22; the pumps 2, 3 are shown at the end position 21 in the Figures, and the other end position 22 is indicated in outline in Figure 1. The housing 1 is provided with an inlet 27 through which driving gas is supplied to the control valve 10 which includes a reciprocable piston 23; an axial bore 28 runs the full length of the piston 23, and the piston 23 is slidingly located in a cylindrical bore 24 of the housing 1. The piston 23 is also provided with two cross bores 29 and 38. The piston 23 can be detailed in two end positions by spring loaded balls 25 and 26 which engage with the recesses in the piston 23. In Figure 1 the piston is shown retained in the right-hand end position by the ball stop 25.In the position shown in Figure 1 the driving gas is supplied to the inlet 27 and flows through the bore 28, cross bore 29 and a bore 30 to the drive chamber 6. At the same time the other drive chamber 7 communicates with the atmosphere via a vertical bore 31, an annular groove 32 around the piston 23 and a further vertical bore 33. Thus the membrane 5 can move across to the right without pressure building up in the drive chamber 7. The bar spring 11 engages with a lateral recess 34 in the connecting member 20 and with another recess 35 in the piston 23. The bar spring 11 also passes through an opening 36 in a rib 37 of the housing and oscillates about the centre of the opening 36.When the piston is in the left-hand end position, the ball stop 26 engages in a recess in the piston 23; the driving gas is then supplied via the other cross bore 38 in the piston 23 and a bore 39 in the housing to the drive chamber 7; and the drive chamber 6 communicates with the atmosphere via vertical bores 40 and 41 in the right-hand side of the housing, which are symmetrical with the bores 31 and 33, and an annular groove near the right-hand end of piston 23.

Figure 1 shows the apparatus at the start of the movement of the membranes 4 and 5 from the first end position 21 to the second end position 22. The drive gas is supplied to the chamber 6 forcing the membranes 4 and 5 across to the right and, consequently forcing the coolant out of the pump chamber 8 and drawing more coolant into the pump chamber 9. As the connecting member 20 moves across with the membranes 4 and 5, the bar spring 11 is flexed and the force of the bar spring 11 on the piston 23, urging the piston to the left, increases. As the membranes 4 and 5 and the connecting member 20 reach the second end position, the force on the piston 23 due to the bar spring 11 exceeds the detaining force due to the ball stop 25. Consequently, the piston 23 disengages from the ball stop 25 and moves rapidly to left until it engages the ball stop 26.The drive gas is now supplied to the drive chamber 7 causing the membranes 4 and 5 to move to the left so that coolant is drawn into the pump chamber 8 and forced out of the pump chamber 9. Again, as the connecting member 20 moves with the membranes 4 and 5 from the second end position 22 to the first end position 21, the bar spring 11 is progressively flexed until the first end position 21 is reached, when the piston 23 is forced across to the right. The apparatus has now returned to the position shown in Figure 1, the first end position 21, ready for the start of another stroke.

The operation of the piston 23 by the bar spring 11 ensured that, at the end of each working stroke, the piston 23 is moved rapidly across from one end position to the other. The bar spring 11 is also suitably dimensioned so as to ensure that each stroke is completed before the piston is switched across.

WHAT WE CLAIM IS: 1. A pumping apparatus comprising a housing provided with two compartments; two membranes one in each compartment, dividing each compartment into a drive chamber and a pump chamber; a connecting member connected to the two membranes for ensuring that in use the membranes move together in the same direction; a control valve having a valve member movable between a first position in which a driving gas may be passed to the drive chamber of one compartment and a second position in which a driving gas may be passed to the drive chamber of the other compartment; an elongate resiliently flexible arm which mechanically connects the connecting member to the control valve member; and means tending to detain the control valve member in the first and second positions; the arrangement being such that, in use, driving gas is supplied via the control valve to one driving chamber to cause the membrane adjacent that driving chamber to move, thereby causing movement of the connecting member, and after such movement over a predetermined flexure of the elongate resiliently flexible arm causes the control valve member to switch from one of the first and second positions to the other of those positions, so as to cause the driving gas to be supplied to the other driving chamber, thereby reversing movement of the membranes in their compartments.

2. A pumping apparatus as claimed in Claim 1, wherein the valve member is a piston slidably located in a bore in the housing.

3. A pumping apparatus as claimed in Claim 2, wherein the axis of the piston is parallel to the axis of the connecting member.

4. A pumping apparatus as claimed in Claim 2 or 3, wherein the means for tending to detain the piston in the first and second positions comprises spring loaded balls tending to be urged by the springs into the recesses in the piston.

5. A pumping apparatus as claimed in any preceding claim, wherein both pump chambers communicate via non-return valves to an inlet and an outlet for a fluid, the non-return valves which connect the inlet to the pump chambers only permitting fluid to flow from the inlet to the pump chambers, and the non-return valves which connect the pump chambers to the outlet only permitting fluid to flow from the pump chambers to the outlet.

6. A pumping apparatus as claimed in any preceding claim, wherein the elongate resiliently flexible arm is of circular crosssection.

7. A pumping apparatus as claimed in any one of Claims 1 to 5, wherein the elongate resiliently flexible arm is a flat strip of oblong rectangular cross-section.

8. A pumping apparatus as claimed in Claim 2, 3 or 4 or in any one of Claims 5 to 7 when appendant to Claim 2, wherein the elongate resilient flexible arm engages in a lateral recess in the connecting member and in a recess in the piston, and wherein an intermediate portion of the elongate resiliently flexible arm passes through an opening in a rib of the housing whereby in use the elongate resiliently flexible arm oscillates about the centre of the opening.

9. A pumping apparatus substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the connecting member 20 reach the second end position, the force on the piston 23 due to the bar spring 11 exceeds the detaining force due to the ball stop 25. Consequently, the piston 23 disengages from the ball stop 25 and moves rapidly to left until it engages the ball stop 26. The drive gas is now supplied to the drive chamber 7 causing the membranes 4 and 5 to move to the left so that coolant is drawn into the pump chamber 8 and forced out of the pump chamber 9. Again, as the connecting member 20 moves with the membranes 4 and 5 from the second end position 22 to the first end position 21, the bar spring 11 is progressively flexed until the first end position 21 is reached, when the piston 23 is forced across to the right.The apparatus has now returned to the position shown in Figure 1, the first end position 21, ready for the start of another stroke. The operation of the piston 23 by the bar spring 11 ensured that, at the end of each working stroke, the piston 23 is moved rapidly across from one end position to the other. The bar spring 11 is also suitably dimensioned so as to ensure that each stroke is completed before the piston is switched across. WHAT WE CLAIM IS:

1. A pumping apparatus comprising a housing provided with two compartments; two membranes one in each compartment, dividing each compartment into a drive chamber and a pump chamber; a connecting member connected to the two membranes for ensuring that in use the membranes move together in the same direction; a control valve having a valve member movable between a first position in which a driving gas may be passed to the drive chamber of one compartment and a second position in which a driving gas may be passed to the drive chamber of the other compartment; an elongate resiliently flexible arm which mechanically connects the connecting member to the control valve member; and means tending to detain the control valve member in the first and second positions; the arrangement being such that, in use, driving gas is supplied via the control valve to one driving chamber to cause the membrane adjacent that driving chamber to move, thereby causing movement of the connecting member, and after such movement over a predetermined flexure of the elongate resiliently flexible arm causes the control valve member to switch from one of the first and second positions to the other of those positions, so as to cause the driving gas to be supplied to the other driving chamber, thereby reversing movement of the membranes in their compartments.