Double acting diaphragm pump

Abstract

 A double acting, double diaphragm pump for use in various engineering fields, especially in the fields of drilling and grouting, comprises two large flexible diaphragms (33,56) acting in opposite senses and a low-speed motor (3) together with a transmission system whereby rotational movement of the low-speed motor (3) is converted into longitudinal movement of connecting rods (28,29) of the diaphragms by means of a swing arm (15), so as to enable the flexible diaphragms to draw liquid through one-way inlet valves (39,51) into the pump and push liquid through one-way outlet valves out of the pump.

Description

[0001] THIS INVENTION relates to improvements in or relating to pumps and, in particular, to a liquid pump for use in various engineering fields, especially in the fields of drilling and grouting.

[0002] Various kinds of liquid pumps, including centrifugal pumps, reciprocating pumps, vibrational pumps, screw pumps and gear pumps, etc., are being produced for use at present. Each of the above types of pump has its own advantages and disadvantages in performance. For example, centrifugal pumps throughput a relatively large volume of liquid at a relatively low pressure, but the liquid throughput gets smaller if the pressure is increased.

[0003] In drilling engineering, a pump which is able to throughput a relatively small volume of liquid at a relatively high pressure, such as a reciprocating pump, is preferred when drilling, whilst a pump which throughputs a relatively large volume of liquid (usually a centrifugal pump) is needed when cleaning the hole drilled. After these two stages, a special pump for performing grouting operations may also be necessary. Thus, three sets of power systems and pipe lines must be provided for the three different kinds of pumps, which causes a lot of service and maintenance problems whilst getting a very low efficiency.

[0004] To solve the above problem, a multi-stage centrifugal pump has been proposed which provides a constant volume of liquid at a relatively high pressure but requires more power. However, it is still not suitable for drilling work because it is easily clogged by the sand, mud and rock brought up by the circulating water in operation. Other recently proposed pumps such as multi-­piston reciprocating pumps and screw pumps have made some improvements, but they have not fully met the requirements of drilling work in some respects. In particular, they are too large, require too much power and are uneconomical. For example, a screw pump pumping a liquid volume of 19m³ (5000 US gallons) per hour typically has a length of 4m (12 feet) and requires a power of 15KW (20 HP).

[0005] It is an object of the present invention to enable the provision of a pump for use in drilling, grouting and the like whereby the above disadvantages may be overcome or at least mitigated.

[0006] Accordingly, the invention provides a double acting diaphragm pump, which pump comprises at least one diaphragm, first and second chambers, and means for flexing the or each diaphragm, the arrangement being such that, in use, during a forward stroke the volume of the first chamber is increased and the volume of the second chamber is decreased and, during a return stroke, the volume of the first chamber is decreased and the volume of the second chamber is increased.

[0007] Thus, the invention enables the provision of a pump which is simple in construction and lightweight, provides a large volume of liquid at a high pressure, and requires only a small amount of power when operating with mud, water or even in cement grouting. In processes including drilling, flushing and grouting, only one such pump is required. Thus, the operations of drilling, flushing and grouting can be carried out continuously by using the drill rod for grouting and a much higher efficiency can be achieved.

[0008] For a better understanding of the present invention, and to show how the same may be put into effect, reference will be made, by way of example, to the accompanying drawings, in which:

FIGURE 1 is a front view of a pump in accordance with the invention;

FIGURE 2 is a sectional view of the pump of Figure 1;

FIGURE 3 is a side view of the pump of Figure 1;

FIGURE 4 is a sectional side view of the pump of Figure 1; and

FIGURE 5 is a top plan view of the pump of Figure 1.

[0009] Referring now to the drawings, a pump in accordance with the invention for use in drilling engineering is a double acting, double diaphragm pump comprising two large flexible diaphragms acting in opposite senses and a low-­speed motor of 100 to 120 RPM. The low-speed motor 3 is fixed on a frame 1 by means of four bolts 2 and a casing 5 of the pump is also fixed on the frame 1 by means of four bolts 4. The driving shaft 6 of the motor 3 is engaged by a rotary plate 7 and a flanged shaft 9 is fixed in an eccentric hole of the rotary plate 7 by means of four bolts so that rotation of the driving shaft 6 of the motor 3 can be converted to movement of the flanged shaft 9 about the common axis of the rotary plate 7 and the motor 3. On the part of the flanged shaft 9 extending beyond the rotary plate 7 are mounted two pairs of bearings with a ring 11 of variable length therebetween which makes the total length of the ring and the four bearings equal to that of the extending part of the flanged shaft 9. The bearings 10 are locked axially by means of a cover 12 mounted on the outer end of the flanged shaft 9 by means of three bolts 13 and three spring washers. The extending part, with the bearings, of the flanged shaft 9 slides along an elongate slot of a swing arm 15, the other end of the swing arm 15 being connected to a supporting unit 17 by means of a shaft 16 passing through a hole 18. Three bearings are mounted on the shaft 16, so that the swing arm 15 can swing about the axis of the hole 18 in the supporting unit 17. Below the hole 18, there is a hole 19 in the swing arm 15, through which a shaft 20 is also mounted by means of a set of bearings 21 and a ring 22 so that the swing arm 15 is also connected to a connecting block 23 which has holes 24 and 25 on either side of the hole 19 to link the same to connecting rods 28, 29 by means of shafts 26, 27, respectively.

[0010] The driving mechanism for each diaphragm will now be described by reference to the left hand diaphragm as viewed in Figure 2, although it will be understood that both mechanisms are identical. The outer end of the connecting rod 28, 29 extends through a piston head 30, 31 and is screwed into a piston cover 32. When the piston cover 32 is screwed down, the middle part of the diaphragm 33, 56 is clamped tightly between the piston head and the piston cover by the inner part of the piston cover 34 whilst the periphery of the diaphragm 33, 56 is clamped tightly between a pump cylinder 36 connected to the casing 5 and the pump cover 37 in an internal slot 35 by means of six bolts 38, whereby the pump cylinder 36 is connected to the casing 5. Valve units 40, 39 are mounted on the upper and lower part of the pump cover 37, respectively. The lower valve unit 39 is connected to the pump cover 37 by means of an adaptor 41 whilst the upper valve unit 40 is also connected thereto by means of an adaptor 61. The valve units 39, 40 comprise steel balls 42, 43 and ball seats 44, 45, respectively. The ball seats 44, 45 are similar in construction except that the upper part of one ball seat 45 has three or four small columns of triangular cross-section 46 which limit the movement of the respective steel ball 43. There are no such columns on the other valve seat 44 but two or three columns are disposed on the pump cover to perform a similar function and limit movement of the respective ball 42.

[0011] The pump is generally symmetrical about a centre line as viewed in Figure 2 and a T-shaped inlet pipe 48 has a central port connected to a feed pipe and two other ports connected to the inlet valves 39, 51 of the pump means of flanges 49, 50 respectively. The outlet pipe 52 of the pump is also T-shaped with its centre port linked to the drilling machine or the like in use and its other two ports connected to the outlet valves 40, 55 of the pump by means of flanges 53, 54, respectively.

[0012] The diaphragms 33, 56 have a three layer sandwich structure. The outer two layers are made up of rubber plates of 3 to 6 mm in thickness with a total thickness of 10 to 12 mm, whilst the middle layer comprises resilient sheet metal which imparts stiffness to the diaphragm. The sheet metal surface is lubricated with grease to dissipate the heat from friction.

[0013] When operating the double acting double diaphragm pump, one should first ensure that the machine is on a level surface. Otherwise the steel balls 42, 43 will not be able to seat correctly and thus seal up the valves and this will result in a lower efficiency of the pump. Then, the centre port of the inlet pipe 48 can be joined to a water tank, flushing pond, or the like with a hose, while the centre port of the outlet pipe 52 is joined to the flushing inlet of a rotary head for a drilling machine or the like. As the motor 3 is started (with a clockwise or anticlockwise rotation at 100 to 120 RPM), the motor shaft 6 drives the rotary plate 7 in rotation and the flanged shaft 9 fixed to the plate 7 rotates along the circumference 57. Since the extending part of the flanged shaft 9 can slide in the elongate slot 58 of the swing arm 15, the movement of the flanged shaft 9 causes the swing arm 15 to swing about the axis of the hole 18 at an amplitude of 36°. Because the connecting block 23 is connected to the swing arm 15 through the hole 19, it reciprocates as the swing arm 15 swings.

[0014] As shown in Figure 2, when the swing arm 15 swings to the left, it pushes the diaphragm 33 to the left through the connecting block 23 and the connecting rod 28 whilst the diaphragm unit 56 is also pulled to the left. The pressure generated in the left hand pump space squeezes the liquid out from the pump which presses the steel ball 42 tightly against its seat to seal the lower valve whilst pushing the steel ball 43 away from its seat to open the upper valve and let the liquid flow out to the outlet pipe 52. In the meantime, the back pressure produced in the right hand pump space draws liquid into the pump from the inlet pipe 48, the steel ball 62 being pushed up by the liquid to open the inlet valve 51 and the steel ball 59 being drawn down to close the outlet valve 55. As the swing arm 15 swings to the right, the liquid in the right hand pump space will be pressed into the outlet pipe 52 and the left hand pump space will draw in liquid from the inlet pipe 48. Thus, once the motor 3 is started, liquid will be pumped from the water tank to the drilling machine continuously.

[0015] The length of the left-right stroke of the flexible diaphragms is about 30mm. The liquid pressure generated by the pump can reach 1.4 x 10⁶ Nm^-2 (200 PSl). The liquid volume of the pump can be calculated as follows:
3.2 x 10^-3 m³ (0.85 US gallons) can be transferred per stroke; if the pistons move 100 times per minute (the motor having a speed of 100 RPM), then 0.32 m³ (85 US gallons) can be transferred per minute; therefore, the capacity of the pump is about 19 m³ (5,000 US gallons) per hour.

Claims

1. A double acting diaphragm pump, in particular for use in drilling, grouting and the like, characterized by at least one diaphragm (33, 56), first and second chambers, and flexing means (3,6,7,9,15,28,29) for flexing the or each diaphragm, the arrangement being such that, in use, during a forward stroke the volume of the first chamber is increased and the volume of the second chamber is decreased and, during a return stroke, the volume of the first chamber is decreased and the volume of the second chamber is increased.

2. A pump according to claim 1, characterized by a first diaphragm (33) bounding the first chamber and a second diaphragm (56) bounding the second chamber, the flexing means (3,6,7,9,15,28,29) being arranged to flex both diaphragms (33,56) simultaneously.

3. A pump according to claim 1 or 2, characterized in that the flexing means (3,6,7,9,15,28,29) comprises a motor (3) and pivotable means (9,15) for converting rotation of the motor into longitudinal movement of a part of the or each diaphragm (33,56).

4. A pump according to claim 3, characterized in that a driving shaft (6) of the motor (3) engages a rotary plate (7) carrying an eccentric shaft (9).

5. A pump according to claim 4, characterized in that the pivotable means comprises a swing arm (15), which is pivotable with respect to a casing (5) of the pump, and the eccentric shaft (9) is slidable in an elongate slot (58) in the swing arm.

6. A pump according to claim 5, characterized in that the motor (3) and the casing (5) of the pump are mounted on a frame (1).

7. A pump according to claim 5 or 6, characterized in that a piston rod (28,29) for flexing the or each diaphragm (33,56) is pivotable with respect to the swing arm (15) about a pivot axis (19) which is spaced from and parallel to the pivot axis (18) of the swing arm with respect to the casing (5).

8. A pump according to claim 7, characterized in that or each piston rod (28,29) extends through a piston head (30,31) and is screwed to a piston cover (32), the middle part of the or each diaphragm (33,56) being clamped between the piston head and the piston cover whilst the periphery of the or each diaphragm (33,56) is clamped between an annular member (36) and a cover (37) of the pump.

9. A pump according to claim 8, characterized in that the or each annular member (36) is connected to the casing (5), and valves (39,40) are mounted on the upper and lower parts of the or each pump cover (37).

10. A pump according to claim 9, characterized in that each valve (39,40) is a ball valve comprising a steel ball (42,43) and a valve seat (44,45), the valve seat of the or each upper valve having means for guiding movement of the respective ball and the or each lower valve being provided with means, on the pump cover (37), for guiding movement of the respective ball.

11. A pump according to any one of the preceding claims, characterized in that the or each diaphragm (33,56) has a three layer sandwich structure of which the outer two layers are made up of rubber plates of 3 to 6 mm in thickness with a total thickness of 10 to 12 mm, and the middle layer comprises resilient sheet metal.

12. A pump according to any one of the preceding claims, characterized by a T-shaped inlet pipe (48) having the centre port thereof connected to a feed pipe and one of the other two ports thereof connected to an inlet valve (39) of the first chamber, the other of the other two parts thereof being connected to an inlet valve (51) of the second chamber, and a T-shaped outlet pipe (52) having the centre port thereof connectable to a drilling machine and one of the other two ports thereof connected to an outlet valve of the first chamber, the other of the other two ports thereof being connected to an outlet valve of the second chamber.

Drawing