PISTON PUMP

Abstract: One and the same drive gear (6) is associated with two adjacent pump cylinders (3, 4). Each pump cylinder has a separate valve unit (1, 2). The two pump cylinders (3, 4) have a common piston rod (15) having a pump piston (16, 17) at each end. The piston rod is made in the form of a toothed rack (15), the drive gear (5) comprising motor-driven gearwheels (11-14) in engaging interaction with the toothed rack (15).

Description: PISTON PUMP The present invention relates to a piston pump as disclosed in the preamble of claim 1 The invention has been especially developed as a drilling fluid pump The standard drilling fluid pumps are connecting rod operated piston pumps These are relatively heavy structures, and their service life is also comparatively short Therefore there is a need for a new type of drilling fluid pump that is lighter in weight and has a longer service life This need is met by means of a piston pump as disclosed in claim 1 Additional features of the invention are disclosed in the dependent claims, and advantages of the invention will be explained in detail in the following description of an exemplary embodiment with reference to the drawings, wherein Figure 1 is a perspective view of a drilling fluid pump according to the invention, Figure 2 is a side view of the pump in Figure 1 , Figure 3 is a sectional view taken along the line A-A in Figure 2, Figure 4 is a sectional view taken along the line B-B in Figure 2, and Figure 5 is a perspective view of an embodiment in which two pumps are placed on a frame The drilling fluid pump shown in Figure 1 comprises two valve units 1 and 2, two pump cylinders 3 and 4, and a central drive unit 5 The valve units 1 and 2 are as known from the conventional pumps, and the pump cylinders 3 and 4 are also conventional Therefore these components are not described in any more detail here The central drive unit comprises a housing 6 and two electric drive motors 7 and 8 mounted thereon The two drive motors 7 and 8 are via gearboxes 9, 10 and gearwheels 11 - 14 drive-connected to a toothed rack 15 which moves in the two pump cylinders 3, 4 At each end, the toothed rack 15 has a piston 16 and 17 respectively which act as pump pistons in their respective cylinder 3, 4. The toothed rack 15 has an H-shaped cross-section, see Figure 4. The pump shown in Figure 1 is symmetric, i.e., the two valve units 1, 2 and the pump cylinders 3, 4 are identical to one another. When the pump is in operation, the toothed rack 15 is moved back and forth by the electric motors 7, 8 via the gearboxes 9, 10 and the gearwheels 13 - 14. The pistons will then draw in and force out drilling fluid through the associated valve unit 1, 2. The new drilling fluid pump can be made having a weight that is about four times lighter than the conventional drilling fluid pumps which have heavy drive gears. The reduction in weight will depend on the length of the cylinders. An expedient pump cylinder length is 3 metres, which is about six times longer than in a conventional pump. The piston velocity can then be the same as in a conventional pump, and the pump cylinder diameter can be as in the known pumps, for example as much as 6" in cylinder diameter. A service life is thus obtained for the inventive pump that is six times longer than that of the conventional pumps. Figure 5 shows a drilling fluid pump which differs from that in Figure 1 only in that it has been "doubled", and where the pumps are placed on a transport or support frame 18.

Claims: P a t e n t c l a i m s 1. A piston pump comprising a pump cylinder (3, 4) having a first and second end, a valve 5 unit (1, 2) in the first end of the pump cylinder (3, 4), a pump piston (16, 17) in the pump cylinder (3, 4), a piston rod (15) that passes into the pump cylinder (3, 4) at the second end thereof and is connected to the pump piston (16, 17), and a drive gear (5) that is drive-connected to the piston rod (15) for reciprocating motion o thereof in the pump cylinder (3, 4), characterised in that one and the same drive gear is associated with two adjacent pump cylinders (3, 4) which each have a separate valve unit (1, 2), that the two pump cylinders (3, 4) have a common piston rod (15) with a pump piston (16, 17) at each end, and that the piston rod is made in the form of a toothed rack (15), s the drive gear (5) comprising motor-driven gearwheels (11 - 14) in engaging interaction with the toothed rack (15). 2. A piston pump according to claim 1, characterised in that the toothed rack (15) has teeth o on two opposite sides and has engaging interaction with two gearwheels (11 - 14) on each of these opposite sides. 3. A piston pump according to claim 2, characterised in that pairs of adjacent gearwheels 5 (11 - 14) are drive-connected to a respective drive motor (1, 8). 4. A piston pump according to claims 1-3, characterised in that the toothed rack is made in the form of a H-beam.

Inventors: EILERTSEN BJOERN, EILERTSEN, BJOERN
Applicants: EILERTSEN BJOERN, ENG & DRILLING MACHINERY AS, EILERTSEN, BJOERN, ENGINEERING & DRILLING MACHINERY AS
Application year: 2000
Main classification: F04B9
IPC codes: F04B9