Axial plunger slurry pump

Details Axial plunger slurry pump Axial plunger slurry pump

1999-07-06

2001-02-13

Thorpe, Timothy S. (Department: 3746)

Pumps

Three or more cylinders arranged in parallel, radial, or...

C417S569000, C264S159000, C092S16500R, C092S057000, C092S251000, C091S37500R, C091S485000, C091S488000, C091S489000, C091S499000, C091S505000, C091S506000, C074S060000, C222S321100

Reexamination Certificate

active

06186747

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a pump adapted for conveying heterogeneous fluids or viscous fluids.
BACKGROUND OF THE INVENTION
Until recently, a three-cylinder piston pump driven by a crank link mechanism is commonly used in oil drillings. This pump may generate a high pressure of 20-25 Mpa as well as a flow rate up to 40 l/sec and is widely used in processes of high pressure jet-drillings, near-equilibrium drillings and directional group drillings, but it is complex in structure, heavy in weight, and difficult in transportation. In addition, the cylinders and pistons of the pump are easily worn and such a pump has a short service life, inefficiency, inconvenience in assembling and disassembling, and a non-uniform output flow. Moreover, the clearance between transmission members, such as a crank and a link, may be increased as the service time is extended and the wear of the members becomes intensified, which will aggravate the impact of movement and add the non-uniformity of the flow. This non-uniformity will cause transfer lines to jump in a drilling process, which gives an impact to well walls and is associated with stronger noises. The Chinese Utility Model No. 85203981 entitled “Slurry Pump for Oil Drilling” proposed a seven-cylinder rotary plunger pump with a plunger moved in a cylinder by a swashplate and a sloping cam plate. In comparison with the aforementioned three-cylinder plunger pump, the seven-cylinder rotary plunger pump has a smaller volume, a light weight, a uniform output flow, and a higher pressure; however, it also suffers from the easily worn plunger and cylinders, a short service life, inconvenience in maintenance, and a violent impact of movement, etc.
SUMMARY OF THE INVENTION
The primary object of the invention is to provide an axial plunger slurry pump having a small volume, a light weight, a uniform output flow, a high efficiency, and a long service life to overcome the disadvantages of the known slurry pumps.
An another object of the invention is to provide an axial plunger slurry pump which has further advantages in convenient assembling and disassembling and easy maintenance.
A further object of the invention is to provide an axial plunger type slurry pump which may automatically compensate the wear clearance between a ball and a ball socket of a ball and socket joint, thereby decreasing the impact of movement and the noise.
A yet another object of the invention is to provide an axial plunger slurry pump which has further a pump valve of a long service life and a reliable seal.
According to the present invention, there is provided an axial plunger slurry pump comprising: a pump body, a sloping cam plate located in the pump body and driven by a drive shaft, a swashplate supported on the drive shaft through a ball and socket joint and swinging as the sloping cam plate rotates, at least seven plungers, each of which is coupled with the swashplate by means of a ball of one of two-ball links and moves reciprocally in a cylinder as the swashplate swings, and a pump head with a pump valve, wherein each of the plunger comprises a plunger body with a rubber piston positioned in its front end and being able to slide over it, and an oil receiving gap communicating with an oil passage disposed between two facing end surfaces of the plunger body and the rubber piston, and wherein there are check valves to keep the oil from reflowing, each of which is provided in an oil passage between a ball of each of two-ball links, which ball is coupled with the swashplate, and the swashplate.
The cylinder and the plunger of the axial plunger slurry pump according to the invention are preferably fitted together by means of a half-and-half locating pad, a cylinder sleeve, a pressing cap, and a locking device which are successively connected with the pump body.
In the axial plunger slurry pump according to the invention, a ball of the ball and socket joint and a support shaft are preferably connected with each other in such a manner that they may slide relative to each other along an axial direction, and the ball is always biased against a ball socket in the swashplate by a bias device.
In an aspect of the invention, the pump valve is preferably provided with a conical valve core which has oblique straight blades at its lower end and is fitted with a valve seat.
More preferably, there are a plurality of reinforcing support stays evenly and circumferentially distributed between the pump body and the pump head.
In the axial plunger slurry pump according to the invention, there is at the front end of the plunger body the rubber which may slide over it, there is the oil receiving gap between the two facing end surfaces of the plunger body and the rubber piston, and there is a check valve to keep the oil from reflowing in each oil passage between a ball of a two-ball link, which ball is coupled with the swashplate, and the swashplate. As a result, in the operation of the pump, during the compression stroke, firstly, there is an equilibrium between an inner pressure in the oil receiving gap and an output pressure because the oil has been sealed in the oil receiving gap, so that the two sides of the rubber piston are in a static pressure equilibrium state, thereby improving the operation conditions of it and causing it to serve the only function of separating slurry. Moreover, because the rubber piston is in equilibrium, dirty materials in the pumped slurry are difficult to wedge into the interface of the rubber piston and the cylinder thereby reducing the wear of the rubber piston and the cylinder. Secondly, because an oil pressure at the ball of the two-ball link, which ball is coupled with the swashplate, is in equilibrium with an oil pressure at the plunger body, the two-ball link is also in a static pressure equilibrium sate, thereby improving the force receiving conditions of an plunger assembly and prolonging the service life thereof.
Moreover, in the axial plunger slurry pump according to the invention, each of the cylinders and the pump body are fitted together by means of the half-and-half locating pad, the cylinder sleeve, the pressing cap, and the locking device which are successively connected with the pump body; therefore, when the rubber piston or the cylinder are worn out, only by unscrewing the pressing cap, pulling out the half-and-half locating pad from two sides, and then withdrawing the plunger assembly into the pump body, one can remove the cylinder laterally to repair it or the plunger. Thus, the maintenance and assembling-disassembling can be easily carried out.
Furthermore, in the axial plunger slurry pump according to the invention, because the ball of the ball and socket joint and the support shaft are so designed that they may slide relative to each other, and that the ball is biased against the ball socket in the swashplate by the bias device provided between the ball and a pump cover, it is possible to compensate automatically the wear clearance between the ball and the ball socket and to decrease the impact of movement. Thus the pump may operate more smoothly with a lower noise.
In the axial plunger slurry pump according to the invention, there are provided with oblique straight blades at the lower end of the valve core of the pump valve. Thus, in operation, the liquid flow and the oblique blades interact so that the blades rotate thereby rotating the valve core. In this way, the quantity of particle materials remaining on the valve seat decreases significantly, so that a more reliable sealing of the conical surfaces of the valve core and valve seat is realized. Meanwhile, because the rotation of the valve core will pulverize the particles detained on the surfaces of the valve core and the valve seat, the sealing of the conical surfaces is ensured. In addition, the continuous rotating of the valve core may compensate the wear on the contacting portions of the conical surfaces, which will prolong the service life of the pump and further improve the efficiency of the pump.
Moreover, the axial plunger slurry pump according to the invent

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