GB1585794A - Reciprocating pumps - Google Patents

Description

(54) IMPROVEMENTS RELATING TO RECIPROCATING PUMPS (71) We, DAVID JOHN RELF, of 41 Highfield Avenue, Aldershot,- Hampshire and BRUCE JOHN BUCKNER of 3, Windsor Close, High Ridge, Alton, Hampshire, both British Subjects, 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 reciprocating pump suitable for the transport of viscous, pulpy or plastic material, for example coal and admixture such as a pumpability agent which agent fills the voids between individual pieces of coal and facilitates its flow along a pipe or the like.

The invention concerns pumps of the type comprising two pumping cylinders each containing a piston and each alternately connectible by cranked value means to a delivery line for the material to be transported, a piston in one pumping cylinder being arranged to perform a suction stroke to draw in material to be transported while a piston in the other pumping cylinder performs a pressure stroke to expel material to the delivery line, and means for moving the valve means at or near the end of a pressure stroke in one cylinder from a connecting position for said one cylinder to a connecting position for the other cylinder.

Known pumps of this type have various disadvantages such as, for example, that the pumping effect of the pistons tends to push the valve means away from the cylinder from which material is being expelled with the result that the material is spilled out of the joint therebetween. Moreover, it has been found that access to the interior of the delivery cylinders may be hindered by the presence of the cranked valve means.

In the complete Specification of our Patent Application No. 1478591, there is described and claimed a reciprocating pump, Claim 1 of which reads : - 1. A reciprocating pump for the transport df viscous, pulpy or plastic material, for example, concrete, comprising first and second pumping cylinders, a piston in one pumping cylinder being arranged to perform a suction stroke to draw in material to be transported while a piston in the other cylinder performs an expulsion stroke, to expel material to be transported.

a valve means located in a hopper for said material comprising a cranked duct arranged to connect said. cylinders alternately to a delivery line for the material to be transported, a projection being provided on said valve means arranged to cooperate with a projection in the hopper to prevent the duct being urged away from the cylinders by the pumping effect of the pistons and means for compensating for wear between portions of the pump in moving contact with each other.

In the pump described and claimed in our aforementioned Patent Specification it was believed that, due to the nature of the material to be pumped, it was necessary to provide means for compensating for wear between portions of the pump in moving contact with each other. It has now been found, contrary to earlier belief, that some materials, such as coal with an admixture to improve its flow qualities, being relatively soft cause little wear between the said portions in moving contact with each other.

The present invention relates to an improvement in or modification of the invention disclosed in our aforementioned Patent Specification, in which "the means for compensating for wear between portions of the pump in moving contact with each other" is omitted.

According to the present invention there is provided a reciprocating pump for the transport of viscous, pulpy or plastic material, for example, coal and admixture, comprising first and second pumping cylinders having first and second pistons guided therein, a piston in one pumping cylinder being arranged to perform a suction stroke to draw in material to be transported while a piston in the other cylinder performs an expulsion stroke, to expel material to be transported, a valve means comprising a substantially S-shaped duct arranged to connect said cylinders alternately to a delivery line for the material to be transported, and a projection being provided on said valve means arranged to cooperate with a projection in the hopper to prevent the duct being urged away from the cylinders by the pumping effect of the pistons.

Generally the duct which is oscillatable about an axis lying within an end portion of the duct remote from the cylinders between a position in which its receiving end is in register with the delivery end of one pumping cylinder and a position in which its receiving end is in register with the delivery end of the other pumping cylinder, movement being imparted to the duct through a lever arm arranged to pivot about a pivot axis.

An embodiment of the pump according to the present invention, adapted for transporting concrete, will now be described by reference to the accompanying drawings in which: Fig. 1 and 2 are each a diagrammatic plan showing the operation of a pump of the type herein defined; Fig. 3 is a longitudinal section of a pump according to the present invention.

The general principle of operation of a pump of the type herein defined will first be described with reference to Figures 1 and 2. A hopper 1 containing concrete 2 to be pumped has a lower side wall la receiving the open ends of pumping cylinders 3 and 4 each containing a respective piston 5 and 6. Each piston is mounted on the end of a hydraulically operable ram for reciprocation thereof in their respective cylinders. The opposite wall lb is apertured at a level higher than that of the cylinders 2 and 3 to receive an outlet end 7 of a hollow, substantially S-shaped duct 8 which is oscillatable about the axis of its outlet end 7 between a position in which its inlet end 9 is in register with the cylinder 3 (Fig. 1) and a position in which its inlet end 9 is in register with the cylinder 4 (Fig.

2). The outlet end 7 of the duct is connected to a delivery line (not shown). In the position shown in Fig. 1. the piston 6 is performing a suction stroke to draw concrete into the cylinder 4 as shown by arrows 10 while concrete previously introduced into cylinder 3 is being forced by the pressure stroke of piston 5 into the duct 8, as shown by arrow 11. When each of the pistons has reached the end of its stroke the duct 8 is caused to oscillate to the position shown in Fig. 2 when the reverse procedure takes place, concrete being drawn into cylinder 3 (arrows 12) and delivered from cylinder 4 (arrow 13).

The pump according to the embodiment of the present invention will now be described with reference to Figure 3, using the same reference numerals where applicable.

The inlet end 9 of the duct 8 is mounted for oscillation in the following way. In a wall lc of the hopper 1 above the cylinders 3 and 4 is secured a bearing housing 14 carrying bearings 15 and 16 for a pivot axle 17 having a hexagonal head 19 and a threaded distal end receiving a nut 19. The inner end of the axle 17 is secured to a lever arm 20 cast integrally with a annular portion which forms the inlet end 9 of the duct 8, and is secured by nuts 29 and bolts 30 to the main portion thereof by flanges 31 and 32 on the annular portion and duct 8 respectively. A flange 22 projecting downwardly from the annular portion co-operates with a projection 23 upstanding frdm a floor 1d of the hopper 1.The purpose of the flange 22 and the projection 23 is to prevent the duct 8 from being urged away from the mouths of the cylinders 3 and 4 by the pumping effect of the pistons 5 and 6 upon the concrete, with a consequent drop in efficiency.

An outlet end 7 of the duct 8 is formed by a separate end portion connected to the main portion of the duct 8 through a swivel joint 26 mounted in the wall 1b of the hopper. The outlet end 7 is fixedly secured, as by welding, to the wall lb of the hopper.

Oscillatory motion is imparted to the pivot axle 17 by means of the pistons of two double-acting hydraulic cylinders (not shown) in a manner similar to that de scribed in our aforementioned Patent Specification and thus to the inlet end 9 and main portion of the duct 8.

The swivel joint 26 may be of any suitable form such as, for example, a simple annular clamp having two semi-circular portions joined together by a hinge and an overcentre lever or by nuts and bolts; the swivel joint 26 comprises a seal 33 of, for example, rubber.

A safety grill 34, or the like, for the hoDper is provided and means may be provided for preventing operation of the hydraulic rams when the grill 34 is removed. The grill 34 is pivotally mounted on the hopper at 35 and a hydraulic valve controlled by the pivotal movement of the grill is included in the hydraulic lines to the rams so that hydraulic fluid to the rams is cut-off automatically as soon as the grill is raised, thus preventing external bodies or matter from falling into the hopper and incurring damage.

Various additions and! or modifications can be made to the pump. For example, one wall of the hopper 1, typically wall lc, could be arranged to be substantially vertical and hingedly connected to one of the other walls preferably a side wall of the hopper 1 so that the hopper shell can be swung away from the wall 1c to provide access to the ends of the cylinders 3, 4 and to the inside of the hopper. Sealing means (not shown) can be provided between the wall 1c and the adjacent walls of the hopper to prevent leakage of material from the hopper.

WHAT WE CLAIM IS: 1. A reciprocating pump comprising, first and second pumping cylinders, having first and second pistons respectively guided therein, a piston in one pumping cylinder being arranged to perform a suction stroke to draw in material to be transported from a hopper while a piston in the other cylinder performs an expulsion stroke to expel material to be transported, a valve means comprising a substantially S-shaped duct arranged to connect said cylinders alternately to a delivery line for the material to be transported and a projection being provided on said valve means arranged to cooperate with a projection in the hopper to prevent the duct being urged away from the cylinders by the pumping effect of the pistons.

2. A pump according to Claim 1, wherein there is provided a pivot axle capable of oscillating about its axis and a lever arm connecting the pivot axle to the duct for moving the duct from a connecting position for one cylinder to a connecting position for the other cylinder.

3. A pump according to Claim 2, wherein a terminal portion of the duct, adjacent said cylinders and to which the lever arm is connected, and an outlet terminal portion of the duct are formed separately from the main portion of the duct which is arranged to be readily mountable and demountable from the pump.

4. A pump according to Claim 3, wherein the main portion of the duct is connected to one of said terminal portions by a swivel joint.

5. A pump according to Claim 4, wherein the swivel joint is a releasable twopart annular clamp surrounding the duct.

6. A pump according to Claim 5, wherein the swivel joint is lockable and releasable by means of an over-centre lever.

7. A pump according to Claim 5, wherein the two parts of the swivel joint are held together by nut and bolt means.

8. A pump according to any one of the preceding claims, wherein a wall of the hopper is hingedly connected to the rest of the hopper shell whereby the hopper shell can be hinged away from the said wall.

9. A pump according to any one of the preceding claims further comprising a cover member, such as a grill for said hopper and means coupled to the cover member for preventing operation of the valve means when the cover is raised from the hopper.

10. A pump according to Claim 9, wherein the valve means is operable by hydraulic ram means and the means coupled to the cover for preventing operation of the valve means is a hydraulic valve controlled by movement of the cover whereby hydraulic fluid to the ram means is cut off when the cover is raised from the hopper.

11. A pump according to Claim 10, wherein the cover is pivotally mounted to the hopper and the hydraulic valve is controlled by pivotal movement of the cover.

12. A reciprocating pump, substantially as hereinbefore described with reference to the accompanying drawings.

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

Claims (12)

**WARNING** start of CLMS field may overlap end of DESC **. ends of the cylinders 3, 4 and to the inside of the hopper. Sealing means (not shown) can be provided between the wall 1c and the adjacent walls of the hopper to prevent leakage of material from the hopper. WHAT WE CLAIM IS:

1. A reciprocating pump comprising, first and second pumping cylinders, having first and second pistons respectively guided therein, a piston in one pumping cylinder being arranged to perform a suction stroke to draw in material to be transported from a hopper while a piston in the other cylinder performs an expulsion stroke to expel material to be transported, a valve means comprising a substantially S-shaped duct arranged to connect said cylinders alternately to a delivery line for the material to be transported and a projection being provided on said valve means arranged to cooperate with a projection in the hopper to prevent the duct being urged away from the cylinders by the pumping effect of the pistons.

2. A pump according to Claim 1, wherein there is provided a pivot axle capable of oscillating about its axis and a lever arm connecting the pivot axle to the duct for moving the duct from a connecting position for one cylinder to a connecting position for the other cylinder.

3. A pump according to Claim 2, wherein a terminal portion of the duct, adjacent said cylinders and to which the lever arm is connected, and an outlet terminal portion of the duct are formed separately from the main portion of the duct which is arranged to be readily mountable and demountable from the pump.

4. A pump according to Claim 3, wherein the main portion of the duct is connected to one of said terminal portions by a swivel joint.

5. A pump according to Claim 4, wherein the swivel joint is a releasable twopart annular clamp surrounding the duct.

6. A pump according to Claim 5, wherein the swivel joint is lockable and releasable by means of an over-centre lever.

7. A pump according to Claim 5, wherein the two parts of the swivel joint are held together by nut and bolt means.

8. A pump according to any one of the preceding claims, wherein a wall of the hopper is hingedly connected to the rest of the hopper shell whereby the hopper shell can be hinged away from the said wall.

9. A pump according to any one of the preceding claims further comprising a cover member, such as a grill for said hopper and means coupled to the cover member for preventing operation of the valve means when the cover is raised from the hopper.

10. A pump according to Claim 9, wherein the valve means is operable by hydraulic ram means and the means coupled to the cover for preventing operation of the valve means is a hydraulic valve controlled by movement of the cover whereby hydraulic fluid to the ram means is cut off when the cover is raised from the hopper.

11. A pump according to Claim 10, wherein the cover is pivotally mounted to the hopper and the hydraulic valve is controlled by pivotal movement of the cover.

12. A reciprocating pump, substantially as hereinbefore described with reference to the accompanying drawings.