Fluid pump apparatus

Abstract: In fluid pump apparatus in which the reciprocating action of a piston (3) provided in a cylinder (21) draws fluid into a valve chamber (1) and pumps fluid (14) from the valve chamber, a pressure-action chamber (5a) is provided between the cylinder and the valve chamber, the pressure-action chamber being filled with a liquid (28) that has a different specific gravity than that of the said fluid. A passage (17) that connects the pressure-action chamber and the valve chamber is provided at a position at which the height relative to the pressure-action chamber and the valve chamber is such that the liquid does not flow owing to the difference in specific gravity between the liquid and the fluid.

Description: This invention relates to fluid pump apparatus for ultrahigh pressure pumping of fluids. Pumps include reciprocating pumps in which the reciprocating action of a piston is used to open and close valves to pump a fluid such as water, for example. In accordance with the configuration of the piston, reciprocating pumps are divided into the bucket type, the plunger type and the piston type. Each type of reciprocating pump has its own uses, but in all such pumps the sliding parts are prone to wear. In the prior art, there is known a technique whereby the fluid is prevented from coming into direct contact with the sliding parts of the reciprocating pump, consisting of providing a diaphragm in front of the piston and filling the space on the inner side of the diaphragm with fluid in order to transmit the force of the piston (Japanese Patent Publication No. 48-35405). However, in such a configuration the diaphragm is exposed to the fluid, and as a result the diaphragm wears quickly and has to be replaced. The diaphragm has to be replaced especially frequently when the pump is being used in cement mills, for example. When plunger pumps, too, are used in cement mills, for example, the rapid wear of packings caused by cement particles has limited pumping pressures to 200 kgf/cm². The flow of fluid is limited and controlled by various types of valves. Figures 14 and 15 show a valve device used on plunger pumps, a type of pump which is often used for high-pressure applications. This valve device is constituted by a tubular seat 100, a valve-piece 102 with a surrounding flange 101, and a valve spring 103 which urges the valve-piece 102 against the seat 100. Because plunger pumps are used to pump materials such as cement clinker, in the conventional valve device solid particles entrained in the fluid may be caught between the valve-piece 102 and the seat 100. The tubular shape of the seat 100 used in the conventional valve device makes it easy for solid particles to pass through. In addition, because the seat 100 and the valve-piece 102 are made of metal, the operation of the valve may be adversely affected by solid particles that are caught therebetween. The result is that it has sometimes been impossible to pump a constant amount of fluid at a constant rate, so that operation of the pump was accompanied by a decline in efficiency. Furthermore, solid particles caught between the seat 100 and the valve-piece 102 can damage the seat and valve-piece, leading to leakage of fluid. Conventionally, therefore, the valve device has to be replaced at this point, which interrupts operations. This led to the invention of Japanese Patent Application 62-237996, a valve device for preventing the inflow of solid particles present in fluid and increasing the durability of the device. Such a valve device (see Figures 16 and 17) comprises a seat 107 having a valve seat 104 formed as a concave surface 105 corresponding to part of a spherical surface, and a prescribed number of fluid passages 106 which are formed in the seat 107 and open into the concave surface 105. There are also a valve-piece 108 that has a surface corresponding to the shape of the concave surface 105 of the valve seat 104, and a valve cover 110 and spring retainer 111 that maintain the valve-piece 108 on the concave surface 105 of the seat 104 via a valve spring 109. In the valve device thus configured, at least one of the seat 107 and the valve-piece 108 is either formed of, or covered with, a hard resilient material, or one is formed of a hard resilient material and the other is covered with a hard resilient material. In addition, wood may be used instead of the hard resilient material. With the valve device thus configured, the fluid passages 106 formed in the seat 107 have a small diameter which makes it difficult for solid particles to pass therethrough. Even if solid particles should pass through the fluid passages 106 and get caught between the seat 107 and the valve-piece 108, the resilience of the valve seat and/or the valve-piece ensures that the functioning of the valve device will not be obstructed. However, a valve device thus configured is less adequate for pumping at higher pressures because increasing the amount being pumped can cause the valve-piece 108 to vibrate during the inflow of fluid. GB-A-272 374 and DE-A-805 006 disclose reciprocating pumps in which a diaphragm is disposed between the piston of the pump and the fluid to be pumped. In GB-A-272 374 perforated cups are located on either side of the diaphragm to protect it against damage due to excessive distortion. In DE-A-805 006 a perforated screen is located between the diaphragm and the fluid to be pumped. DE-A-2 218 781 discloses fluid pump apparatus having the pre-characterising features of claim 1. According to the present invention there is provided fluid pump apparatus comprising:- a piston; a cylinder in which the piston reciprocates; a valve chamber having an inlet and an outlet, each provided with a valve, reciprocating action of the piston in the cylinder serving to draw fluid into the valve chamber and to pump this fluid from the valve chamber; a pressure-action chamber provided between the cylinder and the valve chamber, this pressure-action chamber being filled with a liquid that has a different specific gravity than that of said fluid; and a passage that connects the pressure-action chamber and the valve chamber and that is provided at a position at which the height relative to the pressure-action chamber and the valve chamber is such that the liquid does not flow owing to the difference in specific gravity between the liquid and the fluid; characterised in that the fluid pump apparatus is for ultrahigh pressure pumping of fluids, in that the pressure-action chamber is provided with a partitioning pressure action member that divides the pressure-action chamber into a cylinder side (A) and a valve chamber side (B), and in that screening means is provided between the partitioning pressure action member and the passage that connects the pressure-action chamber to the valve chamber, this screening member comprising elongate passages inclined toward the said passage for limiting the flow to the pressure action member to particles in the fluid that do not exceed a fixed size. The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a sectional view of a first embodiment of fluid pump apparatus not according to the present invention; Figure 2 is an enlarged sectional view of part of the apparatus shown in Figure 1; Figure 3 is a sectional view of a second embodiment of fluid pump apparatus not according to the present invention; Figure 4 is a sectional view of a third embodiment of fluid pump apparatus according to the present invention; Figure 5 is a sectional view of a fourth embodiment of fluid pump apparatus according to the present invention, Figure 6 being a view of a detail of the apparatus; Figure 7 is a sectional view of a fifth embodiment of fluid pump apparatus according to the present invention in the form of an ultrahigh pressure pump for use, for example, in cement mills; Figure 8 is a sectional view of a valve device shown in Figure 7; Figure 9 is a perspective view of the valve device of Figure 8, shown disassembled; Figure 10 is a plan view of a valve housing shown in Figure 9; Figure 11 is a sectional view taken along line A--A of Figure 10; Figure 12 is a plan view of a seat shown in Figure 8; Figure 13 is a sectional view taken along line A--A of Figure 12; Figures 14 and 15 are a sectional view and a disassembled perspective view of a conventional valve device; and Figures 16 and 17 are a sectional view and a disassembled perspective view of conventional valve device. Figure 1 is a sectional view of a plunger pump used for pumping fluid containing a high level of particles, such as cement particles, for example. In Figure 1, fluid pump apparatus comprises a valve box 2 provided with a valve chamber 1, a plunger box 4 provided with a piston in the form of a plunger 3, and a box 5 providing a pressure-action chamber 5a disposed between the valve box 2 and the plunger box 4. The valve box 2 has an inlet passage 6 and an outlet passage 7 that communicate with the valve chamber 1 and which are provided with an inlet valve 8 and an outlet valve 9, respectively. The inlet valve 8 and the outlet valve 9 each have a seat 11 which is formed with a valve seat having a concave, semi-spherical shape and in which there are a multiplicity of small holes 10 that extend axially from the concave valve seat; a valve-piece 12 that has a spherical shape corresponding to the concave valve seat; and a valve spring 13 that urges the valve-piece 12 against the valve seat. The holes 10 are for limiting the entry into the valve chamber 1 of particles in the fluid 14 that exceed a given size. The valve-piece 12 of the inlet valve 8 can open in the direction of the valve chamber 1 and is therefore urged toward its seat 11 by its valve spring 13 via a valve retainer 15, one end of the valve spring 13 being engaged with the inner wall of the valve chamber 1. The valve-piece 12 of the outlet valve 9 opens away from the valve chamber 1 and is therefore urged against its seat 11 by its valve spring 13 being provided between the valve box 2 and a valve cover 16. Provided in the side wall 2a of the valve box 2 is a passage 17 that connects the pressure-action chamber 5a with the interior of the valve chamber 1, the passage 17 opening into the lower part of a recess 18 formed in the side wall 2a of the valve box 2. The box 5 that provides the pressure-action chamber 5a is provided with a screening member 19 disposed between the recess 18 and the pressure-action chamber 5a, as shown in the enlarged view of Figure 2. A mesh screen, for example, is used for the screening member 19, and formed therein are passages 20 to prevent the entry into the pressure-action chamber 5a of particles that exceed a given size. The passages 20 may be formed integrally in the side of the valve box 5, and are set at a prescribed inclination toward the passage 17 side. The end of plunger 3 maintained within a cylinder 21 in the plunger box 4 via a V-packing 22 projects into the pressure-action chamber 5a and is reciprocated at high speed by drive means (not illustrated). A resilient membrane 23 is provided in the pressure-action chamber 5a to divide the pressure-action chamber 5a into a cylinder 21 side A and a valve chamber 1 side B. The chamber 5a is filled on the cylinder 21 side A of the resilient membrane 23 with an operating medium 25, such as oil, via an oil passage 24 of the plunger box 4. With the above configuration, when suction operation of the plunger 3 causes the resilient membrane 23 to contract, reducing the volume on the cylinder 21 side A of the pressure-action chamber 5a, a corresponding amount of fluid 14 flows into the valve chamber 1. At this time, particles in the fluid 14 that exceed a given size cannot pass through the seat 11 of the valve 8 and are thus prevented from flowing into the valve chamber 1. Also, as particles in the fluid 14 that exceed a given size cannot pass through the screening member 19, any such particles in fluid 14 that flow into the valve chamber 1 cannot enter the valve chamber side B of the pressure-action chamber 5a. The expulsion operation of the plunger 3 expands the resilient membrane 23, causing fluid 14 that has entered the valve chamber 1 to be expelled from the valve chamber 1. In Figure 3, parts that are the same as parts shown in Figure 1 have been given the same reference numerals. In the second embodiment, a resilient membrane 26 directly covers the plunger 3 and the reciprocating action of the plunger 3 directly expands the resilient membrane 26. In this embodiment, the passages 20 provided in a screening member 27 are not disposed facing the passage 17 but are instead located higher, which fully prevents the entry of any particles in the fluid 14. When pumping operations are being carried out where there are high levels of particles, such as in a cement mill, large particles contained in the fluid 14 can be fully prevented from entering the valve chamber 1 side B by filling the valve chamber 1 side B of the pressure-action chamber 5a with a liquid such as water that contains no particles, prior to the start of the pumping. Figure 4 shows an embodiment of the present invention. In Figure 4, parts that are the same as parts shown in Figure 1 have been given the same reference numerals. In this third embodiment, the side wall 2a of the valve box 2 is provided with a passage 17 that connects the pressure-action chamber 5a with the valve chamber 1. As explained below, the position of the passage 17 is determined according to the difference in specific gravity between a liquid 28 and the fluid 14. When the liquid has a higher specific gravity than the fluid, the passage 17 is located at a higher position in the pressure-action chamber 5a, and when the liquid 28 has a lower specific gravity the passage 17 is positioned lower. In the illustrated example, the position where the passage 17 opens into the pressure-action chamber 5a is higher than the inlet of the valve chamber 1. Thus, in this embodiment, the position of the passage 17 is determined according to the relationship between the heights of the pressure-action chamber 5a and the valve chamber 1 and a consideration of the specific gravities of the liquid 28 and the fluid 14. The end of the plunger 3 maintained within the cylinder 21 in the plunger box 4 via V-packing 22 projects into the pressure-action chamber 5a and is reciprocated at high speed by drive means (not illustrated). A resilient membrane 23 is provided in the pressure-action chamber 5a to divide the pressure-action chamber 5a into a cylinder 21 side A and a valve chamber 1 side B. The chamber 5a is filled on the cylinder 21 side A of the resilient membrane 23 with an operating medium 25, such as oil, via an oil passage 24 of the plunger box 4. In addition, the chamber 5a on the valve chamber 1 side B of the membrane 23 and part of the passage 17 are filled with the liquid 28, such as oil, which has a lower specific gravity than the fluid 14 used in a cement mill, for example, and does not mix with the fluid 14. The liquid 28 comes into contact with the fluid 14 part-way along the passage 17. Provided between the pressure-action chamber 5a and the passage 17 is a screening member 29 that uses a mesh screen, for example, to prevent particles that exceed a given size from entering the pressure-action chamber 5a. The screening member 29 may be formed as an integral part of the valve box 5 which provides the pressure-action chamber 5a, and the passages 20 therein are set at a downward inclination toward the passage 17 side. With the above configuration, suction operation of the plunger 3 causes the resilient membrane 23 to contract, reducing the volume on the cylinder 21 side A of the pressure-action chamber 5a and increasing the volume on the valve chamber 1 side B. The change in volume results in a rise in the level of the liquid 28 in the passage 17. Also, an amount of fluid 14 corresponding to the change in volume flows into the valve chamber 1 as the inlet valve 8 opens. The expulsion operation of the plunger 3 causes the resilient membrane 23 to expand via the operating medium 25 and, with the reduction in the volume of the valve chamber 1 side B, the liquid 28 in the valve chamber 1 side B of the pressure-action chamber 5a is expelled. Also, the level of the liquid 28 in the passage 17 decreases and a corresponding amount of fluid 14 is forced out as the outlet valve 9 opens. The liquid 28 is only forced part-way along the passage 17 and does not flow over to the valve chamber 1 side. Figure 5 shows an embodiment of the present invention. In Figure 5, parts that are the same as parts shown in Figure 1 have been given the same reference numerals. In this embodiment, a pre-chamber 30 filled with the liquid 28 is also provided on the outside of the valve box 5. The pre-chamber 30 communicates with the liquid 28 in the passage 17 by means of a branch pipe 31. With this embodiment, the point of confluence of the liquid 28 and the fluid 14 does not move above the pre-chamber 30, and therefore the liquid 28 in the pressure-action chamber 5a can be kept fresh by changing the liquid 28 in the pre-chamber 30. Figure 6 illustrates the insertion of a liquid 32 having a specific gravity that is midway between the specific gravities of the liquid 28 and the fluid 14 and which, in addition, does not mix with the fluid 14. With this arrangement, there is no direct contact between the liquid 28 and the fluid 14. A partitioning medium disposed between the liquid 28 and the fluid 14 may be used in place of the liquid 32. In the above embodiments, a liquid 28 is used having a lower specific gravity than the fluid 14, but a liquid having a higher specific gravity than the fluid 14 may also be used. In such a case, the passage connecting the pressure-action chamber 5a with the valve chamber 1 should be provided towards the upper part of the pressure-action chamber 5a. A premise for such an arrangement is that the positional relationship between the height of the pressure-action chamber 5a and the valve chamber 1 will be adjusted. Figure 7 shows an embodiment of the present invention in the form of an ultrahigh pressure pump for use in cement mills, for example. In Figure 7, parts that are the same as parts shown in Figure 1 have been given the same reference numerals. In this embodiment, the ultrahigh pressure pump consists of a valve box 2 that has a valve chamber 1; a plunger box 4 containing a piston in the form of a plunger 3; and a valve box 5 providing a pressure-action chamber 5a that is disposed between the valve box 2 and the plunger box 4. The valve box 2 has an inlet passage 6 and an outlet passage 7 that communicate with the valve chamber 1 and which are provided with an inlet valve 80 and an outlet valve 81, respectively. As shown in Figures 8 to 13, the inlet valve 80 and the outlet valve 81 each have a seat 84 in the face 82 which are formed a multiplicity of valve seats 83 (eight, in the illustrated example) spaced at regular intervals around the edge, each shaped into a concave form that corresponds to part of a spherical surface; spherical valve-pieces 85 arranged on the valve seats 83; and a valve housing 87 that presses the valve-pieces 85 on to the valve seats 83 by means of springs 86. In each of the valve seats 83 in the seat 84, there are formed multiple fluid passages 88 (three in each case, in the illustrated example) that extend axially throughout the seat 84. Disposed around the edge of the valve housing 87 are fluid passages 89 corresponding to the valve seats 83 and into which the valve-pieces 85 fit. The exit end of each of the fluid passages 89 is formed into a smaller diameter portion by a lip 90. One end of each of the valve springs 86 is held in place at a respective lip 90. The valve housing 87 and seat 84 are each provided with respective central bolt through-holes 91 and 92 whereby they are bolted together by a bolt 93 and a nut 94. In addition to metal, the valve-pieces 85 and/or the seat 84 may be made of, or covered with, a hard resilient material such as synthetic resin, for example. In the side wall 2a of the valve box 2 is a passage 17 that connects the pressure-action chamber 5a with the interior of the valve chamber 1, and provided at the opening of the passage at the pressure-action chamber 5a end is a screening member 29 constituted of a mesh screen or the like that limits the entry of particles that exceed a given size. The end of plunger 3 maintained within a cylinder 21 in the plunger box 4 via a V-packing 22 projects into the pressure-action chamber 5a and is reciprocated at high speed by drive means (not illustrated). A resilient membrane 23 is provided in the pressure-action chamber 5a to divide the pressure-action chamber 5a into a cylinder 21 side A and the valve chamber 1 side B. The chamber 5a on the cylinder 21 side A of the resilient membrane 23 is filled with an operating medium 25, such as oil. Also, the chamber 5a on the valve chamber 1 side B of the membrane 23 is filled with a liquid such as oil having a specific gravity that differs from that of the fluid, so that the pumped fluid does not enter the pressure-action chamber 5a. With the above configuration, when suction operation of the plunger 3 causes the resilient membrane 23 to contract, reducing the volume on the cylinder 21 side A of the pressure-action chamber 5a, the result is that the valve-pieces 85 of the inlet valve 80 open against the resistance of the springs 86, and cement mill fluid 14 flows into the valve chamber 1. At this time, the valve-pieces 85 of the outlet valve 81 are drawn in the direction of their closed positions, and therefore remain closed. Before the fluid can flow into the valve chamber 1, entrained particles that exceed a given size are removed by the fluid passages 88. The expulsion operation of the plunger 3 expands the resilient membrane 23, causing fluid 14 that has entered the valve chamber 1 to open the outlet valve 81 and be pumped out. Because the operation of the valves 80 and 81 takes the form of small amplitude movements of the numerous valve-pieces 85, vibration accompanying the opening and closing action of the valves can be prevented. The provision of a screening member stops the entry of particles in the fluid that exceed a given size, thus preventing large particles from coming into direct contact with the pressure action member (in the form of a membrane) and eliminating a source of wear and damage to the pressure-action member, and as such increasing durability. It can allow pressures of around 500kgf/cm² to be achieved, and therefore can provide major improvements in efficiency if employed for pumping operations in civil engineering projects. The provision of a resilient membrane ensures reliable transmission of the piston action. Using a specific gravity differential between the fluid and a liquid on the valve chamber side of the pressure action member can prevent the liquid flowing from the pressure-action chamber into the valve chamber, so that there is no inflow of the fluid into the pressure-action chamber, and hence no wear and tear to the frictional parts of the piston. This results in a major boost in pump output levels, compared to conventional apparatus. The freshness of the liquid in the pressure-action chamber can be maintained by changing the liquid in a pre-chamber, while using separating means between the liquid and the fluid can provide a reliable way to prevent mingling between liquid and fluid. Using a suitable operating medium on the cylinder of the pressure-action chamber can provide for piston lubrication. The use of a plurality of fluid passages in the seat member of at least the inlet valve of the valve chamber means that particles in the fluid that exceed a given size can be removed before reaching the valve chamber. The use of a plurality of valve seats, each with a respective plurality of fluid passages, enables valve-piece vibration to be prevented, and can provide reliable function and increased durability.

Claims: Fluid pump apparatus comprising:- a piston (3); a cylinder (21) in which the piston reciprocates; a valve chamber (1) having an inlet (6) and an outlet (7), each provided with a valve (8 or 80, 9 or 90), reciprocating action of the piston in the cylinder serving to draw fluid (14) into the valve chamber and to pump this fluid (14) from the valve chamber; a pressure-action chamber (5a) provided between the cylinder and the valve chamber, this pressure-action chamber being filled with a liquid (28) that has a different specific gravity than that of said fluid (14); and a passage (17) that connects the pressure-action chamber and the valve chamber and that is provided at a position at which the height relative to the pressure-action chamber and the valve chamber is such that the liquid (18) does not flow owing to the difference in specific gravity between the liquid (28) and the fluid (14); characterised in that the fluid pump apparatus is for ultrahigh pressure pumping of fluids, in that the pressure-action chamber (5a) is provided with a partitioning pressure action member (23) that divides the pressure-action chamber into a cylinder side (A) and a valve chamber side (B), and in that screening means (29) is provided between the partitioning pressure action member (23) and the passage (17) that connects the pressure-action chamber (5a) to the valve chamber (1), this screening means comprising elongate passages (20) inclined toward the said passage (17) for limiting the flow to the pressure action member to particles in the fluid (14) that do not exceed a fixed size. Apparatus according to claim 1 wherein the screening means (29) is formed integrally with the pressure action member (5a). Apparatus according to any one of claims 1 to 2, wherein the pressure action member is a resilient membrane (23). Apparatus according to any one of claims 1 to 3, wherein a pre-chamber (30) is provided to contain said liquid (28), the liquid (28) in this pre-chamber (30) communicating with the liquid (28) in said passage (17). Apparatus according to any one of claims 1 to 4, wherein a partitioning medium (32) is provided between said liquid (28) and said fluid (14) that conforms to change in level. Apparatus according to any one of claims 1 to 5, wherein at least for the inlet side valve (8 or 80) a valve device is used that limits the flow through this valve to particles in the fluid (14) that do not exceed a fixed size. Apparatus according to any one of claims 1 to 6, wherein at least the valve of the inlet of the valve chamber comprises:- (a) a seat member (84) in a face of which are formed a plurality of valve seats (83), each of said seats having a concave shape that corresponds to part of a spherical surface; (b) a plurality of fluid passages (88) in said seat member, for each of said valve seats there being a respective plurality of such fluid passages in the seat member and communicating with the valve seat; (c) a plurality of valve pieces (85), each of the valve pieces being in a respective one of said valve seats and each having a spherical surface that corresponds to the surface of the valve seat; and (d) a valve housing (87) provided with resilient means (86) that resiliently presses the valve pieces on to the surfaces of the respective ones of the valve seats.

Inventors: KOIWA YOSHINOBU, KOIWA, YOSHINOBU
Applicants: FUJIMORI SHUICHI, KELBIN CO LTD, KOIWA YOSHINOBU, LITTLE ROCK LTD, FUJIMORI, SHUICHI, KABUSHIKI KAISHA LITTLE ROCK, KELBIN CO., LTD., KOIWA, YOSHINOBU
Application year: 1989
Main classification: F04B21
IPC codes: F04B43, F04B53