JP4147199B2 - Plunger pump - Google Patents

Description

  The present invention relates to a plunger pump for transporting liquid by reciprocating movement of a plunger, and more particularly to a seal structure for preventing leakage of liquid from a pump chamber to a drive unit side.

  The plunger pump generally includes a cylinder, a plunger that reciprocates within the cylinder, and a drive unit that drives the plunger. In addition, a pump chamber is provided on the side opposite to the drive unit so that liquid can be sucked and discharged by reciprocating movement of the plunger.

  When the plunger pump is operated, the pump chamber is pressurized in the discharge process, and the liquid in the pump chamber passes between the inner peripheral surface of the cylinder and the outer peripheral surface of the plunger and tries to enter the drive unit side. In order to prevent or suppress such intrusion of liquid, a cylinder is conventionally provided with a seal (see Patent Document 1).

Further, in the contact-type seal, fine foreign matter may be generated due to abrasion with the plunger and mixed into the transport liquid. Therefore, conventionally, a non-contact type high-pressure seal is provided on the pump chamber side. For example, as disclosed in Patent Document 2, the non-contact type high-pressure seal forms a liquid film between the plunger and the seal, forms a liquid film there, and performs sealing with the liquid film. Is. Such a non-contact type high-pressure seal has no adverse effects due to wear, but a slight amount of liquid leaks. Therefore, a contact-type low-pressure seal such as a U-packing is further provided on the drive unit side (see Patent Document 1).
JP-A-8-21368 Japanese Patent Laid-Open No. 10-18777

  In the conventional plunger pump as described above, a part of the liquid that has passed through the gap between the high-pressure seal and the plunger becomes a jet and directly hits the low-pressure seal. May deteriorate.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a plunger pump that prevents liquid leaking from a high pressure seal from hitting the low pressure seal at high speed.

  In order to achieve the above object, a plunger pump (10) according to the present invention drives a cylinder (12), a plunger (14) reciprocally disposed in the cylinder (12), and a plunger (14). And a pump chamber (22) disposed on the opposite side of the drive unit and communicating with the inside of the cylinder (12), and an inner peripheral surface of the cylinder (12) on the pump chamber (22) side A non-contact type high pressure seal (34), a contact type low pressure seal (36) disposed on the inner peripheral surface of the cylinder (12) on the drive side, a high pressure seal (34) and a plunger (14) A guard (62, 162) provided between the high-pressure seal (34) and the low-pressure seal (36), and a high-pressure seal (34) With guard (62, 162) A first space (58) having a cross-sectional area larger than the cross-sectional area of the minimum gap between the high-pressure seal (34) and the plunger (14), a guard (62, 162) and a low-pressure seal ( 36) and a second space (70) having a cross-sectional area larger than the cross-sectional area of the minimum gap between the guard (62, 162) and the plunger (14). It is a feature.

  In this configuration, the flow of the liquid that has passed through the high-pressure seal (34) is decelerated and dispersed by the presence of the first space portion (58). And most of the liquid flow is blocked by the guards (62, 162). Furthermore, the liquid flow that has passed through the guards (62, 162) is also decelerated and dispersed by the second space (70). Therefore, the liquid hitting the low pressure seal (36) is very small and the flow is low.

  As the guard (62), an annular body in which one end is the maximum diameter portion (64) and the minimum diameter portion (68) is formed on the other end side, more specifically, a substantially truncated conical annular shape. The body is considered. In this case, the maximum diameter portion (64) is brought into contact only with the outer peripheral portion (72) at one end of the low pressure seal (36). The smallest diameter portion (68) is positioned to face the high pressure seal (34).

  As a result, the inner peripheral portion (54) of the low-pressure seal (36) is not constrained, and the original function as the low-pressure seal (36) is not impaired, and reliable sealing can be performed. Moreover, since the minimum diameter part (68) is located in the high pressure seal (34) side, the flow of the liquid from a high pressure seal (34) can be blocked effectively. A second space (70) is formed inside the guard (62).

  The guard (162) may be integrally formed on the inner peripheral surface of the cylinder (12).

  It is also effective to provide a sealing member (44) made of an elastic material on the outer periphery of the high-pressure seal (34). As a result, the dimensional error of the high-pressure seal (34) made of a relatively hard material can be absorbed, and the position stability can be ensured.

  As described above, according to the present invention, the first space portion (58), the second space portion (70), and the guards (62, 162) are disposed between the high pressure seal (34) and the low pressure seal (36). ) Is provided, the majority of the liquid flow that has passed through the high pressure seal (34) can be blocked and slowed down. Therefore, even if a liquid hits the low pressure seal (36), the damage is small and the deterioration of the low pressure seal (36) can be prevented.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating directions such as “up” and “down” are convenient terms based on the state shown in the figure.

  FIG. 1 is a longitudinal sectional view partially showing a first embodiment of a plunger pump according to the present invention, and FIG. 2 is an enlarged view of a portion A in FIG. The illustrated plunger pump 10 includes a cylinder 12, a plunger 14 that reciprocates within the cylinder 12, and a drive unit (not shown) that drives the plunger 14.

  Various forms such as the cylinder 12 being formed on the pump casing itself are conceivable. In this embodiment, the first manifold 18 connected to the pump casing 16 and the first manifold 18 are connected. The second manifold 20 is formed. The plunger pump 10 according to the present embodiment is a multiple pump having a plurality of cylinders 12 and plungers 14, and manifolds 18 and 20 are used for this purpose.

  A pump chamber 22 communicating with the inside of the cylinder 12 is defined in the second manifold 20 located on the side opposite to the drive unit. A lower portion of the pump chamber 22 communicates with a suction port 24 formed in the first manifold 18, and a suction valve 26 is disposed between the pump chamber 22 and the suction port 24. A discharge valve 28 is disposed above the pump chamber 22, and the liquid discharged from the discharge valve 28 is sent to a discharge port 30 formed in the second manifold 20.

  Although not shown, the drive unit includes a crankcase that constitutes a part of the pump casing 16 and a drive source such as an electric motor disposed outside the crankcase, as is well known. In the crankcase, there are provided a crankshaft that rotates by receiving a driving force of a driving source, a plunger member that is connected to the plunger 14 via a plunger rod 32, and a connection rod that connects the plunger member and the crankshaft. It has been. When the drive source is driven and the crankshaft in the crankcase is rotated in a predetermined direction, the rotational force is transmitted through the connection rod, the plunger base, and the plunger rod 32, and the plunger 14 reciprocates in the cylinder 12.

  As shown in FIG. 2, the cylinder 12 includes a high-pressure seal 34 and a low-pressure seal in order to block liquid leaking to the drive unit side between the inner peripheral surface of the cylinder 12 and the outer peripheral surface of the plunger 14. 36.

  The high-pressure seal 34 is a non-contact type and is composed of a cylindrical body made of a relatively hard material. The high-pressure seal 34 is fitted to a diameter-expanded portion 38 formed on the cylinder chamber 12 on the pump chamber 22 side of the first manifold 18. The high pressure seal 34 fitted to the expanded diameter portion 38 is connected by a communication pipe 40 for liquid-tightly connecting the manifolds 18 and 20 in a state where the first manifold 18 and the second manifold 20 are connected. Pressed down and fixed.

  The inner diameter of the high-pressure seal 34 is extremely slightly larger than the outer diameter of the plunger 14, and a minute gap is formed between the inner peripheral surface of the high-pressure seal 34 and the outer peripheral surface of the plunger 14 in the illustrated fixed state. . As will be described below, when the pump is driven, a liquid film is formed between the inner peripheral surface of the high-pressure seal 34 and the outer peripheral surface of the plunger 14, thereby suppressing liquid leakage from the pump chamber 22 to the drive unit side. The In addition, since the plunger 14 does not substantially contact the inner peripheral surface of the high-pressure seal 34 when the pump is driven, minute foreign matters due to wear are not mixed into the liquid in the pump chamber 22.

  Reference numeral 44 denotes a sealing member such as an O-ring that is disposed on the outer peripheral portion of the high-pressure seal 34 and seals between the communication pipe 40 and the high-pressure seal 34 in a liquid-tight manner. This is made of an elastic material such as synthetic rubber, can absorb the dimensional error of the hard high-pressure seal 34, and exhibits effects such as preventing the displacement of the high-pressure seal 34.

  The low-pressure seal 36 is a contact type provided to block the liquid slightly leaked from the non-contact type high-pressure seal 34, and is an annular body made of an elastic material (for example, synthetic rubber). The low-pressure seal 36 is fitted into a diameter-expanded portion 46 formed on the drive portion side of the cylinder 12. The low pressure seal 36 fitted to the enlarged diameter portion 46 is pressed and fixed by the seal presser 48 in a state where the first manifold 18 and the pump casing 16 are connected.

  In the illustrated embodiment, a so-called U-packing in which a groove 50 is formed on one end surface portion over the entire circumference is used as the low-pressure seal 36. In a state where the low pressure seal 36 is fixed at a predetermined location, the groove 50 is disposed on the pump chamber 22 side. Further, an annular coil spring 52 is fitted in the groove 50, whereby the lip portion 54 inside the groove 50 is brought into close contact with the outer peripheral surface of the plunger 14 to ensure sealing.

  Reference numeral 56 denotes a metal holder embedded in the low-pressure seal 36, which gives a certain rigidity to the low-pressure seal 36 made of an elastic material and prevents displacement and deformation.

  Further, the inner peripheral surface of the cylinder 12 is expanded in a region between the high pressure seal 34 and the low pressure seal 36. The portion 58 forms an annular first space 58 between the outer peripheral surface of the plunger 14 in a state where the plunger 14 is inserted into the cylinder 12. The first space 58 is communicated with the suction port 24 via a flow path 58 formed in the first manifold 18.

  As described above, when the plunger pump 10 is driven, the high pressure seal 34 is a non-contact type, so that liquid slightly passes from the pump chamber 22 through the high pressure seal 34 to the low pressure seal 36. At this time, since the inside of the pump chamber 22 is at a high pressure in the discharge process, when the liquid passes through a minute gap between the high-pressure seal 34 and the plunger 14, the liquid becomes a high-speed jet toward the low-pressure seal 36. However, the first space 58 is formed between the high-pressure seal 34 and the low-pressure seal 36 so that the cross-sectional area is larger than the cross-sectional area of the minimum gap between the high-pressure seal 34 and the plunger 14. The space 58 functions as a so-called diffuser, and the jet flow from the high pressure seal 34 is decelerated and dispersed. In this embodiment, a guard 62 is provided between the first space 58 and the low-pressure seal 36 in order to further prevent the flow that reaches the low-pressure seal 36 from among the decelerated jet flow.

  The guard 62 is formed of a substantially truncated cone-shaped annular body made of a hard material such as metal. An outward flange (maximum diameter portion) 64 is formed at the end of the guard 62 on the large diameter side, and the outer diameter of the flange 64 is substantially the same as the inner diameter of the enlarged diameter portion 46. The flange 64 is sandwiched between an inward annular protrusion 66 formed on the inner peripheral surface of the cylinder 12 and the low pressure seal 36, whereby the guard 62 is fixed. In the fixed state, the end (minimum diameter portion) 68 on the small diameter side of the guard 62 is directed to the pump chamber 22. Further, the inner diameter of the end 68 on the small diameter side is larger than the outer diameter of the plunger 14, but is preferably made as small as possible within a range not contacting the plunger 14 when the pump is driven. By providing such a guard 62 in the cylinder 12, the annular second space 70 is formed in the cylinder 12 by the plunger 14, the low pressure seal 36 and the guard 62. The cross-sectional area of the second space portion 70 is larger than the cross-sectional area of the minimum gap between the minimum diameter portion 68 of the guard 62 and the plunger 14.

  In the illustrated embodiment, the inner diameter of the flange 64 of the guard 62 is substantially equal to the inner diameter of the lip portion (outer peripheral portion) 72 outside the low pressure seal 36. For this reason, even when the flange 64 is in contact with the low pressure seal 36, the inner lip portion 54 is not restrained, and the original sealing ability of the low pressure seal 36 is not impaired.

  Next, the operation of the plunger pump 10 configured as described above will be described.

  First, when a drive source (not shown) is activated and the crankshaft is rotated, the rotational force is transmitted through the connection rod, the plunger element, and the plunger rod 32, and the plunger 14 reciprocates in the cylinder 12. When the plunger 14 moves in the direction of the drive unit (the right direction in FIGS. 1 and 2), the inside of the pump chamber 22 is depressurized, and the suction valve 26 and the discharge valve 28 are opened and closed, respectively. Liquid is sucked into the pump chamber 22 through the suction valve 26. On the other hand, when the plunger 14 moves in the reverse direction, that is, in the direction of the pump chamber 22, the inside of the pump chamber 22 is pressurized, the suction valve 26 and the discharge valve 28 are closed and opened, respectively, and the liquid in the pump chamber 22 is discharged from the discharge valve 28. It is discharged to the discharge port 30 through. By repeating the suction process and the discharge process, the liquid is transported from the suction port 24 to the discharge port 30 in one direction.

  Since a liquid film is formed in the gap between the inner peripheral surface of the non-contact type high-pressure seal 34 and the outer peripheral surface of the plunger 14, the leakage of liquid from the pump chamber 22 to the drive unit side is greatly caused when the pump is driven. It is suppressed. However, in the discharge process, the inside of the pump chamber 22 is at a high pressure, so a part of the liquid flows through the minute gap between the plunger 14 and the high-pressure seal 34 to the drive unit side. This liquid flow becomes a high-speed jet, but is dispersed and decelerated by the diffuser effect of the first space 58 wider than the gap. In addition, since the liquid flowing in from the suction port 24 is also present in the first space portion 58, the velocity of the jet flow is also reduced by this.

  A portion of the jet is directed to the low pressure seal 36, but most of it is blocked by the guard 62. A part of the speed is increased through the gap between the small-diameter side end 68 of the guard 62 and the plunger 14, but this is also dispersed and decelerated due to the diffuser effect of the second space 70. Therefore, even if the liquid leaked from the high-pressure seal 34 hits the end face of the low-pressure seal 36, the collision energy is extremely small, the low-pressure seal 36 is not adversely affected, and the life of the low-pressure seal 36 is extended. Of course, it is possible to effectively prevent liquid leakage from the low pressure seal 36 to the drive unit side, so that the performance of the pump itself can be maintained over a long period of time.

  Such an effect can be similarly achieved even when the internal diameter of the high-pressure seal 34 is made larger than that of the prior art and the amount of liquid leakage is increased. That is, in the prior art, in order to reduce damage to the low-pressure seal 36, the inner diameter of the high-pressure seal 34 was made as small as possible to reduce the amount of liquid leakage. Can be increased within a range that does not impair the function as a seal. As a result, since the dimensional accuracy of the high-pressure seal 34 can be lowered, its manufacture becomes easy and the cost can be reduced. Even if the dimensional accuracy is low, the error can be absorbed because the seal member 44 is provided. In addition, contact between the plunger 14 and the high-pressure seal 34 can be prevented, and contamination of foreign matter due to wear into the transport liquid can be prevented. This is particularly effective in a high-pressure pump for ultrapure water.

  FIG. 3 is an enlarged cross-sectional view similar to FIG. 2, showing a second embodiment of the plunger pump according to the present invention. The second embodiment is different from the first embodiment described above in that an independent part guard is not provided, but the other points are substantially the same as the first embodiment. Corresponding portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the plunger pump 10 according to the second embodiment, instead of the guard 62 in the first embodiment, a portion corresponding to the guard 62 is integrally formed on the inner peripheral surface of the cylinder 12 in the first manifold 18. It is a feature. That is, on the inner peripheral surface of the cylinder 12, an annular projecting portion 162 as a guard is integrally formed in a region between the enlarged diameter portion 46 of the cylinder 12 to which the low pressure seal 36 is fitted and the first space portion 58. Is formed. The minimum inner diameter of the annular projecting portion 162 is slightly larger than the outer diameter of the plunger 14 and is substantially the same as the inner diameter of the small-diameter side end portion 68 of the guard 62 in the first embodiment. Further, the inner diameter of the annular projecting portion 162 is gradually enlarged from the minimum inner diameter portion in the direction of the low pressure seal 36, and a second space portion 70 is formed at this portion. In the portion adjacent to the low pressure seal 36, the inner peripheral surface of the annular projecting portion 162 is cylindrical, and the inner diameter thereof is substantially the same as the inner diameter of the outer lip portion 72 of the low pressure seal 36.

  The annular projecting portion 162 has a function as a portion in which the minimum diameter portion prevents leakage flow from the high pressure seal, and the second space portion 70 is formed in a portion adjacent to the low pressure seal 36. The diffuser effect can be produced. Therefore, it has the same effect as the guard 62 in the first embodiment described above. Further, in the plunger pump 10 according to the second embodiment, since the guard 62 is not necessary, the number of parts is reduced, and there is an effect that assembly / disassembly is facilitated.

  As mentioned above, although preferred embodiment of this invention was described in detail, it cannot be overemphasized that this invention is not limited to the said embodiment.

  For example, in the above embodiment, the shape of the inner peripheral surface of the guard 62 or the annular protrusion 162 is substantially conical, but the portion that blocks the flow to the low pressure seal 36 and the portion and the low pressure seal 36 If the space part 70 which exhibits a diffuser effect is formed between, the shape of the inner peripheral surface will not be specifically limited.

It is a longitudinal section showing partially a 1st embodiment of a plunger pump by the present invention. It is sectional drawing which expands and shows the A section of FIG. It is an expanded sectional view similar to FIG. 2 which shows 2nd Embodiment of the plunger pump by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Plunger pump, 12 ... Cylinder, 14 ... Plunger, 18, 20 ... Manifold, 22 ... Pump chamber, 34 ... High pressure seal, 36 ... Low pressure seal, 44 ... Seal member,
58 ... first space part, 62 ... guard, 64 ... flange (maximum diameter part), 68 ... small diameter side end part (minimum diameter part), 70 ... second space part, 72 ... outer lip part (low pressure seal) (Outer peripheral part), 162... Annular protrusion (guard).

Claims (4)

A cylinder (12);
A plunger (14) disposed reciprocally in the cylinder (12);
A drive for driving the plunger (14);
A pump chamber (22) disposed on the opposite side of the drive unit and communicating with the interior of the cylinder (12);
A non-contact type high pressure seal (34) disposed on the inner peripheral surface of the cylinder (12) on the pump chamber (22) side;
A contact-type low-pressure seal (36) disposed on the inner peripheral surface of the cylinder (12) on the drive unit side;
Provided between the high pressure seal (34) and the low pressure seal (36) in order to prevent a jet of liquid from between the high pressure seal (34) and the plunger (14) toward the low pressure seal (36). Guard (62, 162),
A first cross section formed between the high pressure seal (34) and the guard (62, 162) and having a cross sectional area larger than a cross sectional area of a minimum gap between the high pressure seal (34) and the plunger (14). 1 space (58);
Formed between the guard (62, 162) and the low pressure seal (36) and having a cross sectional area larger than the cross sectional area of the minimum gap between the guard (62, 162) and the plunger (14). A second space (70);
A plunger pump comprising:   The guard (62) is an annular body having one end having a maximum diameter portion (64) and the other end side having a minimum diameter portion (68), and the maximum diameter portion (64) is the low pressure portion. 2. The plunger pump according to claim 1, wherein the plunger pump contacts only an outer peripheral portion of one end of the seal (36), and the minimum diameter portion (68) is directed toward the high-pressure seal (34).   The plunger pump according to claim 1, wherein the guard (162) is integrally formed on an inner peripheral surface of the cylinder (12).   The plunger pump according to any one of claims 1 to 3, further comprising a seal member (44) made of an elastic material provided on an outer peripheral portion of the high-pressure seal (34).

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