Reverse-running pump

[0001] This invention relates to mechanical engineering and may be used in high-pressure reversible pulseless pumps capable of operating both as motor and pump (hereafter referred to as pump). Gaseous and liquid working fluids are applicable.

[0002] The well-known high-pressure pulseless pump (RU 2123602) comprises housing with inlet and outlet ports, the rotor being mounted in the housing. Channels are provided in the rotor, wherein the slide valves are situated, which reciprocate along the rotor in an axial direction. Further, the general term displacer will be used instead of the slide valve. The pump comprises a mechanism being a plurality of members installed inside the housing, which sets an axial mutual position of the displacers in the channels of the rotor, a working chamber, a partition, which separates suction and injection spaces, thus preventing backstreaming of the working fluid between them. The partition is a special case of one of the insulating members, which insulating members imply any of the pump elements that prevent fluid leaking out of the pump cavities.

[0003] In this particular embodiment of the pump, from one side the working chamber is restricted along the axis of rotation of the rotor by the surface of one of the rotor's ends, which is in a sliding contact with the partition and which is hereafter referred to as the first end of the rotor, and from the other side, by a regulating member which is, in fact, an axially movable insulating member. In the radial direction the working chamber is restricted by the shaft surfaces and the inner surface of a hollow cylinder, which is mounted inside the housing and is not able to rotate with the rotor. The pump also comprises means connecting cavities at both sides behind the longitudinally opposite ends of the displacers.

[0004] In this particular embodiment of the pump, the means are implemented as a supporting and distributing member, which is mounted inside the housing and whose surface is in a sliding contact with the second end of the rotor. Furthermore, two disconnected cavities are provided in the said end of the supporting and distributing member, to which the channels in the rotor accommodating the displacers open. One of the cavities is connected by a channel with the inlet port, and another one—with the outlet port. The cavities are located so that one of the them is opposite the suction space and communicates via a channel with the inlet port; another one is opposite the injection space and is connected by a channel with the outlet port. Thus the cavities at both sides behind the longitudinally opposite ends of the displacers are connected, and thereby the displacer is balanced against the hydraulic forces of the working fluid, and the effect of the displacer volume on the stability of the flow and the capacity of the pump is avoided. One more widely known practical embodiment of said means may be an implementation of channels in each of the displacers so that the channels connect the cavities at both sides behind the longitudinally opposite ends of the displacers.

[0005] As the closest prior-art a high-pressure reversible pulseless pump (RU 2115807) was chosen, which, as in the above example, comprises housing with inlet and outlet ports, the rotor being mounted in the housing. The channels are provided in the rotor, accommodating the displacers, which are capable of reciprocating along the rotor's axis of rotation (longitudinally). The pump comprises a mechanism installed inside the housing, which sets a relative axial position of the displacers in the channels inside the rotor, a working chamber, a partition, which separates suction and injection spaces, thus preventing backstreaming of the working fluid between them. The partition is, in essence, a particular case of one of the insulating members, which members imply and will imply hereafter any of the pump members that prevents working fluid leaking out of the pump cavities. In this particular embodiment of the pump, from one side the working chamber is restricted in the axial direction by the end face of the rotor, which is in a sliding contact with the partition and is called here the first end of the rotor, and from the other side, by the inner surfaces of the housing facing this end of the rotor. In the radial direction, the working chamber is restricted by the surfaces of the shaft and inner surface of the housing. The pump also comprises means connecting the cavities at both sides behind the longitudinally opposite ends of the displacers. In this particular embodiment of the pump, the above means are implemented as the supporting and distributing member mounted inside the housing, whose end is in a sliding contact with the second end of the rotor. Furthermore, two disconnected cavities are provided in the said end of the supporting and distributing member, to which the channels in the rotor accommodating the displacers open. One of the cavities is connected by a channel with the inlet port, and another one—with the outlet port. They are located so that one of the cavities is opposite the suction space and communicates via a channel with the inlet port, and another one is opposite the injection area and is connected by a channel with the outlet port. Thus, the cavities at both sides behind the longitudinally opposite ends of the displacer are connected, and thereby the displacer is balanced against the hydraulic forces of the working fluid and the effect of the displacer volume on the stability of the flow and the capacity of the pump is ruled out. One more widely known practical embodiment of aforesaid means may be the implementation of channels in each of the displacers so that the channels connect the cavities at both sides behind the longitudinally opposite ends of the displacers.

[0006] It is an object of the invention to improve the operating parameters of such pumps and simplify the manufacturability.

[0007] These problems have been solved by a design of the pump, which comprises housing with inlet and outlet ports, a rotor with channels, wherein at least two displacers movable along the rotor axis of rotation (longitudinally), a working chamber, a partition, separating suction and injection spaces, insulating members, a member setting relative axial position of the displacers, and a mechanism connecting the cavities at both sides behind the longitudinally opposite ends of the displacers. According to the invention, the working chamber is formed by the surfaces of an annular slot, which is made in the end of the rotor so that its inner surfaces restrict the working chamber in the radial direction and are in a sliding contact with the surfaces of the partition. Furthermore, the displacers are located in the channels provided in the rotor. The channels are oriented longitudinally and extend in an axial direction, opening to the annular slot so that the prolongations of the said channels form recesses in the inner surfaces of the annular slot, which restricts the working chamber in the radial direction (i.e., normal to the axis of rotation of the rotor).

[0008] The abovementioned features included into the design of the pump provide technical results, which improve the operating parameters of the pumps of this type due to the damping effect, which appears when the displacers approach the insulating member that restricts the working chamber in axial direction. The damping effect prevents destruction and reduces wear of both the insulating member and the displacers being in contact with each other which enables the rotating speed of the pump to be increased.

[0009] Furthermore, the vibrations of the displacers caused by the hydraulic forces of the fluid in the working chamber are reduced; the noise generated by the displacers is also reduced and it becomes possible to reduce the consumption of materials, making the displacers less elastic and having lower bending strength for the same working pressure. One more useful result is the reduction of internal fluid backstreaming in the working chamber and the improvement of the conditions for the formation of the oil-film wedge between the surfaces of the partition and the annular slot.

[0010] Moreover, due to the radial restriction of the working chamber by the surfaces of the annular slot, provided in the end of the rotor, the rotor is relieved from the radial forces of the working fluid (unlike that in other types of pumps, e.g. vane pumps, in which the double-acting pump operation has to be used to this effect). Consequently, radial vibrations of the rotor and the noise arising thereby, as well as the fluid friction on the walls restricting the working chamber in the radial direction, are reduced.

[0011] All the aforementioned features implemented in the pump's design result in an increase of the efficiency and the service life of the pump, making it possible to use self-tightening end seals and to simplify manufacturing technology with specified tolerances and sizes. This also leads to essential enhancement of the resistance to hydraulic hammer and abrupt pressure jumps.

[0012] In common with the other types of pumps, this pump may have a multi-chamber design with several working cycles of the displacers per one rotor revolution and also may have a number of annular slots on both sides of the rotor ends accomodating the working chambers which may properly communicate with each other according to the pump operating conditions.

[0013] The entity of the invention is apparently described by the accompanying drawings in the following figures:

[0014]
FIG. 1 depicts a longitudinal sectional view of the pump

[0015]
FIG. 2 depicts a cutaway perspective view of the rotor showing a displacer and a push rod.

[0016] The pump (FIG. 1) comprises housing 1 with end plates 2 and 3. Rotor 5 is mounted inside housing 1 on shaft 4. Channels 6 are provided in the rotor 5, wherein the axially movable displacers 7 are located. The pump may comprise at least two and more displacers 7. Annular cylindrical slot (18 in FIG. 2) is provided in the end of rotor 5, which is located opposite the end plate 2. Channels 6 accommodating displacers 7 are made in rotor 5 so that they open to annular cylindrical slot 18 and form recesses 8 in its inner cylindrical surfaces. In other words, annular slot 18 is provided in the end of rotor 5 so that it passes through channels 6 in rotor 5, wherein displacers 7 are located, the radial width of annular cylindrical slot 18 being less than that of displacers 7. In the drawings of the present embodiment of the pump, channels 6 reach the end of rotor 5 and form recesses 8 in the inner cylindrical surfaces of annular slot 18 throughout its depth. However, in other embodiments of the pump, channels 6 may not reach the end of rotor 5 at some distance.

[0017] The pump comprises partition 9, which separates the injection and suction spaces. (The suction space is connected with the inlet port and the injection space is connected with the port; these are not shown for the simplicity's sake). The surfaces of partition 9 are in a sliding contact with the inner surfaces of annular cylindrical slot 18. Partition 9 is mounted on end plate 2 and may form a whole with the end plate. (In some embodiments of the pump, partition 9 may be fixed, being axially movable, and may interact with the means which clamp the partition to rotor 5). Therefore, the working chamber is restricted by the inner surfaces of annular slot 18 and the inner surface of end plate 2.

[0018] The pump comprises a mechanism setting displacers 7 in relative axial position in channels 6 of rotor 5. In this embodiment of the pump, the mechanism is made as a closed cam slot 10 in the inner cylindrical surface of housing 1. Furthermore, each displacer 7 is equipped with push rod 11, which enters in a sliding contact with cam slot 10Cam slot 10 is made so that displacers 7 located opposite the end of partition 9, are moved into rotor 5 at an equal distance, and a part of displacers 7 at a distance from partition 9 is pulled out of rotor 5 and is in a sliding contact with the inner surface of end plate 2.

[0019] The pump also comprises means connecting the cavities at both sides behind the longitudinally opposite ends of displacers 7. In this particular embodiment of the pump, the means are implemented as a set of channels provided in each displacer 7 in such a way that said channels connect the cavities at both sides behind the longitudinally opposite ends of the displacers 7. The above-mentioned channels are not shown on the drawing for simplicity. However, in general, the means connecting the cavities at both sides behind the longitudinally opposite ends of displacers 7, may be implemented in a variety of ways as well, for example, using a supporting and distributing disk, which is described in the closest prior-art of the invention (or using a plurality of said means). This supporting and distributing disk may be installed to be movable along the longitudinal direction of rotor 5.

[0020] Furthermore, the pump is designed so that the surfaces of the end of rotor 5, wherein annular cylindrical slot 18 is provided, which are located at different sides of annular cylindrical slot 18, are in a sliding contact with the opposite end faces of seals 12, which are located on the inner surface of end plate 2 and may be integral with it. This makes it possible to reduce fluid leaking out of the working chamber, because the working chamber becomes sealed over the end faces, and to reduce wear of the partition end face, which is in a sliding contact with the rotor, due to an enlargement of the contact area between the rotor and insulating members of the pump.

[0021] In this embodiment of the pump, seals 12 are implemented as two hollow cylinders, mounted in annular slots 13, which are made concentric in the inner wall of end plate 2. These hollow cylinders are mounted so that their cylindrical surfaces facing each other are in a contact with the surfaces of partition 9, which are located outside of annular cylindrical slot (18 in FIG. 2) made in the end face of rotor 5.

[0022] This substantially simplifies the manufacturability of partition 9 and its mounting guides (especially, in the embodiment with an axially movable partition and with a variable displacement).

[0023] The hollow cylinders are mounted in annular slots 13 and are movable along the axial direction of rotor 5. This enables the hollow cylinders to follow the axial movement of rotor 5 (if the pump is equipped with proper means for the axial movement of the cylinders), being permanently in contact with it. This consequently enables stable sealing of the working chamber to be obtained during vibrations and the axial shifts of the rotor, and the thermal expansion and wear caused by friction of the pump components to be compensated. The means of the axial cylinder movement are implemented as follows: at least one pass-through channel 14 is made in these hollow cylinders, which extends from the cylinder end facing the rotor up to annular slot 13, wherein the cylinder is mounted. By varying the cross-sectional area and the position of channels 14 at the cylinder ends, the optimal force clamping said cylinders to rotor 5 can be chosen, thus optimizing the backlash and leaking, thereby reducing the friction wear of the contacting surfaces.

[0024] The second end of rotor 5 is in contact with end plate 3. Slot 15 is made in the inner surface of end plate 3, wherein at least one seal 16 movable along the axis of rotor 5 is mounted. In this particular embodiment of the pump, two seals 16 are mounted in end plate 3, both having pass-through channel 17, which extends from the end of the seal 16 facing the end of rotor 5 up to annular slot 15, wherein seals 16 are located.

[0025]
FIG. 2 depicts a cutaway perspective view of rotor 5 with one displacer 7 and push rod 1 I to demonstrate annular slot 18 and recesses 8 on the inner surface of the rotor.

[0026] The pump operates as follows.

[0027] After starting the pump, while rotor 5 is rotating, push rods 11 start to slide within closed cam slot 10 and to reciprocate along the axis of rotation of rotor 5, thereby moving displacers 7. Cam slot 10 is made so that the movement of displacers 7 per one revolution of rotor 5 is characterized by the following cycle: displacer 7, which is opposite the end of partition 9, is pulled into rotor 5 and does not move along its axis of rotation. As displacer 7 moves away from partition 9, it starts being drawn out of channel 6 in rotor 5 to the cylindrical annular slot's cavity 18, and then sliding along the surfaces of recesses 8 (which are the additional guides for the displacer), and then, at some instant displacer 7 touches the inner surface of end plate 2. After that, displacer 7 slides with its end along the inner surface of end plate 2 without axial movement relative to rotor 5. As displacer 7 approaches partition 9, it starts being gradually pushed into rotor 5, until it passes partition 9 being pushed into rotor 5 up to the end. While sliding on the inner surface of end plate 2, displacer 7 separates the injection and suction spaces in the cylindrical annular slot 18.

[0028] In a general embodiment of the pump, a segment of end plate 2 over which displacers 7 slide may be implemented as an axially movable insulating member (variable displacement pump embodiment).

[0029] The working fluid, confined between two neighboring displacers 7and also found in channels 6, wherein the displacers 7 are located, starts to be transported from the suction to the injection space, wherein the low and high working pressure areas are produced, which are respectively connected with the inlet and outlet ports (the process is described in more detail the prior art patent).

[0030] The working fluid tends to stream through the backlashes between the insulating members from the injection to the suction space. In cylindrical annular slot 18the injection space is separated from the suction space by partition 9 and displacer 7 whose end is in a sliding contact with the inner surface of end plate 2.

[0031] The pressure of the working fluid, which is in the injection space, tends to move a part of displacer 7 pulled into cylindrical annular slot 18 towards the suction space, thus tending to bend and deform said displacer 7. However, recesses 8 accomodating the part of displacer 7 pulled into cylindrical annular slot 18 prevent the deformation and bending of displacer 7.

[0032] Recesses 8 act as additional guides for displacers 7, preventing bending and vibration of displacers 7 by the fluid pressure in the working chamber (with especial strength the effect is exhibited in the embodiment with cylindrical displacers 7). Accordingly, aforementioned effect reduces the noise generated by displacers 7 and enables the manufacture of displacers 7with lower material consumption, shorter in length, less elastic and stiff, for the same working pressure. Furthermore, it allows reducing the dimensions and the weight of the pump in comparison with the prior-art.

[0033] On more useful result of the presence of recesses 8 in the inner surfaces of cylindrical annular slot 18 is the reduction of the backstreaming and the relaxed requirements for the tolerance of displacers 7 for fitting the shape of channels 6; displacers 7 are clamped to the surfaces of recesses 8 by the fluid pressure, thereby providing better sealing between the surfaces of displacers 7 and recesses 8. Furthermore, since the fluid passes through the segments with different cross-sectional areas, the sealing produced by partition 9 between the suction and injection spaces is improved as well as for the oil-film wedge formation between surfaces of partition 9 and annular slot 18 accommodating partition 9.

[0034] Besides, due to the radial restriction of the working chamber by the surfaces of annular slot 18, provided in the end face of rotor 5, rotor 5 is relieved from the radial forces of the working fluid (in contrast to many other kinds of pumps, e.g. vane pumps, in which the double-acting pump operation is used to this effect). Consequently, radial vibrations of the rotor, and the noise and instability of the rotation of rotor 5 arising thereby, as well as the fluid friction on the walls restricting the working chamber in the radial direction and losses due to the friction of displacers 7 on these walls, are reduced.

[0035] Recesses 8 on the surfaces of cylindrical annular slot 18 produce the damping effect and allow it to be controlled (which is adjusted by selecting appropriate dimensions and a depth of recesses 8). The damping effect is observed while displacers 7 approach the inner surface of end plate 2restricting the working chamber in the axial direction. The damping effect arises due to prevailing backstreaming of the working fluid along recesses 8 (while they are connected with the low-pressure areas in the pumping chamber) from the high-pressure areas in the pumping chamber, while the displacer approaches the inner surface of end plate 2 and shuts aforementioned recesses 8. At that moment, the working fluid is compressed and tends to move displacer 7 away, thereby preventing its end from an abrupt impact on the inner surface of end plate 2. (This effect is exhibited especially strongly in the embodiment of the pump, in which displacers 7 are provided with the protrusions at their ends (not shown for the simplicity's sake), facing end plate 2 and located in the recesses. In this case, the protrusions primarily shut recess 8, producing a closed space inside it; hence the damping effect depends on the dimensions and shape of the protrusions).

[0036] The damping effect prevents destruction and reduces wear of both the inner surface of end plate 2 and displacers 7 which are in a contact with the end plate; this allows the rotating speed of the pump rotor 5 to be increased.

[0037] Seals 12 are implemented as two hollow cylinders, mounted in annular slots 13 and axially movable along the axis of rotor 5, following possible axial shifts of rotor 5, being permanently clamped to the rotor. The clamping is due to the fact that the working fluid, flowing from the injection space of the pump into the backlash under the end faces of seals 12 clamped to rotor 5, tends to force out seals 12 from the rotor. In this case, the working fluid flows under pressure from the backlash, through channels 14, into annular slots 13, thus balancing the fluid pressure in channel 14 and annular slot 13. Since the whole area of seal 12 is under the working fluid pressure from annular slot 13, whereas from the rotor side the pressure acts near the injection space of the pump only, the optimal force, clamping the rotor 5 to seals 12 implemented as cylinders, is obtained by a proper selection of the cross-sectional area and the location of channels 14 at the ends of seals 12. Furthermore, by connecting annular slots 13 with a throttle (not shown on the drawings for the simplicity's sake) and by adjusting the working fluid flow through the throttle, it is possible to optimize the backlash between seals 12 and end faces of rotor 5 contacting with them.

[0038] The operation of seals 16 is similar to that of seals 12.

[0039] It should be noted, that the pump is generally manufactured so that all the members, contacting with end faces of rotor 5 (as well as partition 9) may be designed axially movable and comprising means of self-tightening to the end faces of rotor 5, similar to the means of the axial movement of seals 12.

[0040] It should be also clarified that the rotation of the rotor is always referenced relative to the housing of the pump, no matter on which device the housing may be mounted to provide rotation of the rotor relative to the housing. In many practical cases of the pump usage, the pump's member referred to as housing may be mounted on the rotating shaft of the given device, whereas the pump's member called the rotor may be mounted on a frame or other rotating shaft of the same device.

Reverse-running pump

Information

Publication Number

Date Filed

Date Published

Inventors

CPC

US Classifications

International Classifications

Abstract

Description

Claims

Priority Claims (1)

PCT Information