Rotary expander

Abstract

Disclosed herein is an improved expander of the type of the type that is used to extract power from a supply of pressurized fluid and that includes: a housing: having a rotation axis; defining a hollow interior having an annular surface orientated parallel to the rotation axis and through which the rotation axis extends; and defining one or more ports which extend through the housing to the interior; a rotor mounted in the housing for rotation about the rotation axis, the rotor having a body having an outer tubular surface, the tubular surface having defined therein a plurality of voids; for each of the voids of the plurality, a vane, the vane: having a seal defining a tip of the vane; being mounted in the void for which it is provided for movement between a retracted position and an extended position; and being adapted such that, upon rotation of the rotor in the housing, movement of the vane between the extended and retracted positions causes the tip seal to sweep the annular surface; control means for controlling movement of the vanes and access to the ports such that the vanes create chambers which increase in volume when in communication with the source of pressurized fluid, the improvement comprising: the rotor having a cylindrical outer surface essentially interrupted only by an elongate aperture for each vane and through which said vane reciprocates.

Description

ROTARY EXPANDERFIELD

[0001] The invention relates to the field of rotary expanders.BACKGROUND

[0002] Known rotary expanders are inefficient or relatively expensive to manufacture or maintain.SUMMARY OF THE INVENTION

[0003] One of the improvements is a rotor having a cylindrical outer surface essentially interrupted only by an elongate aperture for each vane and through which said vane reciprocates.

[0004] Another of the improvements is a vane mounted to the rotor for movement within a hollow and about a pivot axis, the vane being in the form of a circular arc, the center of the curve of the arc being coincident with the pivot axis.

[0005] Another of the improvements is a curved slot which terminates in the elongate aperture and which receives the vane in a sliding fit.

[0006] Another of the improvements is a reinforcement for each vane, each reinforcement spanning the hollow provided for said each vane to maintain the shape of the outer surface of the rotor.

[0007] Another of the improvements is a plate which defines the reinforcement, the plate being disposed in a hollow milled in the rotor and secured to the rotor by bolts.

[0008] Another of the improvements is a bore extending centrally through the rotor, a hollow recess defined in the rotor through which the bore extends, an annular collar having a channel communicating with the bore and a chambered flange seated in the hollow and mounted to the rotor by bolts, an o-ring captured between the flange and the rotor to seal the channel to the bore and an output shaft having a central portion and a shoulder, the central portion being sealingly received by the o-ring and occupying the bore and the channel in a transition fit and the shoulder abutting the rotor.

[0009] Advantages, features and characteristics of the present invention will become apparent upon review of the following description and drawings, the latter being briefly described hereinafter.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a perspective view of a prior art expander;

[0011] FIG. 2 is a view similar to FIG. 1 with a portion removed for clarity;

[0012] FIG. 3 is a view of the structure of FIG. 2 from another vantage point;

[0013] FIG. 4 is a view similar to FIG. 3 with a portion removed and partially exploded, for clarity;

[0014] FIG. 5 is a view of a portion of the structure of FIG. 3;

[0015] FIG. 6A is a cross sectional, partially schematic view of another prior art expander;

[0016] FIG. 6B is a view of the structure of FIG. 6A in another position;

[0017] FIG. 6C is view of the structure of FIG. 6A in yet another position;

[0018] FIG. 7 is a view similar to FIG. 6A showing another expander;

[0019] FIG. 8 is a view of another embodiment of the structure of encircled area 8 of FIG. 4;

[0020] FIG. 9 is a view similar to FIG. 6A of another prior art embodiment;

[0021] FIG. 10 is a perspective view of an expander according to an embodiment of the invention;

[0022] FIG. 10A is a view of the structure indicated by arrow 10A in FIG. 10;

[0023] FIG. 10B is a view of the structure indicated by arrow 10B in FIG. 10;

[0024] FIG. 10C is a view of the structure indicated by arrow 10C in FIG. 10;

[0025] FIG. 11 is a view, similar to encircled area 11 of FIG. 6A, of the structure of FIG. 10;

[0026] FIG. 11A is a view similar to FIG. 11, with a portion removed for clarity;

[0027] FIG. 12 is view, similar to FIG. 4, of the structure of FIG. 10;

[0028] FIG. 13 is a view, similar to FIG. 6A, of the structure of FIG. 10;

[0029] FIG. 14 is a cross-section of the structure of FIG. 10;

[0030] FIG. 15 is a view similar to FIG. 14; and

[0031] FIG. 16 is a view of the structure indicated by arrow 16 on FIG. 11A.DETAILED DESCRIPTION

[0032] The invention relates to improvements in the field of rotary expanders.

[0033] By way of background in this regard, a prior art expander 20 is illustrated in FIGS. 1-5 and will be understood to include a housing 22, a rotor 24, control means 26 and end seals 28.

[0034] The housing will be understood to: have a rotation axis R-R; define a hollow interior 30 having an annular [generally oval] surface 32 orientated parallel to the rotation axis and through which the rotation axis extends; define one or more ports 34 which extend through the housing to the interior; and be defined by a tubular block 36 disposed between a pair of end plates 37.

[0035] The rotor will be seen to be disposed in the interior and to include a body 38, a shaft 40 and vanes 42. This body will seen to be a generally cylindrical metal structure suitable for construction with wire EDM and drilling and to have a central bore 43 and an outer tubular surface 44, the tubular surface having defined therein a plurality of voids 46 and, associated with each void, a respective socket 48, each void being defined in part by an arcuate slot 50 and each socket defining a respective pivot axis P-P. The shaft passes through the bore. The vanes are provided one for each of the voids. Each vane has a seal 52 defining a tip of the vane, terminates in a pintle 54 which is mounted in the associated socket for rotational movement, as discussed further below, and includes an arcuate slider 56. Each vane further has vents 57 defined therein.

[0036] The control means will be seen to include springs 58.

[0037] The end seals are defined in part by body seals 60 carried by and spring mounted to the body and in part by vane seals 62 carried by and spring mounted to the vanes, all to project to and seal against the end plates. As best indicated by FIG. 4, the seals 60,62 in the exemplary embodiment are springmounted within slots provided in the vanes and body.

[0038] In use, it will be understood that the foregoing structure provides the functionality normally associated with an expander, namely, pressurized fluid is introduced into the interior through the ports, thus creating force on the trailing edges of the vanes which causes the rotor to turn.

[0039] The control means controls movement of the vanes and access to the ports such that the vanes create chambers which increase in volume when in communication with the source of fluid at high pressure.

[0040] The creation of a chamber that increases in volume when in communication with the source of pressurized fluid is best seen in the schematic views of the alternate expander of FIGS. 6A-6C, wherein a single vane is enumerated, for clarity, a chamber is seen to be created as the vane nears the port, as per the sequence of FIG. 6A, 6B, and the chamber C will be seen to increase in volume in the sequence of FIG. 6B, 6C.

[0041] FIG. 7 shows a variation on the geometry having a modified block 36' wherein the annular surface and the tubular surface are oval, with the rotor centered in the interior. An embodiment with a modified block 36' to achieve this is shown in FIG. 7. The modified block 36' shows that the number of ports can be adjusted routinely by persons of ordinary skill in the art.

[0042] As well, a large range of customized volumetric expansion ratios can be achieved using readily available metered inlet controls without altering the base design.

[0043] Moreover, whereas springs are shown to bias the movement of the vanes at low speeds and startup, this is not necessary: there are many viable ways to control the vane movement such as magnets 64 as shown in FIG. 8 which repel vanes 42 from the body 38. Compressed gas can be used, not shown.

[0044] Further, whereas in the foregoing embodiments, no lubrication is provided, such that the seals constitute sacrificial wear components, numerous lubricants can be employed including wet lubricants (oils) and dry lubricants (graphite, bronze, molybdenum disulfide, etc.) to increase life. Similarly, the end seals are not essential and could be removed in some applications.

[0045] As well, to reduce friction, wear and mechanical stress, axle-supported bearings can be provided at the ends of the sockets, not shown in FIG 8. Bearings can also be provided to facilitate movement of the sliders, as indicated by bearings 66 in FIG. 9. FIG. 9 also shows that the annular surface can be cylindrical, which has advantages in terms of machining.

[0046] Yet further, the expander can run in constant pressure mode like a hydraulic motor providing maximum torque at lowest speeds. This can be used as a safety fall-back, low expansion mode with full torque at low speed should the control means fail.

[0047] Turning now to the improvements, these are embodied in the expander 100 illustrated by way of example only in FIG. 10- FIG. 17. The expander 100 of FIG. 10-17 operates in a manner largely analogous to that of FIGS. 1-9 and thus, a detailed description of its operation is neither required nor provided: the following description details only aspects of the expander 100 that differ from the expander of FIGS. 1-9.

[0048] One of the improvements is a vane 102 mounted to a rotor 104 for movement within a hollow 106 and about a pivot axis 108, the vane being in the form of a circular arc, the center of the curve of the arc being coincident with the pivot axis, all as shown in FIG. 11 and FIG 11A. The vane will be understood to be mounted at one end to the rotor by a pivot roller 103 and to carry a further cam follower bearing assembly which provides cam followers 105 for traversing races 107 provided in the end plates 10A, 10C. Seals are provided at the tip 109 and ends 111, as seen in FIG. 16, which has advantage in terms of efficiency.

[0049] The rotor shown will be understood to be of a single piece type.

[0050] Another of the improvements is a cylindrical outer surface 110 of the rotor essentially interrupted only by an elongate aperture 112 for each vane and through which said vane reciprocates, as indicated, inter alia, in FIG. 12.

[0051] Another of the improvements is a curved slot 114 for each vane which terminates in the elongate aperture and which receives the vane in a sliding fit.

[0052] Another of the improvements is a reinforcement 116 for each vane, each reinforcement spanning the hollow provided for said each vane to maintain the shape of the outer surface of the rotor.

[0053] Another of the improvements is a plate which defines the reinforcement, the plate being disposed in a cavity 118, the cavity milled in the rotor, the plate secured to the rotor by bolts 120, as indicated in FIGS. 11 and 11A. The plate also minimizes axial vane travel to protect seals and prevent the vanes from scratching the endplates.

[0054] Another of the improvements is a bore 122 extending centrally through the rotor, a hollow recess 124 defined in the rotor through which the bore extends, an annular collar 126 having a channel 128 communicating with the bore and a chambered flange 130 seated in the hollow and mounted to the rotor by bolts 132, an o-ring 134 captured between the flange and the rotor to seal the channel to the bore and an output shaft 136 having a central portion 138 and a shoulder 140, the central portion being sealingly received by the o-ring and occupying the bore and the channel in a transition fit and the shoulder abutting the rotor, as indicated in FIG. 15

[0055] Yet another improvement is, for each end of the output shaft, an annular seal insert 142, the seal insert encircling the end of the output shaft for which it is provided and having an annular groove defined therein, the groove being in receipt of an O-ring 144 which seals the seal insert to the rotor, the seal insert having defined therein an annular channel, the annular channel in receipt of an annular shaft seal 146, the annular shaft seal encircling the end of the output shaft and receiving same for sealed, rotational movement. This is all shown in FIG. 14, which also illustrates that the shaft / rotor assembly is mounted to the end plates for rotational movement by means of tapered roller bearing assemblies, each having an outer bearing race 148 mounted to the end plates, an inner bearing race 150 mounted to the shaft and a roller bearing 152 captured therebetween.

[0056] Advantages of the foregoing include, without limitation:• the single piece rotor is relatively easy to manufacture• the hinged vanes withstand relatively high working pressures• forces from high working pressures are transmitted directly to the rotor through the hinges• the absence of rolling elements reduces stress• the reinforcement plates can be dry lubricated and of materials differing from the rotor• the reinforcement plate allows for the rotor itself to be less rigid, with commensurate impacts on cost• the removable output shaft is easily serviceable• there is no need to mill the rotor and shaft from a single piece of material, which would otherwise include waste• the locating flange is serviceable without requiring a new shaft• the seal insert centers the shaft seal during assembly, thereby to avoid the need to rely on critical machine tolerances

[0057] Whereas the above improvements are illustrated in a specific embodiment, variations are possible. Without limitation in this regard:• reinforcement ribs can be added to the back of the vanes, with clearances cut in the rotors, where higher pressures are required• the shaft can be made of materials differing from the rotor• the seal insert can be made out of heat dissipating materials such as aluminum or copper

[0058] Yet further variations are possible. Accordingly, the invention should be understood to be limited only by the accompanying claims, purposively construed.

Claims

CLAIMS1. An improved expander of the type of the type that is used to extract power from a supply of pressurized fluid and that includes: a housing: having a rotation axis; defining a hollow interior having an annular surface orientated parallel to the rotation axis and through which the rotation axis extends; and defining one or more ports which extend through the housing to the interior; a rotor mounted in the housing for rotation about the rotation axis, the rotor having a body having an outer tubular surface, the tubular surface having defined therein a plurality of voids; for each of the voids of the plurality, a vane, the vane: having a seal defining a tip of the vane; being mounted in the void for which it is provided for movement between a retracted position and an extended position; and being adapted such that, upon rotation of the rotor in the housing, movement of the vane between the extended and retracted positions causes the tip seal to sweep the annular surface; control means for controlling movement of the vanes and access to the ports such that the vanes create chambers which increase in volume when in communication with the source of pressurized fluid, the improvement comprising: the rotor having a cylindrical outer surface essentially interrupted only by an elongate aperture for each vane and through which said vane reciprocates.

2. The improved expander of claim 1, wherein each vane is mounted to the rotor for movement within a hollow and about a pivot axis, the vane being in the form of a circular arc, the center of the curve of the arc being coincident with the pivot axis.

3. The improved expander of claim 1, further comprising a curved slot for each vane which terminates in the elongate aperture and which receives said each vane in a sliding fit.

4. The improved expander of claim 2, wherein a reinforcement is provided for each vane, each reinforcement spanning the hollow provided for said each vane to maintain the shape of the outer surface of the rotor.

5. The improved expander of claim 4, wherein a plate defines the reinforcement, the plate being disposed in a hollow milled in the rotor and secured to the rotor by bolts.

6. The improved expander of claim 1, wherein: a bore extends centrally through the rotor; a hollow recess is defined in the rotor through which the bore extends; an annular collar has a channel communicating with the bore and a chambered flange seated in the hollow and mounted to the rotor by bolts; an o-ring is captured between the flange and the rotor to seal the channel to the bore; and an output shaft has a central portion and a shoulder, the central portion being sealingly received by the o-ring and occupying the bore and the channel in a transition fit and the shoulder abutting the rotor.