DK165706B - FLUIDUM DEVICE WITH ROTATING WINGS AND WITHOUT ANY INTERNAL PACKAGING - Google Patents

Abstract

The invention relates to a fluid-operated rotary-vane device (actuator or pump), comprising a casing (3) traversed by a rotary shaft (1). A double vane (6, 6'), capable of rotating with the shaft, and two fixed partitions (5, 5') determine inside the casing two chambers (4a1, 2, 4b1, 2) of a complementarily variable volume. The vane is formed by a parallelepipedal bar attached to the shaft (1), which shaft is entirely cylindrical. The partitions (5, 5') are integral with a cover plate belonging to the casing. A very low level of inter-chamber leakage is maintained without an internal seal. <IMAGE>

Description

in

DK 165706B

The invention relates to a fluid apparatus of the type specified in the preamble of claim 1. Apparatus of this type are known, and are useful especially as rotary actuators, and the wing and partition are provided with respective sealing gaskets to prevent fluid (gas or hydraulic fluid) leakage between the chambers.

The presence of such inner sealing gaskets gives rise to several drawbacks: They are subject to wear and spring, therefore, the performance of the apparatus diminishes over time while contaminating the fluid used. In addition, they are specially shaped parts which are complicated to assemble and inspect and which are expensive.

From EP-A No. 0065588 is known a hydraulic rotary motor which is formed without sealing means in accordance with the aforementioned apparatus. This hydraulic motor, which is of a relatively complicated construction and is relatively expensive to manufacture, does not allow for the control of the leakage rates because its construction is incompatible with a sufficiently precise manufacturing method. Between the chambers are partitions which cannot be guaranteed a complete accurate position, which is why short and unstable leakage paths occur. It is only because of the viscosity of the oil used to make the engine work that the leaks are held down or even removed so that the sealing means can be avoided.

It is important, as far as possible, to eliminate any fluid leakage between the chambers which necessarily reduces the precision and hydraulic stiffness of the apparatus. Therefore, the phenomenon of internal leakage must be brought under control to limit its size and reduce the dispersion in a number of appliances.

The object of the invention is to improve a fluid apparatus of the type in question in such a way that, despite the omission of all internal gaskets, it is possible to maintain

DK 165706B

2 shows the relative amount of leakage between the chambers at a very low and very limited level in connection with the use of a liquid or gaseous fluid, in particular due to the introduction of very precise clearance between the various quantities of the apparatus and the formation of as long as possible leakage paths.

This is achieved by the fact that the apparatus mentioned at the outset is peculiar to the features specified in claim 1.

10 In the assembled apparatus, the wing and partition ensure that negligible fluid leaks are obtained from one chamber to the other in the annular space without the use of sealing means.

By using a shaft and a blade made up of two separate parts, it is possible to make the shaft with a highly accurate rotational cylindrical surface, which is not possible if the shaft and the blade are made of a single piece. Furthermore, this two-part construction means that the edges of the inward angles appearing between the surface of the shaft and the two sides of the blade extending perpendicular to the axis of the shaft can be given exact geometric shapes, while an inward angle cannot be machined exactly in a single piece. As a result, it has been observed that leaks located at the connecting edges or at discontinuities between the surfaces of the components of a rotary vane apparatus are the most difficult leaks to control. By producing the shaft and the wing as two parts to be assembled, while simplifying the shapes of these two parts, the danger of local leaks is limited.

In an apparatus in which the first annular surface of the end plate is set relative to its second annular surface, these two surfaces being interconnected by means of a circular cylindrical shoulder, over which the first bore of the body fits exactly, particularly accurately is obtained. positioning between the body and the end plate. In addition, it implies that the inward angle which is located at the root end

DK 165706B

3 of the partition, located at a distance from the chambers, the influence of any leaks that could occur at this location is significantly reduced.

The fact that the shaft, or at least the portion of the shaft extending within the housing and through bores passing through the housing shaft, has a cylindrical lateral surface of the same diameter throughout, implies a simple shape which helps to eliminate leaks or their effect between the chambers.

10

According to the invention, suitably the side surface of the shaft as well as the side surfaces of the blade, which are positioned opposite with very small clearance, and the base surfaces and the outer cylindrical surface of the annular space, may have a thin layer of an anti-stick coating.

According to the invention, the shaft should be guided in the housing of the apparatus by means of a pair of bearings suitable for ensuring that a rotating part is accurately positioned. It can for example. be: 20 Smooth bearings, ball bearings having no radial blur, hydrostatic bearings or passive or active magnetic bearings, the latter types of bearings being capable of imparting both shaft and radial control.

Accordingly, when the apparatus according to a known construction which is suitable for its geometry comprises a second wing and a second partition identical to the above wing and partition and diametrically opposite to each other, each chamber is thus divided in two diametrically opposite spaces with respective communication channels provided therebetween through the shaft, the two wings of the invention may be formed by opposite ends of said rod passing all the way through the shaft while the other partition is formed and arranged in the same manner as the first partition wall. The rod may either be attached to the shaft by means of a centering member, or it may be slidably mounted in the shaft.

DK 165706B

4

The blade or both blades in the apparatus may be made of a composite material. It is also possible to manufacture the component parts of the apparatus from the same material, thereby allowing for the possibility of operation over a large temperature range.

5

By means of the special construction and highly simplified geometric shapes with respect to its active surfaces, the apparatus according to the invention need not have any inner sealing gasket since the leaks between the chambers remain very small. As a result, it works without friction and without wear and tear of its component parts, providing excellent linearity and remarkable precision, as well as achieving very long service life with particularly stable performance. This is the reason why the apparatus is particularly suitable for use as a high-quality positioning power steering device.

Embodiments of the invention are described below with reference to the drawing, in which: FIG. Figures 1 and 2 show schematic cross sections through fluid apparatus having a rotating vane and two rotating vanes respectively; 3 it in fig. Fig. 2 shows apparatus adapted for use as a pumping apparatus; 4 is a section through an embodiment of an apparatus according to the invention, cut in section along the line IV-IV in FIG. 5, 30 FIG. 5 shows an axial section along the line V-V in FIG. 4, FIG. 6 shows the main component parts of the embodiment of FIG. 4 and 5 are perspective views of the individual parts removed from one another prior to assembly, and FIG. 7 is a perspective view of some of the FIG.

6 after the assembly thereof.

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5

FIG. 1 shows a fluid apparatus of the present type with rotary vane. It comprises an axis 1 arranged to rotate about its axis 2 within a coaxial cylindrical housing 3. Inside the housing there is an inner space 4 in the form of a circular 5 ring with a retangular cross section and limited by the lateral surface of the shaft 1. 1a, the surface of the inner bore 3a of the housing 3 and two planar annular surfaces centered on the axis 2 and belong to a pair of circular endplates not seen in the drawing. The annular space 4 is divided into two chambers 4a and 4b by means of a fixed partition 5 and by means of a movable vane 6 which rotates with the shaft 1. The chambers 4a and 4b are connected to an external pressure fluid circuit (hydraulic or pneumatic ) via openings 7a and 7b formed through the side wall of the housing 3. When pressurized fluid is supplied to the chamber 4a via the opening 7a and the opening 7b in the chamber 4b is connected to the discharge side of the external circuit, the shaft 1 is rotated in the direction indicated by an arrow with a rotation angle limited to approx. 280 °. The apparatus thus constitutes a rotary actuating device.

20 In the embodiment of FIG. 2, the shaft 1 has a second wing 6 ', the two wings 6 and 6' projecting from each end of a common diameter of the shaft. Similarly, a second partition 5 'is provided diametrically against the partition 5. Each 25 of the chambers 4a and 4b is thus divided into two diametrically opposite compartments or sections provided with the reference numerals 4al & 4a2 and 4bl & 4b2 respectively. , wherein the two sections of each chamber are connected to each other by a corresponding channel 8 or 9 running through the shaft 1.

This symmetrical arrangement balances the action of the fluid under pressure on the shaft, but at the expense of reducing the maximum rotation angle to approx. 100 °.

Both of the above apparatus can act as a motor (actuator) as mentioned in connection with the one shown in FIG. 1. Since the devices are reversible, they can also be used as receiving devices (pumps or compressors).

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6 sores). Eg. FIG. 3 is a double-acting pump circuit utilizing the embodiment of FIG. 2 shows two additional complementary openings 7'a and 7'b which open into the chamber sections 4a2 and 4bl. Each aperture 7a, 7b, 7'a and 7'b is connected to a check valve 10 which is mounted in the fluid circuit with such orientation that when the shaft 1 is subjected to a reciprocating rotary movement, a continuous suction action is provided at point A and continuous pump operation at point B in the fluid circuit.

10

An apparatus according to the invention, as described below with reference to Fig. 4 and the following figures, has the device shown in Figs. 2, which is immediately apparent from a comparison of FIG. 2 and 4. This apparatus comprises a stator having a housing 3 and two partitions 5 and 5 'and a rotor having a shaft 1 about an axis 2 and a pair of wings 6 and 6' which together with the two fixed partitions 5 and 5 'define two chambers, each split into two compartments or sections, which communicate with each other through the shaft via channels 8 and 9.

The chambers extend within the annular space of rectangular cross-section within the housing 3 coaxially around the axis 2 and are restricted externally by the bore 3a of the housing 3, internally by the side surface 1a of the shaft 1 and axially by two planar, annular surfaces 11 and 12, which belongs to the housing 3 (Fig. 5).

25

The pair of wings 6, 6 'is formed by a rod 13 of a retangular cross-section, the length of which is equal to the diameter of the bore 3a and whose ends are rounded corresponding to the radius of curvature of the bore. The bar is mounted in a space 14 extending centrally through the shaft 1 (Fig. 6), the dimensions of this compartment being well suited for accurately accommodating the bar 13 (Figs.

7). As shown in FIG. 5 and 6, the housing is formed of two parts which, after assembly, are symmetrical about the axis 2 of the shaft 1, one part being a body 15 which is bell-shaped, while the other part is an end plate 16 which closes the space within the body 5. Both the body 15 and the end surface 16 each have their central bores 17 and 18 respectively, which allow the shaft

DK 165706B

7 1 can pass through this. The body 15 has another larger diameter bore which constitutes the bore 3a defining the outside of the annular space which is within the housing around the shaft 1. Between these two bores 3a and 17 5 there is a plane annular shoulder 11 which forms one of the base faces defining the space in the axial direction, the other annular base surface 12 being on the end plate 16 around the bore 18. The annular base surface 12 is surrounded by a second planar annular surface 19 forming a joint -10 flange, and a flat annular surface 20 of the body 15 is pressed against it. In the planar annular face 19, holes 21 are formed which are arranged in a ring around the axis 2 and extend parallel thereto. These holes are arranged to receive bolts 22 which are screwed into cooperating 15 threaded holes 23 which are drilled into the annular surface 20 of the body 5. These bolts allow the body 15 to be joined to the end plate 16 so that the housing 3 is formed. In addition, an angular adjustment pin 24 protrudes from the surface 20. of this body 15. This pin is received in a corresponding hole 25 which is bored in the annular surface 19 of the end plate 16.

As can be seen more clearly in FIG. 6, the partitions 5 and 5 'are formed integrally with the end plate 16 where they are formed by projections projecting from the annular surface 12 parallel to the axis 2 with their radially inner surfaces 26 extending directly in extension of the surface. of the bore 18 through the end plate. In addition, the surface 12 is axially offset relative to the surface 19 such that the cylindrical skirt of the body 15 surrounding the bore 3a fits around the offset 30 surface 12 with the bore 3a being in tight fit around a circular cylindrical shoulder 26 located between the faces 12 and 19 due to the continued axial position. Under these circumstances, the radial outer surfaces 28 of the partitions 5 and 51 extend as direct extensions of the cylindrical surface of the shoulder 26.

The main operations required to produce the component parts described above are now explained in more detail. All

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8 parts are made of steel and have a common axis of symmetry which, when assembled, coincides with the main axis 2 of the apparatus.

A rod 13 is machined so that it has the desired retangular cross section axb to form the pair of wings 6 and 6 '(where a is the circumferential dimension and b is the axial dimension, i.e., the dimension parallel to the axis 2, around which the wings work after assembly). In the center of one of the sides of dimension a, a blind hole 29 is drilled and the length of the rod is formed slightly larger than the desired size, its end faces being machined to form a cylindrical surface about the same axis 2 as the hole. 29. The ends of the faces of dimension b are slightly milled 15 by 30, so that in the overall apparatus, sections 4al, 4a2, 4bl and 4b2 of the chambers have a minimum volume which is not zero when the pair of wings 6 and 6 'are at one of their end stroke positions (see Fig. 4).

The shaft 1 is formed in the form of a circular cylinder, and the space 14 is formed herein by electro erosion of the same dimensions a x b as the rod 3 forming the pair of wings 6 and 6 *.

The rod 13 is inserted into the space 14 through the shaft 1 and centered by a screw 31 which is engaged in a threaded hole 32 which is axially drilled axially from one of the ends of the shaft 1 and opens into the space 14 so that a non-threaded end 31a of the screw, the diameter of which corresponds to the diameter of the hole 29 in the rod 13, penetrates the hole 29 (Fig. 5).

After the rod 13 has been assembled, the surfaces are smoothed so that the axial dimension b becomes very accurate. Ten to 35 correspondingly, the cylindrical end faces are surface-treated so that they have the desired radius and so that they become exactly coaxial with the side surface 1a of the shaft 1.

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9

Thereafter, the end plate 16 is made of a thick disk, in which machining a central bore 18 of a diameter slightly larger than the diameter of the shaft is formed, after which the annular surface 19 is formed, and the two partitions 5 and 5 ' is formed by the remaining central ring by milling followed by radial grinding using a grinding wheel, the thickness of which is equal to the dimension a of the bar 13, ensuring that the ring has a remaining height c (Fig. 6) corresponding to the piece whereby the annular surface 12 10 must be axially offset leaving the partitions 5 and 51 projecting up to a height hj from this surface, where hj is very slightly larger than the dimension b of the rod 13.

The body 15 is made by making a bore 17 about the axis which will become the axis 2 of the final apparatus, the bore being identical to the bore 18 of the end plate 16, and these two bores serving as bearings for the cylindrical shaft 1. Then bore 3a is formed by machining and having a diameter slightly larger than the outside diameter of the ring 20 of the end plate, the partitions 5 and 5 'of which were made by machining together with the annular annular surface 12 so that the bore fits exactly around the shoulder 19, which limits the outside of the surface 12 and whose diameter is very slightly larger than the diameter between 25 the cylindrical ends of the rod 13. The two bores 17 and 3a communicate with each other via the annular shoulder 11, whose radial extension is the same as at the annular surface 12 of the end surface. The height h 2 of the bore 3a between the planes of the annular surfaces 12 and 20 is very slightly larger than the dimension b of the wings plus the depth of engagement c of the ring on the end plate 16 (Fig. 5).

The surfaces of the component parts of the apparatus which delimit the inner chambers are machined very accurately so that they are dimensioned within very small tolerances and so that they have an excellent surface condition. As a result, the spaces between the various parts can become very small, e.g. ca.

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10 5 μιη. Spi 1 the slots between the faces of the wings 6 and 6 'which extend perpendicular to the axis 2, and the annular faces 11 and 12, however, are slightly larger # ca. 10pm, to avoid any contact between the wings and the housing, although the shaft 1 is at a slight angle to the axis 2 due to the small clearance between the shaft and its bearings formed by the bores 17 and 18. All of these very small gaps (which have been greatly exaggerated in Figures 4 and 5 to make them visible) ensure that substantially no fluid leakage occurs from one chamber to another within the apparatus, although there is no sealing gasket between the wings and the housing, between the partitions and the housing or between the housing and the shaft. In contrast, there are external sealing gaskets. Between the body 15 and the end plate 16,. 15, sealing is secured by a sealing ring 33. This is accommodated in an annular groove 34 formed in the surface 20 at which the body abuts the end plate. Between the shaft 1 and the housing 3 there are also inserted two sealing rings 35 and 36 in annular grooves formed respectively in the bore ring 17 and the bore 18 (not shown in Fig. 6).

An apparatus such as that described above with reference to FIG. For example, 4-7 may have the following characteristics: 25 angle of rotation from plant to plant: 100 °, unit cylinder capacity: 1 to 500 cm3 / rad, available force pair 0.1 Nm rad / cm3 bar, 30 maximum feed pressure: 500 bar, hysteresis under load: < 0.1%, and 35 static accuracy: 10 ”6 rad / nm.

Claims (9)

A rotary vane fluid apparatus and for use either as a motor (rotary actuator) or as a receiving device (reciprocating pump), the apparatus comprising a fixed housing (3) having a shaft (1) extending therethrough and is pivotally mounted about its axis (2) and carries said wing (6), wherein the inner space 10 (4) of the housing (3) forms an annular rotational volume about the shaft (1) and has a radially plane cross-sections, which are tangular, limited by two planar annular base faces (11, 12) and two coaxial cylindrical faces (1a, 3a), respectively, forming an inner surface and an outer surface, which space (4) ) is divided into two chambers (4a, 4b) of complementary variable volume by a radial partition (5) fixed relative to the housing and by the wing (6) rotating with the shaft (1) and wherein the blade (6) is machined in such a way that it has a thickness (b) - seen in the axial direction of the shaft (1) - which, within a very small clearance, is equal to the distance {h2 ~ c) between the two planar annular surfaces (11, 12) defining the annular space (4) in this direction, and such a length and cylindrical shape at the ends, that its end surface, when the blade is mounted on the shaft (1), is placed on a rotational cylinder coaxial with the shaft (1) and which within a - a small clearance has the same radius as the radius of the cylindrical surface (3a) which defines the annular space (4) outwardly, and where the partition (5) is machined, such that it has a thickness (h ) - seen in the direction of the axis (2) - which, within a very small clearance, is equal to the distance (h2 ~ c) between the two annular surfaces (11, 12) mentioned above and such a cylindrical shape at its edges (27, 28) ), which radially abut the shaft (i) and housing (3), when the component parts of the apparatus remain t assembled, are located on rotation cylinders coaxial with the shaft (1), characterized in that the component parts of the apparatus are made of a single material, that the housing (1) is composed of a bell-shaped one the body (15) and an end plate (16) attached to the body (15) so that the fixed partition (5) is formed integrally with the end plate (16), the cylindrical edges (27) of the partition (5) 28) surfaces have radii which, within very small clearance, are equal to the radii of the inner and outer cylindrical surfaces (1a, 3a), respectively, which define the annular space (4) that the cylindrical lateral surface (1a) of the shaft (1) ) at least within the portion extending within the housing (3) and through bores (17, 18) provided in the housing (3) for passage of the shaft (1) having a constant diameter the wing (6) being formed by the end of a substantially parallelepiped-shaped rod (13) connected to the shaft (1) and received 15 e a compartment (14) formed herein, the side surface of the shaft (1) having been machined cylindrically before the blade has been mounted, so that the blade (6) and partition (7), when assembled, provide a small, predetermined and stable fluid leakage between the two chambers of the annular compartment (4) without the 1-20 addition of sealing gaskets, said end plate (16) comprising a first planar annular surface (12) coaxially disposed about a central bore (18) for passage of the shaft (1), forming the second base surface of one of the annular compartment (4), and from which extends the partition (5) radially bounded by surfaces (27, 28) whose radii are equal to each of the limiting radii of the first annular surface (12), that the first annular surface (12) is surrounded by a second planar annular surface (19) against which the body (15) rests after the apparatus is assembled, the body (15) and the end plate (16) in 30 overall condition has a common axis which coincides with the shaft axis (2), and that the first annular surface (12) of the end plate (16) is axially aligned with the second annular surface (19), the two annular surfaces being interconnected by a circular cylindrical shoulder (26), over which the bore (3a) of the body (15) which forms the outer cylindrical surface defining the annular space (4) fits exactly. DK 165706B 13 Apparatus according to claim 1, characterized in that it comprises a second wing (6 ') and a second partition (5') 'which is identical to the first-mentioned wing (6) and partition (5) and which are located diametrically opposite to these, whereby each 5 chambers (4a, 4b) is split into two diametrically opposite compartments or sections (4al, 4a2, 4bl, 4b2), between which communication channels (8, 9) are provided through the shaft and the two wings (6, 6 ') is formed by opposite ends of the rod (13) extending directly through the shaft (1), the second divider (5 *) being formed and positioned in the same manner as the first ski 1 (5) . Apparatus according to claim 2, characterized in that the rod (13) is fixed to the shaft (1) by means of a centering means (31). Apparatus according to claim 2, characterized in that the rod (13) is slidably mounted through the shaft (1). Apparatus according to one of claims 1 to 4, characterized in that the side surface (1a) of the shaft (1), as well as the surfaces of the blade (6), which are positioned opposite with very little clearance, and the base surfaces (11, 12) and the annular compartment (4) outer cylindrical surface (3a), has a thin layer of an anti-stick coating. Apparatus according to one of claims 1 to 5, characterized in that the shaft (1) is guided in the housing (3) by means of a pair of smooth bearings. 30 Apparatus according to one of claims 1-6, characterized in that the shaft (1) is guided in the housing (3) by means of a pair of ball bearings which have essentially no radial veil. Apparatus according to one of claims 1 to 5, characterized in that the shaft (1) is guided in the housing (3) by a pair of hydrostatic bearings. 14 DK 165706 B Apparatus according to one of claims 1-6, characterized in that the shaft (1) is guided in the housing (3) by a pair of passive or active magnetic bearings. 5 10 20 25 30 35