JPS63109294A - Vane pump - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vane pump, the cylindrical rotor of which has approximately one guide slit located in a plane containing the axis of the rotor for guiding the blades. For rigid blades, the casing cross section is constituted by a curve that is closed in itself, the secant of which intersects perpendicularly to the rotor axis and has a length approximately equal to the length of the blade. Regarding formal matters.

Prior Art This vane pump was published as a West German patent application No. 25.
No. 21190, No. 2235045, No. 24072
It is known from No. 93.

The vane pump according to DE 240 729.3 has substantially rigid vanes which have radially movable sealing edges at their edges;
This sealing edge contacts the casing circumferential wall. The casing cross section is described by a circle. In order to compensate for the eccentricity of the rotor relative to the casing, the sealing strips therefore travel a relatively large distance during rotation of the rotor.

This is disadvantageous in terms of wear on the seal strips and vanes. Moreover, the comparatively thin sealing strip protrudes so significantly beyond the vanes precisely in the discharge area that there is a risk of damage to the sealing strip or the guide flank of the vane.

Vane pumps are particularly unsuitable as vacuum pumps for brake force amplifiers in automobiles.

German Patent Application No. 2 235 045 Akira #l Homare shows a vane vacuum pump, the casing cross section of which consists of two semicircles, which are connected to each other by tangents at the top and bottom, respectively. combined.

This ensures that, despite the eccentric arrangement of the rotor, no gaps occur between the blades and the circumferential wall of the casing. However, with this shape of the casing, gaps cannot be avoided. This pump is also not suitable for generating a vacuum for brake force amplifiers in motor vehicles.

DE 25 23 190 A1 describes a vane pump of the type mentioned at the outset.

In this configuration, the guide slit is located in a plane containing the axis of the rotor, and the only blade is guided radially in this guide slit. The casing is configured as a Pascal spiral. The vanes themselves have sharp edges at the ends that contact the casing. The design of the vane pump with only one vane is geometrically possible due to the design of the casing cross-section as a Pascal spiral and the sharp configuration of the vane ends.

The disadvantage of this vane pump is that there is only a linear contact between the casing and the rotor in the region of bottom dead center, where the blade ends completely enter the rotor. With such a short sealing section, a non-contact between the delivery zone and the suction zone of the pump occurs in this region, which is accompanied by a corresponding deterioration of the volumetric efficiency. Furthermore, such vane pumps whose casing cross section is described by a Pascal spiral have the disadvantage that the displacement per revolution is limited. In this case, the ratio of the sum of the rotor radius and eccentricity to the eccentricity must be between 1.5 and 6. This ratio is 1.5
If it is smaller than , unstable blade motion will occur.

A ratio greater than 6 results in a very large casing, which does not offer any advantage in terms of available pump chamber for delivery.

Problem to be Solved by the Invention The object of the invention is to provide a vane pump housing with only one vane, which vane pump has a long service life, especially as a vacuum pump, and can be used at highly variable rotational speeds. , a good suction effect occurs even at low speeds, the pump has a high discharge capacity, and even at low speeds a sufficiently high vacuum is created after a few seconds, and the pump has low requirements with little wear. The idea is to configure it so that it has energy.

Means for Solving the Problems According to the invention, the above-mentioned problem is solved by firstly realizing that the casing cross-sectional shape described by Pascal's spiral or by two semicircles is only a geometrically constrained shape. However, this shape is extremely inconvenient in terms of its function as a pump, and from a geometrical point of view,
It is solved by the recognition that it can be replaced by an arbitrarily large group of curves satisfying Yasugi that the length of the curve perpendicularly intersecting the rotor m-line is approximately equal to the length of the blade. Starting from this recognition, the above problem can then be solved by means of: from a group of geometrically appropriate curves, the loads on the blade during radial blade movement, in particular acceleration loads, shock/impact loads and the blade end. The solution is that a curve is selected that ensures that the frictional force acting on the

The embodiment additionally or alternatively takes into account a good seal between the discharge zone and the suction zone of the pump in the region of bottom dead center and minimizes the pressing forces acting on the vanes in the direction perpendicular to the plane of the vanes. It may be necessary or advantageous to do so. According to an embodiment of the invention, this is achieved in addition to or instead of the above optimization by selecting a curve that fits the rotor in the region of bottom dead center. This area is designated as the seal area. It is advantageous if a curve is selected which has a radius of curvature smaller than 1/2 the length of the vane in the sealing region.

The minimum possible radius of curvature of the curve is approximately equal to the rotor radius. In this case, the center of the radius of curvature is also approximately the center of the rotor.

The adaptation of the housing to the rotor circumferential surface in the region of bottom dead center creates a sealing gap that extends over a certain length. The longer this gap and the narrower this gap, the better the sealing effect.

According to the invention, the length of the sealing area is preferably greater than the width of the guide slit. This ensures the sealing of the discharge zone with respect to the suction zone in such a way that the guide slit is located in the region of bottom dead center and the vane is lifted off the casing wall as a result of the maximum centrifugal force acting on this vane in the region of bottom dead center. Even if a gap is formed between the rotor and the casing wall, it is guaranteed that this will be done by the rotor circumferential surface.

The invention ensures a seal between the discharge zone and the suction zone in the region of bottom dead center. Such a seal cannot be obtained with other configurations of vane pumps, even with multi-blade vane pumps. The pump according to the invention can therefore be operated with very low amounts of lubricant or even as a dry-face sealed rotor.

Furthermore, the housing wall configured according to the invention makes it possible to keep the pressing forces acting on the blades in a direction perpendicular to the blade plane low. This is due to the fact that the length of the free vanes protruding from the rotor, especially in the discharge area, is smaller than in known vane pumps, whether single or multi-bladed.

Geometrically, this means that the curve describing the casing cross-section closely matches the rotor in the region of bottom dead center and is therefore shorter than in known vane pumps even in the discharge region located in front of bottom dead center. It has a secant distance from the rotor center.

Embodiment 1 A vane pump 1 shown in FIGS. 1 to 3 is fitted to a crank casing 2 of an automobile through a flange 13 and sealed with a seal member 14. A cylindrical rotor 5 is rotatably supported within the pump casing 4 . To this end, the pump casing (the cross-sectional shape of which will be described later) has an eccentric addition, which constitutes a bearing casing 37 . The bearing housing 31 projects into the crank housing and is supported in such a way that it is centered within the crank housing and comes into contact with the housing at a so-called dead center. It can be said that the bearing casing 37 constitutes a sliding bearing for the free end of the rotor 5. Therefore, axial miso is suggested. This miso is used to lubricate sliding bearings.

The rotor 5 is a tube with an equal outer diameter between both ends.

In the area of the casing, the tube has only one guide slit 6. The guide slit is located in a plane containing the axis and passes through the bore, and its length in one direction is strictly equal to the axial length of the pump casing 4. Inside the guide slit 6, only one blade 7 is slid into the guide slot 11). The width of the vane is equal to the axial length of the pump casing. The blade 4 can be manufactured from one piece. However, the vanes 4 can also be provided with sealing strips at their ends. The sealing strip is radially slidably but closely guided in the groove 9 of the wing 7. The exhaust hole 10 connects the bottom of the groove 9 with the front side of the blade when viewed in the direction of rotation.
The highest pressure prevailing in the pump is always present in the base 9, thereby ensuring that the sealing strip 8 is pressed outwards. In both cases, i.e. when the vane 9 is made in one piece, as schematically illustrated in FIG. Due to the shape of the casing cross section, which will be described later, it comes into close contact with the circumferential surface of the casing 4 at each rotational position.

In each case it is advantageous if the ends of the blades are rounded with radius r. This radius is chosen as large as possible and in any case larger than 1/2 of the thickness of the blade 7.

If the vane has a sealing strip, the sealing strip has a head outside the groove 9 which is significantly wider than the groove 9 but slightly narrower than the vane 7.

The radially movable sealing strip shown in FIG. 2 is used in particular to compensate for thermal expansion and wear.

The circumferential wall of the pump casing 4 is designed in such a way that it is a closed curve in itself, satisfying the geometrical requirement that all secant lines passing through the rotor center 0 have equal length, in which case the above-mentioned The length is approximately equal to the length L of the blade. This requirement also applies if the vanes have sharp edges, as shown in FIG. However, when the blades have a large radius of curvature as shown in FIG. 2, the circumferential wall of the pump casing has, in cross section, all secant lines passing through the rotor center 0 having the same length; In addition, an equidistant line is drawn with respect to a known curve that satisfies the geometrical Yasugi condition of being equal to the blade length L-2r.

This equidistant line is at a distance from the curve approximately equal to the radius of curvature r of the vane head.

Therefore, in order to design the cross section of a vane pump with a sharp blade head (FIG. 3), first the length L of the blade and the outer diameter R of the rotor 5 are determined. Blade length L and outer diameter R
The difference between the two is extremely important in determining the pump's discharge capacity. This difference is limited by strength and other considerations. The rotor is inside the casing, and this is the first sub-position.
That is, since it is supported in circumferential contact with the casing at the so-called bottom dead center, the blade 7 completely projects into the guide slit 6 of the rotor 5 at the bottom dead center, as shown in FIG.

Here, an appropriate curve shape for the range of bottom dead center is determined. In the configuration according to FIG. 3, it can be seen that between points C1 and pl, the casing peripheral wall draws a curve with a radius only slightly larger than the radius R of the rotor in cross section.

This results in a very narrow sealing gap in the region of bottom dead center, which sealing gap is several times as long as the width of the id slit in which the blades were guided as a secant. The curve forming the cross section of the casing is then continued in such a way that its radius of curvature increases first. The increase in the radius of curvature should occur as a continuous function depending on the angle of rotation of the rotor, and this function should have as few bends as possible. This achieves impact-free radial movement of the blades guided in the rotor slits with slight accelerations or decelerations. By this means it is possible to produce blades of relatively low strength, ie thin and light blades. However, wear is limited, especially on the heads of the vanes that rub against the peripheral wall of the casing.

Once the curve describing the cross-section of the casing wall for 1800 rotation angles of the rotor has been determined, the curves for the remaining rotation angles can be designed. Assume that the curve between points E1 and E2 is optimally determined in the form described above. In this case, points E1 and E2 are on the dividing line passing through the rotor center 0.

This dividing line has the length L of the blade. Now for example C7
Point C2 can be determined from point C1 by drawing a secant line having blade length L passing through rotor center 0 from . The same applies to other points such as A2.

In this curve design, only one bottom dead center point is allowed.
I understand. The dead center is defined as the point where the blades run completely into the rotor with their ends, so that the casing and the rotor circumferential surface contact. In the described configuration, contact takes place at each point in the section between points B and C, so that it can be referred to as a dead center region. This region is designated as a sealing region in the sense of the invention.

As already mentioned, it is advantageous if the head of the vane does not have a sharp edge, but has a sufficiently large rounded radius. The radius of this rounding must be at least equal to 1/2 the thickness of the blade. The invention provides an ideal solution between the head of the vane and the casing jacket if the vane is constructed with rounded ends and the casing jacket is constructed according to the following design: A gap-free seal is obtained: First, the self-closed curve K shown in FIG.
Designed based on the principles described in connection with The amount R (rotor radius) as the theoretical rotor radius Rth is equal to the actual rotor radius Rp minus the radius r of the roundness of the blade end.

Therefore, for the design of the curve according to FIG.
determined to suit.

The length of the secant to the curve is still equal to the scale, where L is equal to the maximum selected actual blade length LP minus twice the radius r of the roundness of the blade head. . The theoretical blade length Lth is given as a measure for the length of the secant line of the song MK. This theoretical blade length Lth U is then equal to the selected actual blade length LP minus twice the radius r of the roundness of the blade head.

That is, L=Lth=LP-2r holds true.

The circumferential wall G of the casing is then determined as an equidistant line to the curve K at a distance of the radius of curvature r of the blade head.

As schematically illustrated in FIG. 2, the Ponzo casing 4 is equipped with an inlet 11 and an outlet 12, with a check valve 31 inside the inlet and a check valve 24 inside the outlet. is located. The suction opening 11 is offset by approximately 90° relative to the dead center position, and the outlet 12 is located in the region in front of the bottom dead center in the direction of rotation indicated by the arrow 35.

As shown in FIG. 1, the large mouth valve 31 is configured as a mushroom-shaped valve. This is a mushroom-shaped rubber body, which is inserted into the porous valve plate in this shape, and is in close contact with the valve plate with the edge of the head, and when the valve Close the holes in the plate.

When air flows in, the head turns in the suction direction so that the suction port is released. In the opposite direction, the head is cut off.

As shown in FIG. 1, the outlet first has a groove 36 in the end face of the pump casing, so that the miso spreads over a larger outlet area. The outlet 12 penetrates the casing lid with this miso as a starting point. Exit 12
opens into the outlet chamber 25. The valve 24 is designed as a leaf spring valve, which is fixed on one side and covers the outlet opening in the outlet chamber 25 . The outlet chamber contains the valve 24 and the bearing casing 3 of the pump casing.
It is structured as a continuation of 7. The outlet chamber 25 is closed off by a lid 32. The bearing housing 37 has a radial bore 2γ, which originates from the outlet chamber 25 and opens into the annular groove 26. Annular groove 2
6 is within the inner peripheral surface of the bearing casing 31 and is limited by the outer peripheral surface of the rotor. However, the annular groove 26
is formed on the outer peripheral surface of the rotor, and the bearing casing 3
It may be limited by the inner circumferential surface of 7. The rotor has radial holes 28. This bore is located in a perpendicular plane with the annulus groove 26, so that the bore 28 connects the inner bore 21 of the rotor with the annular groove. Hole 28
is circulating and happens to be in the drawing plane in Figure 1.

The rotor has a slightly enlarged turning at the bearing end which projects into the crank casing 2, into which the drive shaft of the motor projects with a connecting plate 15. The drive shaft 3 can be, for example, the drive shaft of an injection pump reservoir.

The connecting plate 15 is fixed to the drive shaft with screws 18. The connecting plate 15 has a connecting tongue piece 16 at one location on its circumferential surface, and the connecting tongue piece engages in a notch 17 (see FIG. 3) of the rotor 5, and in this case, the axis of the rotor Directional mobility is not hindered. The drive shaft 3 and screw 18 have a central oil supply hole 19 . This axial hole branches into two or more oil injection holes 20 in a fork shape within the screw. They are arranged so that they are facing no direction.

The rotor has an annular collar 22 within the bore 21 which is seated between the radial bore 28 and the end of the rotor. It can be seen that the free end of the rotor is open. That is, an annular gap is formed between the inner peripheral surface of the collar 22 and the head of the screw 18, and between the connecting plate 15 and the turned part 23, and this annular gap is formed between the inner hole 21 of the rotor and the connecting casing. Connect with.

The rotor 5 is driven by the drive shaft 3 in the direction of rotation indicated by the arrow 35. At this time, the blade 7 performs a relative movement within the guide slit 6, and is in close contact with both ends, and 7t? It comes into contact with the circumferential surface of the pump casing 4 in a sliding manner.

The large radius of curvature of the blade ends has the advantage that the surface pressure of the blades on the casing circumferential surface is low and, on the other hand, a relatively wide gap is created between each blade head and the casing circumferential surface. In this gap, an oil cushion can occur which has dynamic support on the one hand and good sealing action on the other hand. Due to the large radius of curvature, the contact line of the blade head on the casing circumferential surface changes constantly.

This results in good cooling on the one hand and no local overheating of the blades due to friction. On the other hand, this also reduces wear and results in a more even distribution of friction, so that a long service life of the blades is expected.

The invention allows the use of vanes with large head radii, and which nevertheless allows the pump casing, seen in cross section, to be equidistant to the curve K designed for the center of the curved circle of the vane head. The linear design ensures a close contact of the blade head against the housing circumference in each rotational position.

In this case, the use of a vane with a sealing strip 8 on the vane head (
This is not necessarily necessary. However, the sealing strip can be used to compensate for manufacturing tolerances and for wear on the pump casing and vanes.

When using the length of the sealing strip, it is important that the sealing strip is widened significantly outside the groove 9, almost to the width of the vane. This makes it possible to produce sealing strips with a large radius of curvature, so that the contact line of the head of the sealing strip 8 changes within a wide range during rotation of the rotor. If the end of the head of the sealing strip is designed to have approximately the same thickness as the blade, this end will have only a small amount of oil flowing into the rotor at bottom dead center, as shown in FIG. has the advantage that it is only contained and entrained in the guide slit 6. On the other hand, the fact that the head end of the sealing strip is slightly narrower than the blades prevents the sealing strip from getting caught on the longitudinal edges of the slit when the blades run with the sealing strip into the slit of the rotor. do.

As can be seen in particular from FIG. 1, the rotor is a tube with an equal outside diameter over its entire length. This rotor (i
It has stability. Because of this improved stability, it is possible to construct the rotor in thin layers and therefore with less mass.

In a rotor of this configuration, the wall thickness is limited by the fact that the rotor wall must provide a good guide for the blades in the guide slit 6, that is, a guide that seals well and induces a small surface pressure. be done.

Furthermore, this configuration of the rotor allows for a relatively small outer diameter of the rotor, in which case the difference between the length of the blades and the outer diameter of the rotor (apart from the blade thickness) determines the output of the Habo pump. It is well known to do so.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the casing, FIG. 2 is a vertical sectional view of the casing, and FIG. 3 is a schematic vertical sectional view of the casing having another configuration. 1... Vane pump, 2... Crank casing,
3... Drive shaft, 4... Pump casing, 5...
Rotor, 6... Guide slit, γ... Vane, 8...
... Seal strip, 9... Groove, 10... Exhaust hole, 1
DESCRIPTION OF SYMBOLS 1... Suction port, 12... Outlet, 13... Flange, 14... Seal member, 15.'... Connection plate, 16.
-・Connecting tongue piece, 17... Notch, 18... Screw, 1
9... Oil supply hole, 20... Oil injection hole, 21... Inner hole, 22... Brim, 23... Annular gap, 24...
Check valve, 25... Outflow chamber, 26... Annular groove, 27
... hole, 28 ... radial hole, 29 ... equidistant line, 30 ... arrow, 31 ... inflow valve, 32 ... lid, 33 ... annular gap, 34 ...・Axial groove, 35・
...arrow, 36...groove, 31...bearing casing. 4.Casing 5...Rotor 7...Blade

Claims (1)

[Claims] 1. A vane pump, the cylindrical rotor of which has for substantially rigid blades only one guide slit located in a plane containing the axis of the rotor for guiding the blades. In the case of a type in which the casing cross section is constituted by a self-closed curve whose secant line that intersects perpendicularly with the rotor axis has a length approximately equal to the length of the blade, the rotor axis From any group of curves whose secants, which intersect perpendicularly to the blade, have a length approximately equal to the length of the blade, the load on the blade acting in the plane of the blade during radial movement of the blade as well as the frictional force acting on the end of the blade A vane pump characterized in that the curve is selected such that . 2. The vane pump according to claim 1, wherein the curve is selected so that the pressing force acting on the vane in a direction perpendicular to the plane of the vane is minimized. 3. The curve closely fits the rotor cross section over a secant section at least equal to the width of the guide slit in the discharge and/or suction region at bottom dead center and forms a sealing region; 3. The vane pump according to claim 1, wherein the radius of curvature of the curve is smaller than 1/2 of the length of the vane. 4. The vane pump according to claim 3, wherein the radius of curvature of the curve in the seal area is approximately equal to or greater than the rotor radius. 5. The blade edge that contacts the casing peripheral wall spans at least 2/3 of the blade thickness, and at least 1/3 of the blade thickness.
curved with a radius equal to 2, and the casing peripheral wall is equidistant from the curve drawn by the center of the rounded blade edge, having a distance of said radius when viewed in cross section of the casing. A vane pump according to claim 1. 6. From the group of arbitrary curves whose secant line that intersects the rotor axis perpendicularly has a length approximately equal to the length of the blade,
Claim 5, wherein a curved line is selected whose radius of curvature in the region of the bottom dead center is 1/2 or less of the length of the blade.
Vane pump as described in section.