JPS63109293A - 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 INDUSTRIAL APPLICATION The present invention relates to a base pontoon in which the rotor has only one guide slit for guiding the blades.

This type of vane pump is the second patent application published in West Germany.
521.190.

In the prior art, a guide slot is located in the axial plane of the rotor, in which only one blade is guided in a radial sliding manner. This casing is constructed from Pascal's slant. The vanes themselves have sharp edges at both ends that engage the casing. The design of the housing section as a Pascal spiral and the sharp design of the blade ends make it geometrically possible to construct a vane pump with only one blade.

In particular, the use of vane pumps as vacuum pumps serves to create a vacuum in brake booster reservoirs in diesel engine motor vehicles and other injection engine motor vehicles and for operating other servo consumers in motor vehicles. However, such a pot has the following drawbacks. This means that the blade ends, which in this case are configured as sharp edges, wear out very quickly and, moreover, if the theoretical efficiency of the pump is to be achieved, it is necessary to manufacture the casing and the blades in a completely dimensionally stable manner. be. However, due to wear and temperature effects, known vane pumps lose their tightness very quickly and can no longer be used as vacuum pumps.

In the rotary vane compressor known from West-Italy Patent No. 2,407,293, only one blade is
It has two longitudinal sealing strips, both of which extend in the axial direction, are in close contact with the cylinder casing, and are guided in grooves provided in each case at the ends of the vanes.

Also, Swiss Patent No. 540434 and Swiss Patent No. 63
In the vane pump known from US Pat. No. 4,385,
The blade edges are curved with a large radius. Furthermore, the casing peripheral wall has a rounded chamfer when viewed in a vertical cross-sectional view of the casing.
It is constructed as an equidistant curve to Pascal's spiral drawn by the center point of the edge. In this case, the spacing of the equidistant curves is equal to the radius of curvature of the blade spacing.

With this design, the blade ends always contact the housing jacket with the largest possible sealing surface, and the blades are guided in the housing with almost no play.

OBJECT OF THE INVENTION The object of the invention is to improve the known vane pumps with only one vane and to provide a vane pump which is suitable as a vacuum pump and which has a large displacement volume, high efficiency and a long service life. It is.

Means for Solving the Problem In order to solve this problem, in the configuration of the present invention, the equidistant curve is defined by the formula %.

In order to allow relatively large tolerances, it is furthermore proposed to provide the blade ends with radially movable strips. The radial play of this vane is in any case extremely small due to the proposed configuration of the housing, and the radial play is 0.
It is not necessary to exceed 5-1 mm.

In order to ensure the sealing of the sealing strip against the inner circumferential surface of the casing, it is furthermore necessary that the head of the sealing strip be
It is suggested that if it extends out from the groove it should be approximately the same width as the blade thickness. Advantageously, the guide strip is slightly narrower than the width of the vane, so that the sealing strip is prevented from being squeezed when the vane enters the slot.

Furthermore, the delivery volume can be further increased by having an edge radius of the blade edge not greater than half the blade thickness. In this case, it is true that a reduction in the sealing effect must be accepted, but geometrical dimensions that mean an increase in the delivery volume become possible. The lower limit of the edge radius is determined by the desired sealing effect to be achieved. What should be taken into account in this case is that the vane pump is lubricated with oil and that the formation of a ring-shaped oil film on the casing wall also provides a sealing effect. The minimum value of the radius must therefore in particular ensure that the blades float on the oil film without wear as much as possible during rotation and the centrifugal forces caused thereby. Therefore, the lower limit of the edge radius is approximately 1/4 of the blade thickness), and in practice, it is approximately 1/4 of the blade thickness.
/3 is desirable.

Example The invention will now be described in detail with reference to the drawings.

The vane pump 1 shown in FIGS. 1 and 3 is flanged to a crank casing 2 of an automobile by a flange 13 and sealed by a sealing member 14. A cylindrical rotor 5 is rotatably supported on the pump casing 4 . For this purpose, the pump housing with the cross-sectional shape described below has an eccentric addition forming a bearing housing 37. The bearing housing 37 projects into the crank housing and is centered there. The rotor 5 is supported so as to be in circumferential contact with the support casing 37 at the bottom dead center. The bearing casing 37 forms, so to speak, a sliding bearing for the free end of the rotor 5.

The drawing therefore shows an axial groove for lubricating this plain bearing.

The rotor 5 is a tube with equal outer diameter between its ends. Bore 21 extends over the entire length of the tube. In the area of the casing the tube has only one guide slit 6
, which guide slit lies in the axial plane, passes through the bore and has an axial length that corresponds exactly to the axial length of the pump casing 4 . Only one blade 7 is slidably guided in the guide slot 6.

The width of the vane 7 corresponds to the axial length of the pump casing. The vane 7 can also consist of one piece, but in the embodiment shown it has a sealing strip 8 at its end, which sealing strip can slide radially in a groove 9 in the vane 7. Although it is possible, you are advised to do so in secret. The air bleed hole 10, which connects the bottom of the groove 9 in the direction of rotation with the front side of the vane, ensures that the highest pressure in the pump always exists in the groove 9, which forces the sealing strip 8 outwards. guarantee that it will be done. In any case, even if the vane 9 consists of one piece, as shown in FIG. Based on the cross-sectional shape of the casing, which will be described later, it comes into close contact with the inner circumferential surface of the casing 4 at any rotational position. Furthermore, the blade end has an edge radius r in any case.
It has a round chamfer. This edge radius is chosen to be as large as possible and in any case not larger than 1/2 of the thickness S of the blade 7.

If the vane is provided with a sealing strip, the sealing strip has a bulge outside the groove 9, which spatula r is significantly wider than the groove 9 but extends further along the blade 7 while squeezing. is somewhat narrow.

The circumferential wall of the pump casing 4 is defined in such a way that, in cross-section, the circumferential wall exhibits an equidistant curve with respect to a Pascal spiral with an edge radius (radius of curvature of the blade end) KR.

When designing the cross section of the Tsuashi vane pump, first the blade length, edge radius KR, and outer diameter RR of the rotor 5 are determined. The difference between the blade length and the outer diameter RR of the rotor approximately determines the pump output. This difference is limited by strength and other considerations. The blade length is defined by the length of the casing dividing line passing through the center point M of the rotor. After defining the entire circumference of the casing as a Pascal spiral or as an equidistant curve to the Pascal spiral, this secant line has the same length in all rotational positions of the rotor. As a result, the casing radius GR
is 1/2 of the secant length, which gives the theoretical casing center point GM. The distance between the casing center point GM and the rotor center point M is designated as the eccentricity E. Since the rotor is supported in the pump casing in such a way that the rotor is in circumferential contact with the pump casing at the bottom dead center, the vanes 7 are inserted into the guide slits of the rotor 5 at the bottom dead center as shown in FIG. It completely sinks into 6. A Pascal spiral is now formed centered on the center point M of the pump rotor 5 instead of the center point of curvature of the blade end. As a result, the circumferential wall of the pump housing 4 is produced as an equidistant curve with a distance KR. It moves along Pascal's spiral centered on the center point of the rotor, which is caught in the center of curvature of the blade end. This ensures that the vanes are always in close contact with the circumferential surface of the pump casing 4 at their vane ends.

If, as mentioned above, the edge radius KR is chosen as small as possible, in any case less than half the thickness of the vane, a pump casing with an optimally large delivery volume is constructed. obtain.

The discharge volume is primarily defined by the difference between the cross-sectional area of the casing and the cross-sectional area of the rotor. The cross-sectional area of the rotor is kept small by selecting the rotor radius RR to be smaller than the eccentricity E plus the edge radius KR.

The edge radius KR should be chosen to be as small as possible.

Furthermore, this relationship dictates that the ratio (GR-KR)/E must have certain limits.

In this case, it was confirmed that the optimal value is at 2. For a given ratio greater than 2.25, the advantages in terms of discharge volume are greatly outweighed by other disadvantages, especially in terms of strength. Also, this ratio is 1.7
Below 5, an unstable blade movement occurs, so that in this case it is necessary to design the blades very strongly and they are exposed to significant wear.

As shown in FIG. 2, the pump casing 4 has an inlet 11 with a check valve 31 inside and an outlet 12 with a check valve 24 inside as well. The inlet 11 is offset by approximately 90° with respect to the dead center position, and the outlet 12 is located in the region before the bottom dead center in the direction of rotation (arrow 35).

As shown in FIG. 1, the inlet valve 31 is constructed as a mushroom-shaped valve.

This check valve is a mushroom-shaped rubber body that is inserted into a perforated valve plate with its handle and makes intimate contact with the valve plate at the edge of the head, closing the hole in the valve plate in this case. are doing. When air enters, the head is turned over in the suction direction to open the suction opening. In the opposite direction, the hetu blocks the intake opening.

As shown in FIGS. 1 and 3, the outlet initially has a groove 36 in the end face of the pump casing, which groove extends over a large outlet area. This groove 36
Starting from the outlet passage 12 passes through the casing lid,
It is open at the outlet chamber 25. The check valve 24 is designed as a spring-plate valve and is clamped at one end and covers the outlet opening in the outlet chamber 25 . The outlet chamber 25 is configured to surround the valve pressure valve 24 and connect to a bearing casing 37 of the pump casing.

The outlet chamber 25 is closed by a lid 32. The bearing housing 37 has a short radial bore 27 which opens into the annular groove 26 starting from the outlet chamber 25 . The annular groove 26 is located on the inner circumference of the bearing casing 37 and is limited by the outer circumference of the rotor. The annular groove 26 is formed on the outer circumferential surface of the rotor and may be limited by the inner circumferential surface of the bearing casing 37 . The rotor has a radial bore 38 which lies in the same vertical plane as the annular groove and thus connects the inner bore 21 of the rotor with the annular groove. The radial hole 28 rotates and the first
In the figure, it is simply located in the drawing plane by chance.

The rotor has a somewhat enlarged turning 23 at its bearing end projecting into the crankcasing 2, into which the clutch plate 15 of the engine drive shaft projects.

The drive shaft 3 is, for example, a drive shaft for an injection pump. Clutch plate 15 is fixed to the drive shaft with screws 18. The clutch plate has a clutch tongue 16 at one point around its entire circumference, which clutch tongue engages in a recess 17 in the rotor 5 without preventing the axial movement of the rotor 5. The drive shaft 3 and the screw 18 have an oil supply hole 19 in the center. At the screw 18 this oil supply hole branches into two or more oil injection holes 20, which are oriented in the inner bore 21 of the rotor 5 so as not to hit the blades 7. It is being

The rotor 5 has an annular collar 22 in its inner bore 21, which collar 22 is located between the radial bore 28 and the rotor end. It should be noted in this case that the rotor 5 is open at its free end. That is, the inner circumferential surface of the collar 22 forms an annular gap with the heel P of the screw 18 and the clutch plate 15 with the turned part 23, and this annular gap connects the inner hole 21 of the rotor with the clutch casing.

The rotor 5 is driven by the drive shaft 3 in the rotational direction indicated by the arrow 35. At this time, the vane 7 performs a relative movement in the guide slit 6, and is in close and slidable contact with the inner circumferential surface of the pump casing 4 at both ends thereof.

Due to the large radius of curvature of the blade ends, the surface pressure of the blades on the inner circumferential surface of the casing is small, but relatively wide gaps are created between each blade head and the inner circumferential surface of the casing. This gap is preferably of such width that an oil cushion can be formed in the same gap, which has a dynamic supporting force on the one hand and a good sealing effect on the other hand. Due to the radius of curvature, the contact line of the vane head on the inner circumferential surface of the casing always alternates.

On the one hand, this achieves good cooling and avoids localized overheating due to friction. On the other hand, this also reduces wear and makes it possible to increase the service life of the blades due to the uniform distribution of wear. Taking all this into consideration determines the lower limit of the edge radius.

In this case it is not absolutely necessary to use a vane with a sealing strip 8 on the vane hem 1. However, the sealing strip can serve to compensate for errors and for wear on the pump casing and vanes. If a sealing strip is used, it is particularly important that the sealing strip is sufficiently wide outside the groove 9, but not so wide that it spans the entire vane width.

This also makes it possible to produce sealing strips with a radius of curvature KR that is advantageously smaller than l/2 of the blade thickness, and furthermore that the barbed end of the sealing strip is smaller than the blade thickness. The rather narrow width also prevents the sealing strip from getting caught on the longitudinal edge of the guide slit when the vanes enter the guide slit together with the sealing strip.

As can be seen in particular from FIG. 1, the rotor is a tube having an equal outer diameter over its entire length.

The rotor is dimensionally stable in contrast to conventional configurations in which the rotor shaft has a smaller diameter than the rotor. Because of this improved dimensional stability, it is possible to construct the rotor with thinner walls and thus with less material. The wall thickness is limited in this configuration of the rotor by the fact that the rotor wall must form a guide for the vane reservoir which produces a good seal in the guide slit 6, a high sealing property and a low surface pressure.

It should be noted that this configuration of the rotor also allows a relatively small external diameter of the rotor, in which case the difference between the blade length and the external diameter of the rotor approximately defines the pump displacement, ignoring the blade thickness. It won't happen. This configuration of the rotor therefore also serves as a base for the other configurations of the subject of the invention.

However, it is quite decisive that a rotor of this type can be sealed particularly well in the casing. The sealing of the annular gap 33 between the rotor end face and the casing wall in contact therewith takes place in that the negative pressure in the pump casing continues in the annular gap 33 . A central pressure gradient region is formed in this annular gap 33. On the water supply side, the rotor end face is exposed to atmospheric pressure. In this case, a self-regulating effect occurs. That is, when the annular gap 33 is large, the negative pressure in the pump casing 4 disappears over a relatively large radial length of the annular gap, so that the annular surface to which the negative pressure is applied is large, and as a result, the rotors are oriented in opposite directions. The difference in pressure acting on both end faces is also large. There is therefore an automatic adjustment of the crimp force to a value that represents the optimum compromise between sealing and wear.

As can be seen from FIG. 1, a good seal of the rotor on one side does not result in unsealing on the other side. This is because the conditions in the slide bearing (bearing housing 37) do not change during the axial movement of the rotor. Also, sliding bearings have no problems with sealing. This is because the plain bearing can be constructed to any desired length, so that changes in the bearing gap due to temperature changes, for example, do not have any adverse effects.

Other characteristics of the pump include: In this case, the air outlet opens initially over its entire cross section into the interior of the rotor and, through this interior, into the crankcase of the engine. This procedure works for the formation of oil circuits. Lubricating oil is supplied to the pump via an oil supply hole 19 and an oil injection hole 20.

In this case, the oil first reaches the inner bore of the rotor 5 in the area of the slit 6. Centrifugal force distributes the oil as a film on the inner circumferential surface of the rotor. This oil film also surrounds the gap formed by the guide slit 6 and the vane 7.

A further consideration is that the entire pump casing 4 outside the rotor 5 is under negative pressure, not only on the pallet suction side, but also at the outlet 12 after at least a short run.
This means that the outlet side within the range is also under negative pressure.

This is caused by the fact that the pump housing can only be flowed through in the suction direction by means of the check valves 31, 24. Due to the negative pressure and centrifugal force in the pump casing 4, the oil on the inner peripheral surface of the rotor 5 flows through the seal gap of the guide slit 6 and the seal gap (annular gap 33) formed by the end surface of the rotor 5 and the end surface of the pump casing 4. He is pulled into the room and sent to a separate room. In the compartment, the lubricating oil is entrained by the rotating blades and forms a lubricating and sealing film in the lubricating gap between the blade spatula 1 and the inner peripheral surface of the casing. At the same time, however, the lubricating oil is conveyed back through the groove 36 and the outlet 12 to the outlet chamber 25 together with the outflow air. From there, the lubricating oil reaches the annular groove 26 through a short hole 27. This annular groove 2
6 is exposed to atmospheric pressure, so that the lubricating oil can be distributed from there into the bearing gap and into the lubricating grooves of the bearing. A portion of the lubricating oil passes through the bearing gap to the pump casing 4.
The other part leaks into the crank casing. However, most of the lubricating oil contained in the exhaust gas is transported back to the rotor bore 21. From there, excess lubricating oil is transferred to the drive shaft 3 or clutch plate 1.
5 and the screw 18 towards the rotor through which it can return into the crank casing. However, especially if the oil supply via the oil supply hole 19 is small, this return of oil can also be prevented by providing a bulge or collar 22. The radial height of the collar 22 defines how much of the prepared oil is desired to be circulated in the vane pump. Due to the centrifugal force, an oil film having a layer thickness of the flange 22 is formed on the inner circumferential surface of the inner hole 21 together with the oil supplied through the oil supply hole 19 . The external oil supply can therefore be limited to a small amount that is lost in the slide bearing (bearing housing 37) and is drained directly back into the crank housing.

The circulating oil quantity in this case determines not only the lubrication effect but also the sealing effect in the area of the gap.

Alternatively, the outlet 12 can also be arranged on the other end face of the pump housing. In this case, a valve chamber with a check valve is likewise provided on the outside of this other end face. This valve chamber communicates with the chamber formed by the bore 21 via a radially inwardly extending passage and a short axis-parallel passage.

Furthermore, it is also possible to provide a plurality of outlet channels in the pump region of the rotor, each radial outlet channel with a check valve being assigned to a respective compartment. In such an arrangement, it is also ensured that the exhaust gas and the lubricating oil contained therein are returned to the interior of the engine and that the lubricating oil is again available for lubrication. In any case, the collar 22 is located somewhere between the outlet opening into the inner bore 21 of the rotor and the free rotor end. In this case, it is advantageous for the collar 22 to be located between the free rotor end and the beginning of the guide slot 6, so that the lubricating oil returned and stored is in particular in the gap between the guide slot 6 and the vane. Prepared for lubricating and sealing.

[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 view of the casing lid viewed in the axial direction. 1... Vane pump, 2... Crank casing,
3... Drive shaft, 4... Pump casing, 5...
Rotor, 6... Guide slit, 7... Blade, 8.
...Seal strip, 9...Groove, 10...Air vent hole,
DESCRIPTION OF SYMBOLS 11... Inlet, 12... Outlet, 13... Flange, 14... Seal member, 15... Clutch plate, 16
...Clutch tongue piece, 17...Notch, 18...Screw, 19...Oil supply hole, 20...Oil injection hole, 21...Rotor inner hole, 22...Brim , 23...
- Turning part, 24... Check valve (outlet valve), 25... Outlet chamber, 26... Annular groove, 27... Short hole, 28...
・Radial hole, 29... Equidistant curve, 31... Check valve (large mouth valve), 32... Lid, 33... Annular gap, 3
4... Axial groove, 35... Arrow, Fig. 1

Claims (1)

[Claims] 1. A vane pump, wherein the cylindrical rotor of the vane pump has only one guide slit located in the axial plane of the rotor, and is in contact with the casing peripheral wall along the generatrix, In this case, the blade edge in contact with the casing circumferential wall is curved with an edge radius KR over at least 2/3 of the blade thickness, and the casing circumferential wall is, viewed in a vertical section of the casing,
in the form of an equidistant curve drawn by the center point of the curved blade edge and with a spacing of the edge radius KR and a radius GR relative to a Pascal parabola with eccentricity E, A vane pump characterized in that the equidistant curve is defined by the formula 2-0.25<(GR-KR)/E<2+0.25. 2. Only one blade is slidably guided in a guide slot provided in the rotor, the blade having a guide strip at each of its ends, which guide strip has a radius in the groove of the blade. 2. A vane pump according to claim 1, wherein the vane pump is movably and sealed guided with directional play. 3. The vane pump according to claim 2, wherein the portion of the guide strip protruding from the groove is wider than the guide strip body and somewhat narrower than the blade thickness. 4. The vane pump according to any one of claims 1 to 3, wherein the edge radius KR of the blade is 1/2 or less of the thickness of the blade. 5. A patent claim in which the rotor is supported on one side in a cantilevered manner and consists of one member together with a bearing extension provided on one side, and the rotor and the bearing extension have the same outer diameter. The vane pump according to any one of the ranges 1 to 4. 6. The rotor is movably supported in the axial direction, and the drive shaft (3
6. The vane pump according to claim 5, wherein the vane pump is axially movably connected to the vane pump (1) and is under atmospheric pressure on the drive side. 7. The vane pump according to claim 5 or 6, wherein the rotor is supported by a sliding bearing.