EP0004120B1

EP0004120B1 - Gear-type machine with relief means for the liquid in the interengagement space between the teeth

Info

Publication number: EP0004120B1
Application number: EP19790200119
Authority: EP
Inventors: Theodorus Henricus Korse
Original assignee: Theodorus Henricus Korse
Priority date: 1978-03-10
Filing date: 1979-03-09
Publication date: 1983-04-06
Also published as: DE2810563C2; US4290739A; DE2810563A1; EP0004120A2; EP0004120A3

Description

The invention relates to a gear machine (pump or motor) with helical gears meshing in external or internal engagement, the shafts of which are rotatably mounted in the housing and / or housing cover or in bearing bodies arranged in the housing, the engagement area on the side surfaces facing the gearwheels, i.e. in the Housing wall and / or housing cover or in the bearing bodies, recesses are formed, of which the recesses on the pressure chamber side are connected to the pressure chamber and the recesses on the suction chamber side are connected to the suction chamber. The recess on the pressure chamber side and the suction chamber side in a side surface facing the gearwheels are separated from one another by a web of a certain width.
Known gear machines of this type with straight toothing have the disadvantage that the pinch oil space formed in the engagement area of the toothing changes its volume very quickly, as a result of which the pressure fluid can flow in and out of the pinch oil space with difficulty due to the relatively small squeezing areas of the recesses. The pressure fluid in this pinch oil chamber is squeezed and decompressed despite possible theoretically correctly dimensioned recesses, which results in pressure pulsations, cavitation and noise.
This is difficult to avoid with the most commonly used spur gearing because the size of the squeezing surface as a function of the angle of rotation of the driving wheel cannot be greater than in the case of optimally designed recesses, i.e. Recesses that are arranged approximately symmetrically to the pole in the engagement area as possible on both end faces of the toothing.
FR-A-2 352 947 describes a straight-toothed gear machine with at least one recess, in which the distance between the recess parts to the connecting line of the center points is selected such that the changeover point of the sealing tooth engagement and the single engagement point of a gear pair coincide on the pressure side. Because of this asymmetrical reversal, the recess on the suction chamber side is arranged asymmetrically with respect to the recess on the pressure chamber side, with respect to the connecting line of the gearwheel centers.
FR-A-1355756 describes a gear machine with helical gears, in which a pressure space-side or suction space-side recess is arranged in a side surface.
In another known gear machine, a backlash of zero or almost zero is aimed for in order to achieve a greatly reduced flow rate fluctuation and torque fluctuation. Zero or almost zero is understood to mean a backlash that is less than the usual backlash of z. B. 0.3 mm. This is achieved in that in the case of this straight toothing with no or almost no flank play, the web width between the recess on the pressure chamber side and on the suction chamber side is reduced to half the value - compared to that of the same toothing with flank play. The problem of squeezing the hydraulic fluid and cavitation in an enclosed tooth gap occurs even more than in the case of a gear machine with backlash.
The invention has for its object to provide a gear machine of the type mentioned, in which the available squeezing areas are so large that the hydraulic fluid can flow into the squeezing oil chamber without squeezing or risk of cavitation and can also flow out of it again.
This object is achieved according to the invention in that the pressure-space side and saugraumseitige recess on the leading end side of the helical gear from the symmetry position to the pole by a distance% to the line connecting the two center points of the gears is shifted in the direction of the suction chamber transversely and in that the pressure-space side and saugraumseitige _' Recess on the trailing end of the helical toothing is shifted from the symmetry position to the pole by an equally large distance 1/2 transversely to the connecting line of the two center points of the gear wheels in the direction of the pressure chamber. The pressure chamber side and the suction chamber side recess on the leading end face of the helical toothing are thus offset by a distance V in the suction chamber side compared to the pressure chamber side or the suction chamber side recess on the trailing end side of the helical toothing.
The web width is unchanged from that of the comparable spur toothing of the same face cut. The size of the displacement of the recesses is independent of whether there is backlash or not.
The technical progress that can be achieved with the invention is based on several advantages. In particular, compared to the comparable straight toothing, the available squeezing surfaces of the recesses are considerably larger and can also flow into the squeezing oil space and also flow out of it again via the gaps of the tooth flanks, which partially lie outside the mechanical engagement area. Only through this advantage according to the invention is it possible for the displacement process to take place undisturbed, for the theoretical fluctuation in the flow rate to be minimal, and for the hydraulic fluid to flow in or out of the enclosed tooth space undisturbed without the risk of being crushed or cavitated. Since not only the hydraulic noises, but also the mechanical noises are lower in this gearwheel machine according to the invention, the tooth shows wheel machine with a low technical effort to a very low sound pressure level, ie compared to a known gear machine with the same flow rate, the speed can be higher and the stroke volume can be smaller in the gear machine according to the invention at the same sound pressure level.
Since the theoretical flow fluctuation of a helical gear and a comparable straight toothed gear machine is approximately the same, the pressure pulsation caused by this theoretical flow fluctuation is approximately the same for both gear machines.
The invention is illustrated in the drawing using several exemplary embodiments. Show it:

1 shows the section 1-I of the gear machine according to FIG. 2,
1a shows the longitudinal section through a modified embodiment of the invention,
2 shows the section 11-11 of Fig. 1,
3 shows the section III-III from FIG. 2,
4 the recesses for helical teeth with backlash,
5 shows the squeezing surface of a spur toothing comparable to the helical toothing according to FIG. 4 with backlash at a certain angle of rotation ϕ ₁ ,
6 shows the squeezing surface of a helical toothing according to FIG. 4 for the same angle of rotation ϕ ₁ according to FIG. 5,
7 shows a modified embodiment for the recesses (with helical teeth with backlash), conforming to FIG. 4,
8 shows a straight toothing comparable to the helical toothing according to FIG. 9 without backlash,
9 the recesses for a helical toothing without or almost without backlash,
10 shows the section III-III from FIG. 2, but in a gear machine without or almost without backlash,
Fig. 11 shows a modified embodiment for the recesses on the rear leading end face of a helical toothing without backlash and
Fig. 12 shows the embodiment of FIG. 11 with the recesses on the front trailing end.

The gear machine according to FIGS. 1 to 3 has a housing 1 which is closed on both sides by housing covers 2 and 3. The housing 1 has a continuous housing opening 4 which is formed by two intersecting bores 5 and 6. The housing opening 4 has approximately the shape of an eight. In the bore 5, two bearing bodies 7 and 8 are arranged, in the bearing bores 9 and 10, a driving gear 11 is rotatably mounted. Likewise, two bearing bodies 12 and 13 are arranged in the bore 6, in whose bearing bores 14 and 15 the driven gear wheel 16 is rotatably mounted.
1a consists of a housing 1a with only one housing cover 2a. The gears 11 and 16 are rotatably supported with their shafts directly in the housing 1a or in the housing cover 2a.
The driving gear 11 has right-hand teeth; the driven gear 16 has left-rising teeth. The driving gear 11 is driven clockwise. In the bearing bodies 7 and 12 on the leading end face 17 of the helical toothing and in the bearing bodies 8 and 13 on the trailing end face 18 "of the helical toothing, recesses 19, 20, 21, 22 are provided in order to achieve a maximum squeezing area and a minimal flow fluctuation so that with decreasing volume of the enclosed tooth gap, the enclosed tooth gap is connected to the pressure chamber D via the recesses 19 and 21 displaced by a distance V from one another, and that with increasing volume of the enclosed tooth gap the enclosed tooth gap is connected via the recesses displaced by a distance V from one another 20 and 22 is connected to the suction chamber S.
Since the area of the enclosed tooth gap in the center of the wheel becomes smaller as the volume of the enclosed tooth gap decreases and the area of the enclosed tooth gap in the center of the wheel increases with increasing volume of the enclosed tooth gap, it can be determined exactly for which angle of rotation ϕ ↑ of the driving gear 11 the included one Tooth gap reaches its smallest volume and when the so-called pressure changeover process has to take place.
From Fig. 4 is given for a helical toothing with backlash, how the recesses 19 to 22 are designed; The center distance extends from the center M, of the driving helical gear 11 with right-hand teeth to the center M _{2 of} the driven helical gear 16 with left-hand teeth. The pole P lies on the center of the connecting line from M to M _2. The thin solid line 23 follows the contours of the toothing on the front trailing end face 18 of the helical toothing. The thin dash-dotted line 24 follows the contour of the toothing on the rear leading end face 17 of the helical toothing. The thick line 25 represents the contour of the helical toothing in the center of the wheel. The helical toothing is drawn for the position in which the enclosed tooth gap reaches its smallest volume or in which the hatched area of the enclosed tooth gap 26 reaches its minimum in the wheel center.
The pressure changeover process takes place at this very moment, ie the tooth gap is separated from the pressure chamber D and connected to the suction chamber S. The recesses of the helical toothing with backlash are matched to this pressure changeover process. In this case, the straight web edges 27 and 28 of the essentially rectangular recesses 19 and 20 of parallel to M _i , M ₂ are left on the rear leading end face 17 of the helical toothing fenden lines formed by the two in this rear leading end face 17 lying on the engagement plane 29 contact points 30 and 31. Likewise, on the front trailing end face 18 of the helical toothing, the straight web edges 32 and 33 of the substantially rectangular recesses 21 and 22 of lines running parallel to M _i , M ₂ are through the two contact points 34 lying in this front trailing end face 18 on the engagement plane 29 and 35 formed.
The line of symmetry 88 to the web edges 27, 28 is offset in the direction of the suction space S by a distance% and the line of symmetry 89 to the web edges 32, 33 is offset in the direction of the pressure space D by a distance% to the connecting line M _i M ₂
3 shows the recesses 19, 21 and 20, 22 shifted by the distance V. The depth 36 of the recesses 19 to 22 is a few millimeters and the width 37 of the recesses 19 to 22 is approximately equal to the tooth height. The recesses 19, 20 and 21, 22 on the pressure chamber side and suction chamber side, respectively, located on one end face of the toothing, are separated from one another by a web with the width 38. The web width 38 is, compared to the web width 39 of the comparable straight toothing shown in FIG. 5 with the same face cut, still large.
In order to be able to compare the greatly different size of the squeezing surface of the helical toothing with that of the comparable straight toothing, the squeezing surfaces available for the straight toothing for a torsion angle ϕ ₁ are shown in FIG. 5 and the squeezing surfaces available for the helical toothing in FIG. 6. As shown in FIG. 5, the squeezing surface 40 is available on both end faces of the straight toothing. As FIG. 6 shows, the squeezing surface 41 is available on the leading end face 17 and the squeezing surface 42 is available on the trailing end face 18. In addition, a squeezing surface with a gap 43 is available. It clearly follows from this that the helical gear machine with the arrangement of the recesses 19, 20, 21, 22 according to the invention has a larger squeezing area and therefore a better flow than the comparable straight gear machine.
Of course, the recesses 19 to 22 on the two end faces 17, 18 of the helical toothing can also have a somewhat different shape. However, the recesses must always be designed in such a way that the enclosed tooth gap is connected to the pressure chamber D via the recesses 19, 21 on the pressure chamber side only with decreasing size of the area of the enclosed tooth gap in the wheel center and that only with increasing size of the area of the enclosed tooth gap in the wheel center the enclosed tooth gap is connected to the suction space S via the recesses 20, 22 on the suction space side.
7, the essentially rectangular recesses 19, 20, 21, 22 with straight web edges 27, 28, 32, 33 were assumed. In addition, with these recesses at the intersection of the web edges 27, 28, 32, 33 with the engagement plane 29, notches 44, 45, 46, 47 are made, which are defined by the root circle 48, 4.9 and the root circle contour 50, 51, 52, 53 Tooth flank of the adjacent gearwheel is formed at an angle of rotation, ₁ at which the area of the enclosed tooth gap in the wheel center reaches its minimum. These notches 44 to 47 increase the available squeezing area even more.
Even in the case of a gear machine without backlash, helical gearing can be used in an analogous manner by moving the recesses on the pressure chamber and suction chamber side by a distance% in the direction of the suction chamber S and the displacement of the recess on the pressure chamber and suction chamber side by a distance% in according to the invention on the trailing end In the direction of pressure chamber D, the size of the squeezing area can be increased considerably. The web width 77 is equal to the web width 54 of the comparable straight toothing without or almost without backlash, as can be seen from FIGS. 8 and 9.
It also applies here in the same way that, in order to achieve a maximum squeezing area and an undisturbed conveying process, the recesses are designed such that, with the volume of an enclosed tooth gap decreasing, the enclosed tooth gap via the recesses 55 and 56 with the pressure chamber D displaced by a distance V from one another is connected, and that as the volume of the enclosed tooth gap increases, the included tooth gap is connected to the suction chamber S via the recesses 57 and 58 on the suction chamber side displaced by a distance V from one another.
Since the size of the area of the enclosed tooth gap in the center of the wheel becomes smaller as the volume of an enclosed tooth gap decreases and the size of the area of the enclosed tooth gap 59 increases in the center of the wheel as the volume of this included tooth gap 59 increases, it can be done in the same way as for the helical teeth with backlash be determined for which angle of rotation ϕ ↑ of the driving gear 11 this enclosed tooth gap reaches its smallest volume and therefore when the pressure changeover process must take place.
For a helical toothing with the same face cut as the helical toothing according to FIG. 4, but without or almost without backlash, FIG. 9 shows how the recesses 55, 56, 57, 58 according to the invention are designed. The thin solid line 60 follows the contours of the helical teeth on the front trailing end 61 of the helical teeth. The thin dash-dotted line 62 follows the contours of the Helical teeth on the rear leading end face 63 of the helical teeth. The thick line 64 represents the contour of the helical toothing in the center of the wheel.
The helical toothing is drawn in the position in which an enclosed tooth gap reaches its smallest volume or in which the hatched area of the enclosed tooth gap 59 is smallest in the center of the wheel. At this very moment, the pressure reversal process must take place, i. H. the tooth space is separated from the pressure chamber D and connected to the suction chamber S. The recesses 55 to 58 of the helical toothing are matched to this pressure reversing process with no or almost no backlash.
In this case, the straight web edges 65 and 66 of the substantially rectangular recesses 56 and 58 of lines running parallel to M _i M ₂ are on the rear leading end face 63 of the helical toothing through the contact points 69 lying in this rear leading end face 63 on the engagement planes 68 and 67 or 70 formed. Likewise, on the front trailing end face 61 of the helical toothing, the straight web edges 71 and 72 of the essentially rectangular recesses 55 and 57 of lines running parallel to M _i M ₂ through the two contact points lying in this front trailing end face 61 on the engagement planes 63 and 67 73 and 74 formed. The line of symmetry 90 to the web edges 65, 66 is in the direction of the suction space S by the distance
and the line of symmetry 91 to the web edges 71, 72 is in the direction of the pressure space D by the same distance
offset to the connecting line M ₁ M ₂ .
As can be seen from FIG. 10, the depth 75 of the recesses 55 to 58 is a few millimeters. The width 76 of the recesses 55 to 58 is approximately equal to the tooth height. The recesses 56, 58 and 55, 57 on the pressure chamber side and suction chamber side, respectively, located on one end face of the helical toothing, are separated from one another by a web with the width 77. The web width 77 has remained unchanged compared to the web width 54 of the comparable straight toothing shown in FIG. 8 without or almost without backlash with the same face cut.
Of course, the recesses 55 to 58 on the two end faces 61, 63 of the helical toothing can also have a slightly different shape: the recesses must always be designed such that, with the size of the area of an enclosed tooth gap in the center of the wheel being removable, the enclosed tooth gap is above the pressure chamber-side recesses 55, 56 is connected to the pressure chamber D and that with increasing size of an area of the enclosed tooth gap in the center of the wheel, the enclosed tooth gap is connected to the suction chamber S via the recesses 57, 58 on the suction chamber side.
In the exemplary embodiment according to FIGS. 11 and 12, the essentially rectangular recesses 55, 56, 57, 58 with straight web edges 71, 65, 72, 66 have been assumed. In addition, with these recesses at the intersection of the web edges 71, 65, 72, 66 with the engagement planes 67 and 68, notches 78, 79, 80, 81, 82, 83, 84, 85 are made, which are from the root circles 86, 87 and contours of the tooth flank of the adjacent gearwheel on the root circle are formed at an angle of rotation ϕ ₁ at which the area of an enclosed M ₁ or M ₂ side tooth gap in the wheel center reaches its minimum. These notches 78 to 85 increase the available squeezing area even more. 11 and 12, the construction of the notches 79, 81, 82, 84 is shown only for the angle of rotation cp, at which the area of the enclosed tooth space on the M _z side reaches its minimum in the center of the wheel.

Claims

1. A gear pump or gear motor comprising a pair of intermeshing driving and driven helical gears (11, 16), a housing surrounding said gears and providing pressure ports and suction ports leading to said gears, pressure port connected and suction port connected relief grooves (19, 20, 21, 22 or 55, 56, 57, 58), formed in the meshing area in the housing and/or the stationary parts, positioned in the pump, said relief grooves facing the lateral faces of the helical gears; said pressure port connected and suction port connected relief grooves (19, 20 or 56, 58) at the leading lateral face (17 resp. 63) of the helical gears having been shifted, out of the symmetrical position with respect to the plane through the two rotation axes, over a distance ^v/2 in the direction of the suction port, said pressure port connected and suction port connected relief grooves (21, 22 or 55, 57) at the lagging lateral face (18 resp. 61) of the helical gears having been shifted, out of the symmetrical position with respect to the plane through the two rotation axes, over a distance % in the direction of the pressure port, said distance % having been given that value, that an enclosed toothcavity (26, 59) is connected via the pressure port connected relief grooves (19, 21 or 55, 56) with the pressure port, only with decreasing size of the area of the enclosed tooth cavity, considered in the transversal plane through the middle of the gears and that an enclosed tooth cavity is connected via the suction port connected relief grooves (20, 22 or 57, 58) with the suction port, only with increasing size of the area of the enclosed tooth cavity, considered in the transversal plane through the middle of the gears.

2. In a gear pump or gear motor as in claim 1 comprising a pair of helical gears, meshing with tooth clearance; straight land edges (27, 28) of somewhat rectangular relief grooves (19, 20) at the leading lateral face (17) of the helical gears go through the contact points, positioned on the pressureline at said leading lateral face, said land edges running parallel with the line of centers and straight land edges (32, 33) of somewhat rectangular relief grooves (21, 22) at the lagging lateral face of the helical gears go through the contactpoints, positioned on the pressureline at said lagging lateral face, said land edges running parallel with the line of centers, said helical gears being considered for a rotation angle, for which the size of the area of the enclosed tooth cavity, considered in the transversal plane through the middle of the gears, reaches its minimum.

3. A gear pump or gear motor as in claim 1 or 2 wherein in the land somewhat triangular notches (44, 45, 46, 47) have been formed which, starting from the intersection point of a land edge with the pressureline, follow the contours of the toothflank along the foot in the direction of the most adjacent rootcircle and of said rootcircle, said helical gears being considered for a rotation angle, for which the size of the area of the enclosed tooth cavity (26), considered in the transversal plane through the middle of the gears, reaches its minimum.

4. In a gear pump or gear motor as in claim 1 comprising a pair of helical gears, meshing with no or nearly no tooth clearance; straight land edges (65, 66) of somewhat rectangular relief grooves (56, 58) at the leading lateral face (61) of the helical gears go through the contactpoints (69, 70), positioned on the pressurelines at said leading lateral face, said land edges running parallel with the line of centers and straight land edges (71, 72) of somewhat rectangular relief grooves (55, 57) at the lagging lateral face (61) of the helical gears go through the contactpoints (73, 74), positioned on the pressurelines at said lagging lateral face, said land edges running parallel with the line of centers, said helical gears being considered for a rotation angle for which the size of the area of an enclosed tooth cavity at the side of the driving or of the driven gear, considered in the transversal plane through the middle of the gears, reaches its minimum.

5. A gear pump or gear motor as in claim 1 or 4 wherein in the land somewhat triangular notches (78, 79, 80, 81, 82, 83, 84, 85) have been formed which, starting from an intersectionpoint of a land edge with a pressureline, follow the contours of the toothflank along the foot in the direction of the most adjacent rootcircle and of said rootcircle, said helical gears being considered for a rotation angle for which the size of the area of an enclosed tooth cavity at the side of the driving or the driven gear, considered in the transversal plane through the middle of the gears, reaches its minimum.