EP1658437B1 - Gear tooth and external gear pump - Google Patents

Gear tooth and external gear pump Download PDF

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Publication number
EP1658437B1
EP1658437B1 EP04785984A EP04785984A EP1658437B1 EP 1658437 B1 EP1658437 B1 EP 1658437B1 EP 04785984 A EP04785984 A EP 04785984A EP 04785984 A EP04785984 A EP 04785984A EP 1658437 B1 EP1658437 B1 EP 1658437B1
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EP
European Patent Office
Prior art keywords
tooth
sector
gear
gear pump
convex
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Expired - Lifetime
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EP04785984A
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German (de)
French (fr)
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EP1658437A1 (en
Inventor
João MERENDEIRO
José RIBAFEITA
Quê VU DO
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Renault SAS
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Renault SAS
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/082—Details specially related to intermeshing engagement type machines or pumps
    • F04C2/084—Toothed wheels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/12—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
    • F04C2/14—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
    • F04C2/18—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with similar tooth forms

Definitions

  • the present invention relates to a gear tooth and a pump, in particular an oil pump provided with corresponding gears.
  • this invention relates to a gear tooth having a concave foot at its starting point at the foot of the adjacent tooth, and a head connected to said foot.
  • This tooth finds a preferred, but not exclusive, application in an external gear pump having at least one pair of toothed gears in mutual engagement.
  • Such a pump which is also the subject of the invention, can be used in a combustion engine, but the invention is also applicable to all external gear pumps.
  • Conventional tracks used to increase the hydraulic performance of gear pumps are such as increasing the speed of the pump, increasing the height of the pump gears, reducing the hydraulic clearances, or increasing the number of gears.
  • the oil pumps have low volumetric efficiencies at low speeds, so that they are generally oversized at high speeds, and it is often necessary to discharge a large part of the oil pumped at high speed, or even the half of it, by a discharge valve.
  • a typical gear pump tooth profile as illustrated by the publication GB439 908 , has a concave base followed by a rounded involute head.
  • the object of the present invention is to increase the volume of oil displaced between the teeth by optimizing the profile thereof without prejudice to the continuity of the meshing. Specifically, the objective is to increase the flow, pressure and volumetric efficiency at low speeds of a gear pump, without increasing its size.
  • the invention proposes that the head of each tooth has two convex sectors connected by a transition point marking a break in the curve.
  • the second active point of the profile thus delimits the bottom of a notch inscribed in the profile of the tooth.
  • the first convex sector of the tooth head has a involute profile.
  • the pump proposed by the invention comprises two identical or different toothed wheels.
  • the figure 1 highlights the two main parts of the tooth 1, namely its foot 2 and its head 3, connected by an active transition point 4.
  • the foot 2 has a concave shape, and is connected to its starting point 6, at foot of the neighboring tooth (not shown on the figure 1 ).
  • the tooth head has two convex sectors 7, 8, connected by an active transition point 9, marking a break in the curve.
  • the transition point 9 defines the bottom of a notch inscribed in the profile of the tooth.
  • the convex sector 7 following the first transition point 4 has a involute profile.
  • This involute profile thus extends between the two active transition points 4 and 9 of tooth 1, and constitutes a first convex sector of foot 2.
  • the second convex sector 8, or convex extension profile, which follows point 9 may also have a involute profile, without this particular provision being imperative, and it is possible to envisage other extension profiles for this second convex sector, without departing from the scope of the invention.
  • the head of the tooth has a rounded end sector 11, connected to the second convex sector 8 by a transition sector 12.
  • the tooth is symmetrical, and there is a shape concordance between the end sector 11 of the teeth and the concave sector defined by the juxtaposition of two feet 2 of neighboring teeth, so that the end sector of a tooth, can roll between two teeth of the opposite wheel, keeping in touch with them until it escapes.
  • the tooth 1a of a first wheel has just exceeded the axis of symmetry of the opposite entrance. It is in main support (double circle) by its convex surface 8 with the active transition point 4 of the opposite tooth 1b, while its end sector 11, rolls on the concave foot 2 thereof.
  • the main point of support is between the convex profile 8 of the wheel 1a and the foot 2 of the wheel 1a, while there are two secondary contact points between the two wheels 1b and 1c, respectively between the sector d end 11 of the tooth 1c and the foot of a new tooth 1d, and between the two convex sectors 7 of the teeth 1a and 1c.
  • the main point of support is between the convex sector 7 of the tooth 1c and the active transition point 4 of the tooth 1d, while the head of the wheel 1c, rolls in the transition zone of the teeth 1a and 1d.
  • the end sector continues to roll on the foot 2 of the tooth 1a, while the main support is between the active transition point 4 of the tooth 1d and the convex sector 7 of the tooth 1c ( figure 2E ).
  • the figure 3A shows the very large increase in the amount of displaced entrence compared to a conventional tooth in involute circle, thanks to the lengthening of the height of the tooth and the increase of the interval between the teeth.
  • the figure 3B is a figure of principle, where one can see the different trajectories of several points of the tooth profile proposed by the invention, in the entrance of the conjugated pinion, with a pronounced elongated epicyclic effect, allowing the strong development of the displaced volume. .
  • the tooth profile proposed by the invention has the particularity of combining sections in involute circle whose advantages are already known, with special profile bearing sections. This combination simultaneously ensures a continuity of meshing and a sufficient dentition and a very strong development of the displaced volume of oil.
  • the tooth profile proposed by the invention allows in particular a flow rate gain, especially at a low speed, of the order of 30% to 40%, with respect to a conventional involute pump gearing.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Rotary Pumps (AREA)
  • Gears, Cams (AREA)
  • Dental Tools And Instruments Or Auxiliary Dental Instruments (AREA)

Abstract

The gear tooth (1) has a concave foot (2) connecting it to the neighbouring tooth, and a tip (3) that is connected to the foot by a first transition point (4). The tooth tip has two convex sectors (7, 8) connected by a second transition point (9) in the form of a notch marking a break in the surface of the tooth profile. The convex sectors are both in the shape of arcs that are involute to a circle, and the tooth tip has a rounded surface (11) that is connected to each second convex sector by a transition sector (12). A gear pump has at least one pair of gears with meshing teeth shaped as described above.

Description

La présente invention concerne une dent d'engrenage et une pompe, notamment une pompe à huile munie d'engrenages correspondants.The present invention relates to a gear tooth and a pump, in particular an oil pump provided with corresponding gears.

Plus précisément, cette invention a pour objet une dent d'engrenage présentant un pied concave à son point de départ au pied de la dent voisine, et une tête raccordée audit pied.More specifically, this invention relates to a gear tooth having a concave foot at its starting point at the foot of the adjacent tooth, and a head connected to said foot.

Cette dent trouve une application privilégiée, mais non exclusive dans une pompe à engrenages extérieurs comportant au moins une paire de pignons dentés en engrènement mutuel.This tooth finds a preferred, but not exclusive, application in an external gear pump having at least one pair of toothed gears in mutual engagement.

Une telle pompe, qui fait également l'objet de l'invention, est utilisable dans un moteur à combustion, mais l'invention s'applique également sur toutes les pompes à engrenages extérieurs.Such a pump, which is also the subject of the invention, can be used in a combustion engine, but the invention is also applicable to all external gear pumps.

Les pompes à huile utilisées dans les moteurs sont de deux types : les pompes à engrenages extérieurs avec des dentures droites ou à développante de cercle, et les pompes à engrenages intérieurs, avec des profils de dents trochoïdaux droits ou à développante de cercle.There are two types of oil pumps used in motors: external gear pumps with straight or involute gear teeth, and internal gear pumps with straight or involute trochoid tooth profiles.

Les évolutions actuelles des moteurs, et notamment celles de leurs accessoires, augmentent les besoins en débit et en pression d'huile des pompes utilisées. Par ailleurs, les contraintes d'encombrement dans l'environnement moteur sont de plus en plus fortes.The current evolutions of the engines, and in particular those of their accessories, increase the needs in flow and oil pressure of the pumps used. Moreover, congestion constraints in the engine environment are becoming stronger.

Les voies conventionnelles empruntées pour augmenter les performances hydrauliques des pompes à engrenages sont notamment l'augmentation de la vitesse de la pompe, l'augmentation de la hauteur des engrenages pompe, la réduction des jeux hydrauliques, ou l'augmentation du nombre de pignons.Conventional tracks used to increase the hydraulic performance of gear pumps are such as increasing the speed of the pump, increasing the height of the pump gears, reducing the hydraulic clearances, or increasing the number of gears.

Toutefois, les pompes à huile ont de faibles rendements volumétriques à bas régime, de sorte qu'elles sont généralement surdimensionnées à haut régime, et qu'il est souvent nécessaire de décharger une part importante de l'huile pompée à haut régime, voire la moitié de celle-ci, par un clapet de décharge.However, the oil pumps have low volumetric efficiencies at low speeds, so that they are generally oversized at high speeds, and it is often necessary to discharge a large part of the oil pumped at high speed, or even the half of it, by a discharge valve.

Il existe différents profils de denture de pompe à engrenages extérieurs. La géométrie standard, du type à denture droite à développante de cercle, a des performances modestes. En effet, si on cherche à augmenter le volume d'huile déplacé, en optimisant le profil des dents, on se heurte rapidement à différentes contraintes. La possibilité d'accroître le diamètre extérieur de la dent est limité par la faible épaisseur de celle-ci et par le risque d'avoir une dent trop pointue. Par ailleurs, l'allongement de la dent s'effectue au détriment de la continuité de l'engrènement, notamment au niveau du pied de dent. Enfin, l'interférence entre le cercle de base et le pied de dent, souffre également de l'allongement de celle-ci.There are different external gear pump tooth profiles. The standard geometry, of the right-hand type with involute of circle, has modest performances. Indeed, if we try to increase the volume of displaced oil, optimizing the profile of the teeth, we quickly run into different constraints. The possibility of increasing the outer diameter of the tooth is limited by the small thickness of the tooth and the risk of having a tooth too sharp. Moreover, the elongation of the tooth takes place to the detriment of the continuity of the meshing, in particular at the level of the tooth root. Finally, the interference between the base circle and the tooth base, also suffers from the elongation thereof.

Un profil classique de dent de pompe à engrenages, tel qu'illustré par la publication GB439 908 , présente une base concave suivie d'une tête arrondie en développante de cercle.A typical gear pump tooth profile, as illustrated by the publication GB439 908 , has a concave base followed by a rounded involute head.

Il a déjà été proposé d'améliorer les performances d'une pompe à engrenages extérieurs, en abandonnant les profils à développantes de cercle au profit d'autres profils tels que des épicycloïdes ou des hypocycloïdes se raccordant sur le cercle primitif de la roue dentée, c'est à dire sur la ligne circulaire théorique qui roule sur une ligne équivalente de la roue opposéeIt has already been proposed to improve the performance of an external gear pump, by abandoning the involute circle profiles in favor of other profiles such as epicycloids or hypocycloids connecting to the pitch circle of the toothed wheel, that is to say on the theoretical circular line which rolls on an equivalent line of the opposite wheel

Cependant, les gains ainsi obtenus par rapport aux dentures classiques sont insuffisants. De plus, en s'écartant de celles-ci, on se heurte rapidement à des choix techniques difficiles, et à une augmentation des coûts de fabrication.However, the gains thus obtained compared to conventional teeth are insufficient. Moreover, by departing from these, one quickly comes up against difficult technical choices, and an increase in manufacturing costs.

Le but de la présente invention est d'augmenter le volume d'huile déplacé entre les dents par une optimisation du profil de celles-ci sans préjudice de la continuité de l'engrènement. Plus précisément, l'objectif recherché est d'élever le débit, la pression et le rendement volumétrique à bas régime d'une pompe à engrenages, sans augmenter son encombrement.The object of the present invention is to increase the volume of oil displaced between the teeth by optimizing the profile thereof without prejudice to the continuity of the meshing. Specifically, the objective is to increase the flow, pressure and volumetric efficiency at low speeds of a gear pump, without increasing its size.

Dans ce but, l'invention propose que la tête de chaque dent présente deux secteurs convexes raccordés par un point de transition marquant une rupture de courbe.For this purpose, the invention proposes that the head of each tooth has two convex sectors connected by a transition point marking a break in the curve.

Le second point actif du profil délimite ainsi le fond d'une entaille inscrite dans le profil de la dent.The second active point of the profile thus delimits the bottom of a notch inscribed in the profile of the tooth.

Selon un mode de réalisation préféré de l'invention, le premier secteur convexe de la tête de dent, a un profil en développante de cercle.According to a preferred embodiment of the invention, the first convex sector of the tooth head has a involute profile.

Enfin, la pompe proposée par l'invention, comporte deux roues dentées identiques ou non.Finally, the pump proposed by the invention comprises two identical or different toothed wheels.

D'autres caractéristiques et avantages de l'invention apparaîtront clairement à la lecture de la description suivante d'un mode de réalisation particulier de celle-ci, en liaison avec les dessins annexés, sur lesquels :

  • la figure 1 représente en coupe une dent de roue dentée conforme à l'invention,
  • les figures 2A à 2F illustrent l'engrènement des deux roues de la pompe, et
  • les figures 3A et 3B mettent en évidence les gains obtenus par l'invention.
Other characteristics and advantages of the invention will become clear from reading the following description of a particular embodiment thereof, in conjunction with the appended drawings, in which:
  • the figure 1 represents in section a tooth of toothed wheel according to the invention,
  • the Figures 2A to 2F illustrate the meshing of the two wheels of the pump, and
  • the Figures 3A and 3B highlight the gains obtained by the invention.

La figure 1 met en évidence les deux parties principales de la dent 1, à savoir son pied 2 et sa tête 3, raccordés par un point actif de transition 4. Le pied 2 a une forme concave, et est raccordé à son point de départ 6, au pied de la dent voisine (non représentée sur le figure 1).The figure 1 highlights the two main parts of the tooth 1, namely its foot 2 and its head 3, connected by an active transition point 4. The foot 2 has a concave shape, and is connected to its starting point 6, at foot of the neighboring tooth (not shown on the figure 1 ).

Conformément à l'invention, la tête de dent présente deux secteurs convexes 7, 8, raccordés par un point actif de transition 9, marquant une rupture de courbe. Le point de transition 9, délimite le fond d'une entaille inscrite dans le profil de la dent.According to the invention, the tooth head has two convex sectors 7, 8, connected by an active transition point 9, marking a break in the curve. The transition point 9 defines the bottom of a notch inscribed in the profile of the tooth.

Selon une autre caractéristique de l'invention, le secteur convexe 7 faisant suite au premier point de transition 4, a un profil en développante de cercle. Ce profil en développante de cercle s'étend donc entre les deux points actifs de transition 4 et 9 de la dent 1, et constitue un premier secteur convexe du pied 2.According to another characteristic of the invention, the convex sector 7 following the first transition point 4 has a involute profile. This involute profile thus extends between the two active transition points 4 and 9 of tooth 1, and constitutes a first convex sector of foot 2.

Le second secteur convexe 8, ou profil convexe d'extension, qui fait suite au point 9, peut également avoir un profil en développante de cercle, sans toutefois que cette disposition particulière soit impérative, et on peut envisager d'autres profils d'extension pour ce second secteur convexe, sans sortir du cadre de l'invention.The second convex sector 8, or convex extension profile, which follows point 9, may also have a involute profile, without this particular provision being imperative, and it is possible to envisage other extension profiles for this second convex sector, without departing from the scope of the invention.

Enfin, la tête de la dent présente un secteur d'extrémité arrondi 11, raccordé au second secteur convexe 8 par un secteur de transition 12.Finally, the head of the tooth has a rounded end sector 11, connected to the second convex sector 8 by a transition sector 12.

La dent est symétrique, et il y a concordance de forme entre le secteur d'extrémité 11 des dents et le secteur concave défini par la juxtaposition de deux pieds 2 de dents voisines, de sorte que le secteur d'extrémité d'une dent, peut rouler entre deux dents de la roue opposée, en gardant le contact avec celles-ci jusqu'à ce qu'il s'en échappe.The tooth is symmetrical, and there is a shape concordance between the end sector 11 of the teeth and the concave sector defined by the juxtaposition of two feet 2 of neighboring teeth, so that the end sector of a tooth, can roll between two teeth of the opposite wheel, keeping in touch with them until it escapes.

Enfin, les deux roues dentées de la pompe peuvent être identiques, et cette caractéristique procure un avantage considérable à la pompe proposée, en termes de procédé et de coûts de fabrication.Finally, the two gears of the pump can be identical, and this characteristic provides a considerable advantage to the pump proposed, in terms of process and manufacturing costs.

En se reportant aux figures 2A à 2F (la figure 2F correspondant à la même situation d'engrènement que la figure 2A pour les dents suivantes), on voit qu'il y a plusieurs points de contact entre les dents. Sur ces figures, on a représenté avec un double cercle les points d'appui dits principaux par lesquels la roue menante entraîne la roue menée, et avec un simple des points de contact secondaires permettant d'assurer le rattrapage des jeux de fonctionnement et la continuité de l'engrènement.Referring to Figures 2A to 2F (the figure 2F corresponding to the same meshing situation as the Figure 2A for the next teeth), we see that there are several points of contact between the teeth. In these figures, there is shown with a double circle the so-called main bearing points by which the driving wheel drives the driven wheel, and with a simple secondary contact points to ensure the catching of the operating games and continuity of the meshing.

Sur la figure 2A, la dent 1a d'une première roue vient de dépasser l'axe de symétrie de l'entredent opposé. Elle est en appui principal (double cercle) par sa surface convexe 8 avec le point actif de transition 4 de la dent opposée 1b, tandis que son secteur d'extrémité 11, roule sur le pied concave 2 de celle-ci.On the Figure 2A , the tooth 1a of a first wheel has just exceeded the axis of symmetry of the opposite entrance. It is in main support (double circle) by its convex surface 8 with the active transition point 4 of the opposite tooth 1b, while its end sector 11, rolls on the concave foot 2 thereof.

Après un léger déplacement relatif des dents 1a, 1b (figure 2B), on voit que les deux points d'appui précédents se sont déplacés, et qu'ils sont maintenant tous les deux des points de contact secondaires, tandis que le point d'appui principal entre les deux roues est maintenant entre l'extrémité 11 de la dent 1c de la première roue, et le pied 2 de la dent suivante 1d de l'autre roue.After a slight relative displacement of the teeth 1a, 1b ( Figure 2B ), we see that the two previous support points have moved, and that they are now both secondary contact points, while the main point of support between the two wheels is now between the end 11 tooth 1c of the first wheel, and foot 2 of the next tooth 1d of the other wheel.

Sur la figure 2C, le point d'appui principal est entre le profil convexe 8 de la roue 1a et le pied 2 de la roue 1a, tandis qu'il y a deux points de contact secondaires entre les deux roues 1b et 1c, respectivement entre le secteur d'extrémité 11 de la dent 1c et le pied d'une nouvelle dent 1d, et entre les deux secteurs convexes 7 des dents 1a et 1c.On the Figure 2C , the main point of support is between the convex profile 8 of the wheel 1a and the foot 2 of the wheel 1a, while there are two secondary contact points between the two wheels 1b and 1c, respectively between the sector d end 11 of the tooth 1c and the foot of a new tooth 1d, and between the two convex sectors 7 of the teeth 1a and 1c.

Sur la figure 2D, le point d'appui principal est entre le secteur convexe 7 de la dent 1c et le point actif de transition 4 de la dent 1d, tandis que la tête de la roue 1c, roule dans la zone de transition des dents 1a et 1d.On the 2D figure , the main point of support is between the convex sector 7 of the tooth 1c and the active transition point 4 of the tooth 1d, while the head of the wheel 1c, rolls in the transition zone of the teeth 1a and 1d.

Le secteur d'extrémité continue de rouler sur le pied 2 de la dent 1a, tandis que l'appui principal est entre le point actif de transition 4 de la dent 1d et le secteur convexe 7 de la dent 1c (figure 2E).The end sector continues to roll on the foot 2 of the tooth 1a, while the main support is between the active transition point 4 of the tooth 1d and the convex sector 7 of the tooth 1c ( figure 2E ).

Enfin, sur la figure 2F, on a retrouvé une situation analogue à la figure 2A, mais cette fois entre les dents 1c et 1d.Finally, on the figure 2F , we found a situation similar to the Figure 2A but this time between teeth 1c and 1d.

Ces figures mettent en évidence une caractéristique importante de l'invention, selon laquelle le premier point de transition 4 d'une dent roule sur le premier secteur convexe 7 d'une dent de la roue opposée. De même, elles mettent en évidence qu'un même point actif d'une dent est successivement un point d'appui principal et un point de contact secondaire au cours de l'engrènement. Enfin, comme indiqué sur les schémas, les dents des deux roues sont en contact sur plus d'un pas de dent, pendant l'engrènement.These figures highlight an important characteristic of the invention, according to which the first point of transition 4 of a tooth rolls on the first convex sector 7 of a tooth of the opposite wheel. Similarly, they show that the same active point of a tooth is successively a main point of support and a secondary point of contact during meshing. Finally, as shown in the diagrams, the teeth of the two wheels are in contact on more than one tooth pitch, during meshing.

La figure 3A montre l'augmentation très importante du volume d'entredent déplacé par rapport à une dent classique en développante de cercle, grâce à l'allongement de la hauteur de la dent et à l'augmentation de l'intervalle entre les dents.The figure 3A shows the very large increase in the amount of displaced entrence compared to a conventional tooth in involute circle, thanks to the lengthening of the height of the tooth and the increase of the interval between the teeth.

La figure 3B est une figure de principe, où l'on peut voir les différentes trajectoires de plusieurs points du profil de dent proposé par l'invention, dans l'entredent du pignon conjugué, avec un effet épicycloïdal allongé prononcé, permettant le fort développement du volume déplacé.The figure 3B is a figure of principle, where one can see the different trajectories of several points of the tooth profile proposed by the invention, in the entrance of the conjugated pinion, with a pronounced elongated epicyclic effect, allowing the strong development of the displaced volume. .

En conclusion, il faut souligner que le profil de dent proposé par l'invention a la particularité de combiner des tronçons en développante de cercle dont les avantages sont déjà connus, avec des tronçons de roulement à profil spéciaux. Cette combinaison assure simultanément une continuité d'engrènement et une conduite de denture suffisante et un très fort développement du volume d'huile déplacé. Le profil de dent proposé par l'invention permet en particulier un gain de débit, notamment à faible vitesse, de l'ordre de 30% à 40%, par rapport à une denture de pompe classique à développante de cercle.In conclusion, it should be emphasized that the tooth profile proposed by the invention has the particularity of combining sections in involute circle whose advantages are already known, with special profile bearing sections. This combination simultaneously ensures a continuity of meshing and a sufficient dentition and a very strong development of the displaced volume of oil. The tooth profile proposed by the invention allows in particular a flow rate gain, especially at a low speed, of the order of 30% to 40%, with respect to a conventional involute pump gearing.

Claims (12)

  1. Gear tooth (1) having a concave root (2) joined at its origin to the root of the adjacent tooth, and a head (3) joined to the said root (2) by a first transition point (4), characterized in that the head of the tooth has two convex sectors (7, 8) situated on the same flank of the tooth and joined by a second transition point (9) marking a discontinuity of curvature on the profile of the tooth.
  2. Gear tooth according to Claim 1, characterized in that the second transition point (9) delimits the bottom of a notch inscribed in the profile of the tooth.
  3. Gear tooth according to Claim 1 or 2, characterized in that the convex sector (7) following the first transition point (4) has an involute profile.
  4. Gear tooth according to Claim 1, 2 or 3, characterized in that the convex sector (8) following the second transition point (9) has an involute profile.
  5. Gear tooth according to one of Claims 1 to 4, characterized in that the head of the tooth (2) has a rounded end sector (11) connected to the second convex sector by a transition sector (12).
  6. External gear pump comprising at least one pair of mutually meshed toothed pinions, each tooth of which is as set forth in one of the preceding claims.
  7. Gear pump according to Claim 6, characterized in that the two toothed wheels are identical.
  8. Gear pump according to Claim 6 or 7, characterized in that the first transition point (4) of a tooth rolls along the first convex sector (7) of a tooth of the opposite wheel.
  9. Gear pump according to Claim 6, 7 or 8, characterized in that there is shape correspondence between the end sector (11) of the teeth and the concave sector defined by the juxtaposition of two roots (2) of adjacent teeth.
  10. Gear pump according to one of Claims 6 to 9, characterized in that the end sector (11) of one tooth rolls between two teeth of the opposite wheel while maintaining contact with them until it escapes from them.
  11. Gear pump according to one of Claims 6 to 10, characterized in that the meshed teeth permanently have at least one main bearing point and one secondary contact point, making it possible to eliminate operational backlash and ensure continuity of meshing.
  12. Gear pump according to one of Claims 6 to 11, characterized in that the teeth of the two wheels are in contact over more than one pitch.
EP04785984A 2003-08-20 2004-07-21 Gear tooth and external gear pump Expired - Lifetime EP1658437B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0310040A FR2859000B1 (en) 2003-08-20 2003-08-20 GEAR TOOTH AND EXTERNAL GEAR PUMP
PCT/FR2004/001925 WO2005021972A1 (en) 2003-08-20 2004-07-21 Gear tooth and external gear pump

Publications (2)

Publication Number Publication Date
EP1658437A1 EP1658437A1 (en) 2006-05-24
EP1658437B1 true EP1658437B1 (en) 2008-06-25

Family

ID=34112826

Family Applications (1)

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EP04785984A Expired - Lifetime EP1658437B1 (en) 2003-08-20 2004-07-21 Gear tooth and external gear pump

Country Status (8)

Country Link
US (1) US8109748B2 (en)
EP (1) EP1658437B1 (en)
JP (1) JP4936888B2 (en)
AT (1) ATE399266T1 (en)
DE (1) DE602004014625D1 (en)
ES (1) ES2305859T3 (en)
FR (1) FR2859000B1 (en)
WO (1) WO2005021972A1 (en)

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US8887592B2 (en) 2011-05-09 2014-11-18 Exponential Technologies, Inc. Spherical involute gear coupling
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Also Published As

Publication number Publication date
FR2859000B1 (en) 2005-09-30
WO2005021972A1 (en) 2005-03-10
US20070274853A1 (en) 2007-11-29
JP2007502950A (en) 2007-02-15
JP4936888B2 (en) 2012-05-23
EP1658437A1 (en) 2006-05-24
US8109748B2 (en) 2012-02-07
FR2859000A1 (en) 2005-02-25
ES2305859T3 (en) 2008-11-01
ATE399266T1 (en) 2008-07-15
DE602004014625D1 (en) 2008-08-07

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