EP2053248A2 - Belt drive mechanism and its manufacturing method - Google Patents

Abstract

The mechanism has a mount (10) defining a geometric reference plane (34) and provided with a strut (16) making projection perpendicular to the reference geometric plane. A shaft (30) traverses the strut and the geometric reference plane. A pulley drum is provided with a tread to cooperate with a driving belt and a face (66) axially supporting against a sub-assembly. A fixation stud (68) fixes the drum to the sub-assembly, and is arranged parallel to a geometric rotation axis (26), and a rotating unit e.g. blade wheel (36), is integrated to a shaft and located in a side of the reference plane. An independent claim is also included for a method for assembling of a driving mechanism.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to a belt drive mechanism, and in particular, although in a non-limiting manner, to a mechanism for driving with a belt a water pump wheel of a motor vehicle.

STATE OF THE PRIOR ART

In the document FR 2.160.201 is described a cooling water pump for a motor vehicle engine. This pump has a paddle wheel disposed on one side of a housing member forming, on the opposite side of the impeller, an outwardly projecting barrel forming a seat for an inner race ring. The impeller is integral with a shaft section which extends from the casing at the barrel and which is connected to a pulley rim via a radial arm. On the rim is mounted an outer race, the inner and outer rings forming a bearing located axially between the impeller on the one hand and the radial connecting arm on the other. The arm is attached to the shaft by welding. As a result, the pump forms with the housing element a unitary subassembly. However, the assembly of this sub-assembly is complex because the welding of the shaft section to the arm of the pulley must be done once the bearing has been mounted. In particular, the axial alignment between the impeller and the pulley is difficult to meet during assembly. Furthermore, the arm is approximately in a median radial plane of the rim and the bearing is confined in axial end of the rim. There is room for only one row of logs, even though part of the pulley is cantilevered. The torque resulting from the forces applied by the belt to the pulley tends to misalign the pulley and with it the shaft section and the impeller. Moreover, the cumulative thickness of the pulley rim and the outer ring limits the space available for the balls of the bearing. For all these reasons, the loads that can support this device are limited.

In the document EP 0 289 958 a cooling water pump for a motor vehicle engine comprising a paddle wheel mounted on one side of a casing element, at the end of a shaft integral with a pulley rim located other side of the housing element. The pulley is guided by a rolling bearing. The outer race of the bearing is formed directly inside the pulley rim. The inner raceway is formed on an axle section mounted on a flange integral with the pump housing. The pulley rim is located between the housing member and the flange, which increases the axial and radial dimensions of the device. In addition, the alignment of parts is very imperfect, which requires to take precautions at the seals between the shaft and the housing element.

In the document US 6,200,089 is described a cooling circuit pump of an internal combustion engine driven by a toothed belt. The impeller of the pump is attached to a shaft that passes through the cooling system housing. A pulley is fitted at the end of the shaft. A two-row ball bearing ensures guiding of the shaft and the pulley. This bearing comprises a pair of inner rings fixed to the housing and a pair of outer rings attached to the pulley. This compact device poses a problem of assembly logistics, since the pulley must pass successively from the pulley manufacturer to the rolling mill then to the pump manufacturer and finally to the vehicle manufacturer. In addition the pulley described is necessarily heavy, complex and expensive. Finally, it does not lend itself to modular construction and standardization of parts.

In the document US 3,934,966 is also described a drive device of a cooling pump and a fan attached to a common shaft via a pulley. The pulley is keyed at the end of the shaft and the fan propeller is screwed onto the body of the pulley. The assembly is supported by a bearing whose inner ring is fixed to the pump casing and the outer ring is fixed to the body of the pulley. The body of the pulley is particularly complex and heavy.

STATEMENT OF THE INVENTION

The invention aims to overcome the disadvantages of the state of the art, so as to provide a mechanism which is easy to mount and increased modularity without sacrificing performance.

• un bâti définissant un plan géométrique de référence et pourvu d'un fût faisant saillie perpendiculairement au plan géométrique de référence ;
• un sous-ensemble comportant:
  • un roulement situé entièrement d'un premier côté du plan géométrique de référence, définissant un axe géométrique de rotation perpendiculaire au plan géométrique de référence et comportant: une bague de roulement intérieure fixée au fût et sur laquelle est formé au moins un chemin de roulement intérieur ; une bague extérieure sur laquelle est formé au moins un chemin de roulement extérieur situé en regard du chemin de roulement intérieur ; et des corps roulants disposés sur les chemins de roulement ;
  • un arbre traversant le fût et le plan géométrique de référence ; et
  • des moyens de liaison de l'arbre à la bague extérieure, s'étendant radialement entre l'arbre et la bague extérieure, et tangents à un deuxième plan géométrique qui est perpendiculaire à l'axe de rotation et est situé à plus grande distance du plan transversal de référence que les chemins de roulement;
• un tambour de poulie pourvu d'une bande de roulement pour coopérer avec une courroie d'entraînement et d'une portée en appui axial contre le sous-ensemble, et
• des goujons de fixation du tambour au sous-ensemble, disposés parallèlement à l'axe géométrique de rotation
• un organe tournant solidaire de l'arbre et situé d'un deuxième côté du plan géométrique de référence.

For this purpose, and according to a first aspect of the invention, the subject of the invention is a drive mechanism comprising:

• a frame defining a geometric reference plane and provided with a barrel projecting perpendicular to the reference geometric plane;
• a subset comprising:
  • a bearing located entirely on a first side of the reference geometrical plane, defining a geometric axis of rotation perpendicular to the reference geometrical plane and comprising: an inner race fixed to the shaft and on which at least one inner race is formed ; an outer ring on which is formed at least one outer race located opposite the inner raceway; and rolling bodies arranged on the raceways;
  • a tree crossing the barrel and the geometric reference plane; and
  • means for connecting the shaft to the outer ring, extending radially between the shaft and the outer ring, and tangential to a second geometrical plane which is perpendicular to the axis of rotation and is located at a greater distance from the transverse plane of reference as the raceways;
• a pulley drum provided with a tread to cooperate with a drive belt and a bearing bearing axially against the subassembly, and
• studs for fixing the drum to the subassembly, arranged parallel to the geometric axis of rotation
• a rotating member secured to the shaft and located on a second side of the reference geometrical plane.

The drum being distinct from the outer ring, it incorporates fewer functions, which simplifies its manufacture. The studs allow a very simple attachment of the pulley drum after mounting the shaft on the frame via the bearing. We can also standardize the subassembly for different sizes of pulley and rotating member. The term "dowel" means any type of fixing rod, threaded or not, with or without a head, cooperating or not with an auxiliary fastening member such as a nut.

Advantageously, the rods can cross the second geometric plane. According to one embodiment, the drum comprises a flange tangent to the second geometric plane and bearing against the connecting means, the threaded rods cooperating with the connecting means and with the flange. Alternatively, the outer ring may comprise bores cooperating with the securing rods.

According to one embodiment, the connecting means comprise at least one assembly interface with the outer ring, located at a greater distance from the transverse plane than the raceways. The positioning of the interface facilitates assembly. Preferably, the distance between the assembly interface and the axis of rotation is greater than the pitch diameter of the bearing. The circumference of the interface is therefore important, which further contributes to facilitating the assembly. The mounting of the rolling elements, in particular the rolling bodies, but also, where appropriate, the cage and seals, is also facilitated.

The connection of the connecting means to the outer ring can be achieved in different ways, including crimping, hooping, welding, gluing or stapling.

Alternatively or complementary to the assembly interface described above, the connecting means may comprise an assembly interface with the shaft, located at a distance from the axis of rotation less than the inside diameter of the barrel. Because of its small diameter, the assembly interface with the shaft does not hinder the insertion of the shaft into the barrel. Preferably, the connecting means comprise a sleeve assembled to the shaft by fitting.

According to one embodiment, the connecting means comprise at least one intermediate piece assembled to the shaft and to the outer ring. Preferably, the connecting means consist of a flange assembled to the shaft and to the outer ring. This flange may advantageously be made of aluminum or stamped steel, provided with punctured for the establishment of the fastening rods.

Alternatively, it is possible to provide a subset formed of the shaft and connecting means, subassembly which is fixed on the outer ring. Alternatively, it would also be possible to provide a subset consisting of the outer ring and connecting means, which is fixed on the shaft.

Preferably, the barrel carries an inner ring on which is formed the inner raceway. Advantageously, this ring may have a radial plane of symmetry, which allows to mount without worrying about its orientation. Alternatively, it can be provided that the inner raceway is formed directly on the shaft. We can then optimize the thicknesses of the drum and drum, and if necessary increase the size of the balls.

Preferably, the barrel carries two coaxial inner raceways, the outer race being provided with two outer raceways located facing the two inner raceways, forming with the rolling bodies a rolling bearing with two rows of rolling bodies. This considerably increases the load that can be supported by the mechanism and the power that it can transmit. Advantageously, the load lines of the rolling bodies of the two rows of rolling bodies are inclined with respect to a radial plane, which gives a greater axial stability to the rolling. The outer ring is advantageously a single piece with two raceways, as well as the inner ring.

Preferably, the rolling bodies are balls, although cylindrical or conical rollers or needles are possible.

Advantageously, the range of the drum may be provided with a centering relief cooperating for example with the outer ring, with the connecting means or with the shaft for centering the drum relative to the axis of rotation of the subassembly.

According to another aspect of the invention, it relates to a water pump provided with a mechanism as described above whose rotating member is a paddle wheel.

The rotating member may, however, be any type of receiving member or motor, the drive mechanism of the invention being able to transmit power both from the belt to the shaft and from the shaft to the belt.

BRIEF DESCRIPTION OF THE FIGURES

• les figures 1A à 1D, un mécanisme d'entraînement à poulie selon un premier mode de réalisation de l'invention, de face, de côté, en perspective et en coupe axiale ;
• les figures 2A à 2D, un mécanisme d'entraînement à poulie selon un deuxième mode de réalisation de l'invention, de face, de côté, en perspective et en coupe axiale ;
• les figures 3A à 3D, un mécanisme d'entraînement à poulie selon un troisième mode de réalisation de l'invention, de face, de côté, en perspective et en coupe axiale ;
• les figures 4A à 4D, un mécanisme d'entraînement à poulie selon un quatrième mode de réalisation de l'invention, de face, de côté, en perspective et en coupe axiale;
• les figures 5A à 5D, un sous-ensemble du mécanisme des figures 4A à 4D, de face, de côté, en perspective et en coupe axiale.

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of non-limiting examples, with reference to the appended figures which respectively illustrate:

• the Figures 1A to 1D a pulley drive mechanism according to a first embodiment of the invention, from the front, from the side, in perspective and in axial section;
• the Figures 2A to 2D a pulley drive mechanism according to a second embodiment of the invention, from the front, from the side, in perspective and in axial section;
• the Figures 3A to 3D , a pulley drive mechanism according to a third embodiment of the invention, from the front, from the side, in perspective and in axial section;
• the Figures 4A to 4D , a pulley drive mechanism according to a fourth embodiment of the invention, from the front, from the side, in perspective and in axial section;
• the Figures 5A to 5D , a subset of the mechanism of Figures 4A to 4D , from the front, from the side, in perspective and in axial section.

To simplify the presentation, the elements common to the different embodiments will be designated by the same reference signs and their description will not be systematically repeated.

DETAILED DESCRIPTION OF AN EMBODIMENT

With reference to Figures 1A to 1D , a frame 10 constituting a coolant circuit casing is provided with a barrel 16 forming a cylindrical bearing surface 18 for an inner ring 20 of a bearing 22. The ring 20 is provided with two raceways 24 which define a geometric axis of rotation 26 of the mechanism. The drum 16 also defines an axial opening 28 allowing the passage of a shaft 30. A dynamic seal 32 provides a seal between the shaft 30 and the frame 10, so as to prevent leakage of liquid through the opening. The frame 10 constitutes a fixed element which makes it possible to define a reference radial geometric plane 34 traversed by the shaft 30. At one end of the shaft 30, on the left side of the plane on the figure 1D , is fitted a paddle wheel 36 (which has not been shown on the Figures 1A to 1C ). At the other end of the tree, on the right side of the reference plane on the figure 1D , is fitted a massive plate 40 which extends radially outwardly and is provided with an end flange 42. The plate is perforated by openings 44 distributed on its surface. The edge 42 of the plate is fitted on a cylindrical seat inner 46 of a one-piece outer ring 48 of the bearing 22, so that the flange 40 constitutes a mechanical connecting member between the shaft 30 the outer ring 48.

The outer ring 48, consisting of a steel piece, is located entirely on the reference plane side 34 opposite to the impeller. The outer ring 48 defines an opening in which the barrel 16 is inserted and forms two outer raceways 54 situated opposite the raceways 24 of the inner race 20. These raceways 24, 54 make it possible to house two rows of balls. 56. The bearing thus formed is protected from the outside by two annular seals 60, mounted on the outer ring on either side of the raceways 24, 54 and rubbing on the inner ring 20. The lines load balls of the two rows are preferably inclined relative to a radial plane, and intersect the axis of rotation at two points in two radial planes that frame the raceways.

A pulley drum 62 is fixed to the plate 40. This drum comprises a tread 64 with a radial sawtooth profile. It is further provided with a cup 66 which bears on the plate 40. The attachment is provided by axial threaded studs 68 passing through bores 70, 71 provided in the plate and in the cup. The studs 66 are provided with a head received in a recess of the plate and the clamping of the pieces is obtained by means of nuts 72, one of which has been shown on the figure 1D . The cup 66 is also provided with a centering hole 76 in which is housed the end of the shaft 30.

The assembly of the mechanism of Figure 1A to 1D is particularly simple. The bearing 22, consisting of the inner ring 20, the outer ring 48, possibly cages (not shown), the two rows of balls 56 and the two seals 60 is mounted in a first step. This arrangement is facilitated by the fact that the outer ring 48 is widely open at both ends, the bearing 46 having a larger diameter than the pitch diameter of the two rows of balls, and even larger than the inside diameter of the raceways 54. Then the inner ring 20 is fitted on the barrel 16. The subassembly consisting of the shaft 30 and the cup 40 can then be fitted on the interface formed by the inner cylindrical bearing surface 46 of the outer ring 48 and the impeller 36 is fitted to the end of the shaft 30. Finally, the end of the shaft 30 is inserted into the centering hole 76 before securing the drum 62 by means of the nuts 72. As can be seen in FIG. figure 1D , the raceways 24, 54 are located between the reference plane 34 and a radial plane 74 tangential to the cup, the tread running axially on either side of the raceways.

On the Figures 2A to 2D is shown a second embodiment of the invention, which differs from the previous in that the connection between the shaft 30 and the outer ring is constituted by a cup 140 made by stamping a sheet and having a sleeve 142 fitted on the shaft and an outer skirt 144 on which is crimped the outer ring 48. The cup is further provided with punctures 146 which allow the insertion of the pulley drum threaded studs, which are here screws screwing directly into a thread provided in the crevices.

The assembly of the device Figures 2A-2D is similar to that of the first embodiment. Firstly, the bearing 22 is assembled on the one hand and the cup on the other hand is fitted onto the shaft. Then we crimp or fret the cup on the outer ring to form the subset. Finally, this subassembly can be assembled on the frame and the impeller (not shown) and the pulley drum can be fixed.

On the Figures 3A to 3D is shown a third embodiment of the invention, which differs from the previous in that the shaft flares to form a flange 240 which allows a connection by hooping or crimping to the outer ring 48 of the bearing. The flange is provided with threaded holes 242 which allow the screwing of bolts 68 for fixing the pulley drum.

The assembly method is simplified here since the step of mounting the shaft on the connection means is eliminated.

On the Figures 4A to 4D and 5A to 5D is shown a fourth embodiment of the invention, which differs from the previous in that the drum 62 is attached directly to the outer ring 48. The outer ring 48, visible in detail on the Figures 5A to 5D is in fact provided with three ears 480 equispaced at its periphery and each pierced with a bore 482. The outer ring further comprises a cylindrical centering surface 484. As illustrated by Figures 4A to 4A , the drum 62 is provided with a centering hole 462 cooperating with the bearing 484 to ensure the respective positioning of the parts. The bores 482 of the outer ring allow the fixing of the pulley drum 62 which, unlike the previous embodiments, bears axially directly on the lugs 48. Moreover, the outer ring is connected to the shaft 30 by through a cup 440. The cup is provided with a central opening 442 for passage of the shaft 30. The end of the shaft is deformed in a crimping operation to form a groove 430 for fixing the cup. The cup is also provided with an outer skirt 444 which is engaged in the outer ring 48.

The mechanism of assembly of the mechanism of Figures 4A-5D is analogous to what has been described previously.

Naturally, various modifications are possible.

The tread may have any shape suitable for a drive belt, for example a frustoconical shape or with several truncated cones. It may be optionally provided with ridges or other reliefs ensuring better cooperation with the belt. The term belt used throughout the application must be understood generically to include any type of endless flexible link, of any section.

The invention is not limited to water pumps, the impeller may be replaced by any type of receiving member to be secured to a pulley driven by a belt. The impeller can also be replaced by a drive member driving the shaft and the pulley drum, and for driving the belt.

The order of assembly operations can be changed as needed. In certain circumstances, it may be preferable to mount the shaft on the bearing before mounting the bearing to the frame. In other circumstances, these operations may be reversed.

The connection means between the shaft and the drum can be of any type ensuring the transmission of torque, for example spokes or arms. Fixing these means of connection to the drum can be done by any means, including crimping, fitting hot or cold, gluing or welding. The interface between the outer ring and the connecting means may be smooth or provided with reliefs, for example flutings.

The studs can be in one piece with the connecting means or with the drum.

Those skilled in the art will furthermore be able to combine the various embodiments with one another in order to constitute other variants.

Claims (15)

Drive mechanism comprising: - a frame (10) defining a reference geometric plane (34) and provided with a shaft (16) projecting perpendicularly to the reference geometric plane; a subset comprising: a bearing (22) located entirely on a first side of the reference geometrical plane, defining a geometrical axis of rotation (26) perpendicular to the reference geometrical plane and comprising: an inner bearing ring fixed to the barrel and on which is formed at least one inner race (24); an outer race (48) on which is formed at least one outer raceway (54) facing the inner race (24); and rolling bodies (56) disposed on the raceways (22); - a shaft (30) passing through the barrel and the geometric reference plane; and - connection means (40) of the shaft to the outer ring, extending radially between the shaft and the outer ring, and tangent to a second geometric plane (74) which is perpendicular to the axis of rotation ( 26) and is located at a greater distance from the reference transverse plane than the rolling tracks, the connecting means comprising: at least one assembly interface (46) with the outer ring located at a greater distance from the reference transverse plane than the raceways, and at least one assembly interface (142, 442) with the shaft located at a distance from the axis of rotation less than the inside diameter of the barrel; a pulley drum provided with a tread (50) to cooperate with a drive belt and a bearing surface (66) bearing axially against the subassembly, and - bolts (68) for fixing the drum to the subassembly, arranged parallel to the geometric axis of rotation - A rotating member (36) integral with the shaft and located on a second side of the reference geometric plane. Mechanism according to claim 1, wherein the studs pass through the second geometric plane. Mechanism according to any one of claims 1 or 2, wherein the scope is tangent to the second geometric plane. Mechanism according to any one of the preceding claims, wherein the bearing bears against the connecting means. A mechanism according to any one of the preceding claims, wherein the drum is provided with a cup (66) forming the bearing and having fixing bores (71), the studs passing through the fixing bores. Mechanism according to any one of the preceding claims, wherein the outer ring comprises bores (482) cooperating with the fixing studs. Drive mechanism according to any one of the preceding claims, wherein the tread is located between the reference geometrical plane and the second geometrical plane. The mechanism of claim 7, wherein the distance between the assembly interface with the shaft (46) and the axis of rotation is greater than the pitch diameter of the bearing. Drive mechanism according to claim 8, wherein the connecting means are assembled to the outer ring by crimping, hooping, welding, gluing or stapling. Mechanism according to any one of the preceding claims, wherein the connecting means comprise a sleeve (142) assembled to the shaft by fitting. Mechanism according to one of the preceding claims, wherein the connecting means are constituted either by a flange (40) of constant sensitive axial thickness assembled to the shaft and the drum, or by a cup (140) stamped provided with punctured (146) for the passage of the studs. Drive mechanism according to any one of the preceding claims, wherein the load lines (62) of the rolling bodies of the two rows of rolling bodies are inclined with respect to the reference plane. Motor vehicle water pump, provided with a drive mechanism according to any one of the preceding claims, the rotating member being constituted by a impeller (36). A method of assembling a mechanism according to any one of claims 1 to 13, comprising a step of pre-assembly of the subassembly, followed by a step of fixing the drum (62) to the subassembly. An assembly method according to claim 14, further comprising a step of mounting the subassembly on the frame (10), followed by a step of mounting the rotating member (36) on the shaft, the step fixing the drum being preferably subsequent to the mounting step of the subassembly on the frame.

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