MXPA01000555A - Belt tensioner and method of installing the same - Google Patents

Abstract

A belt tensioner for tensioning a belt for a motor vehicle comprises a pivot shaft (16), a pivoting structure (14) mounted for pivotal movement on the pivot shaft (16), and a pulley (12) mounted for rotation on the pivoting structure. A spring (18) biases the pivoting structure in a direction that moves the pulley mounted on the pivoting structure into tensioning engagement with the belt. A bolt (32) is constructed and arranged to mount the belt tensioner on the motor vehicle engine mount. The bolt (32) is constructed and arranged to be tightened to predetermined exent for installing the tensioner of the motor vehicle, the predetermined extent is the same extent to which the bolt is tightened during normal operation of the tensioner. A clamping structure (24, 36) applies a predetermined clamping force on the pivot shaft after the bolt is tightened to the predetermined extent. The predetermined clamping force is sufficiently large to maintain the pivot shaft in perpendicular relation to the engine mount and prevent tilting of the pivot shaft when the tensioner is moved into installed tensioning engagement with the belt, yet sufficiently small to permit manual movement of the pivot shaft relative to the mounting bolt for adjusting the amount of tension applied by the tensioner to the belt.

Description

BELT TENSIONER AND INSTALLATION METHOD OF THE SAME FIELD OF THE INVENTION The present invention relates to a belt tensioner for an automotive engine and to a method for mounting the same.

BACKGROUND OF THE INVENTION Belt tensioners, such as the tensioners described in US Patent No. 4,824,421, entitled "Belt Tensioner with Releasable Belt Loads", incorporated herein by reference, are mounted directly on the engine block. vehicle. The standard procedure for installing these tensioners is that of tightening the mounting bolt until hand tightening, orienting the belt around the tensioner, adjusting the position of the tensioner arm relative to the nominal position, so that the tensioner is in the coupling. tension REF. : 125685 with the belt, and then fully tighten the mounting bolt. The common procedure for mounting the belt tensioners is not always satisfactory for a number of reasons. First, the tightening of the mounting bolt after adjusting the tension arm causes the movement of the pivot shaft thereby reducing the accuracy of the adjusted position of the tensioner and therefore the preload of the tensioner. Second, the mounting bolt is not fully tightened when the tensioner initially moves to enter the desired tension coupling, with the belt, and therefore the bolt will tilt under the force of the belt. When the mounting bolt is tightened, it will move to be completely perpendicular to the mounting surface of the motor, altering the desired static tension that the tensioner applies to the belt. Third, when removing the tensioner for repair or replacement, the belt load will act on the tensioner when the mounting bolt is removed, resulting in damage to the screw threads of the mounting hole in the tensioner assembly.

BRIEF DESCRIPTION OF THE INVENTION The disadvantages of the prior art can be overcome by providing a belt tensioner for an automotive engine, wherein the pivot shaft of the tensioner is mounted in such a way that it is mounted firmly on the engine without tilting, before and during adjustment of the installation and during normal operation of the engine. In addition, the pivot shaft of the tensioner can be adjusted manually during installation, in order to allow proper tensioning of the belt. The present invention also provides a method for mounting a tensioner, by which the tensioner is firmly mounted to the engine before adjustment, for pre-tensioning the tensioner and entering tension engagement with the belt. According to one aspect of the invention, a tensioner, a stepped mounting bolt and a spring washer are provided. The mounting bolt is inserted through the spring washer and then inserted through the tensioner and tightly tightened a predetermined amount to hold the tensioner to a mounting surface of the tensioner. The deviation of the spring washer produces a predetermined, frictional torque-resistant force that secures the tensioner in place before adjustment and during normal operation of the motor, while allowing a limited amount of rotation of the pivot axis, nominally deflect the tensioner against the toothed belt. According to another aspect of the invention, there is provided a belt tensioner, for tensioning a belt for a motor vehicle, comprising a pivot shaft, a pivoting structure mounted for the pivot movement on the pivot shaft, and a pulley mounted for rotation on the pivoting structure. A spring biases the pivoting structure in a direction that moves the pulley mounted on the pivoting structure so that it comes into tension engagement with the belt. A bolt is constructed and placed to mount the belt tensioner on the motor vehicle engine assembly. The bolt is constructed and accommodated to be tightened to a predetermined degree and to install the motorized vehicle tensioner. The predetermined degree is the same degree to which the bolt is tightened during normal operation of the tensioner. A clamping structure applies a predetermined clamping force on the pivot shaft after the bolt is tightened to the predetermined degree. The predetermined clamping force is large enough to maintain the pivot axis in perpendicular relation to the motor assembly and prevent the tilting of the pivot shaft when the tensioner moves towards the tension couplinginstalled, with the belt, but small enough to allow manual movement of the pivot shaft relative to the mounting bolt, to adjust the amount of tension applied by the tensioner to the belt. A further aspect of the invention relates to a belt tensioner wherein the bolt comprises a shoulder which limits the tightening of the bolt to a predetermined degree. A further aspect of the invention relates to a method for installing a belt tensioner for tensioning a belt for a motor vehicle. The method comprises a pivot shaft and a pivoting structure mounted for pivotal movement on the pivot shaft. A pulley is mounted for rotation on the pivoting structure with a spring that deflects the pivoting structure in a direction that moves the pulley mounted on the pivoting structure so that it enters tension engagement with the belt. A bolt is constructed and positioned to mount the belt tensioner on the motor vehicle engine assembly; and a fixing structure. The method further comprises mounting the tensioner on the engine of the motor vehicle with the bolt; tighten the bolt in such a way that the fastening structure applies a predetermined clamping force on the pivot axis, predetermined clamping force that is sufficiently large to maintain the pivot axis in perpendicular relation to the motor assembly and prevent tilting of the pivot shaft when the tensioner moves towards the installed tension coupling, with the belt, but small enough to allow manual movement of the pivot shaft relative to the mounting bolt, to adjust the amount of tension applied by the tensioner to the belt. Other objects and advantages of the present invention will be apparent from the following detailed description and accompanying drawings illustrating the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view of a tensioner incorporating a mounting group of the present invention. Figure 2 is a sectional view of a second embodiment of a tensioner incorporating the assembly group of the present invention; Figure 3 is a top plan view of the tensioner assembly of the embodiment of Figure 2; and Figure 4 is a sectional view of a third embodiment of a tensioner incorporating a mounting group of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, a tensioner 10 of the present invention is illustrated. The tensioner 10 generally comprises a pulley 12 mounted in a bearing on a pivoting arm 14 which is pivotally mounted on a pivot shaft 16. A plastic sleeve bearing 17 between the arm 14 and the pivot shaft 16 reduces the wear of these components during the operation of the tensioner. The arm 14 is also axially mounted between the bearing members 51 and 53. The coil spring 18 is mounted around the pivot shaft 16 and extends between the pivoting arm 14 and the tensioner assembly 20. The tensioner assembly 20 includes, either the engine block, the head, a tensioner mounting bracket or fixed plate with respect to the engine block. One end of spring 18 is fixed relative to mounting 20, the other end engages pivot arm 14 to rotate arm 14 around shaft 16. Bolt 22 extends through pivot shaft 16 to engage with thread to the assembly 20 of the tensioner, mounting the tensioner 10 thereto. A spring washer 24 is mounted between the flange 26 of the bolt head 22 and the upper housing plate 28 of the tensioner 10. Spring washers are well known in the art and are commercially available. The bolt 22 has a shaft 30 with a stepped diameter, which extends from the flange 26 of the head. A first length 32 of the bolt has a diameter that is received by sliding within the central bore of the pivot shaft 16 and has a length that is slightly greater than the thickness of the tensioner 10. A second length 34 of the bolt, which is distal from the flange 26 of the head, is threaded and has a diameter that is smaller than that of the first length 32, thereby presenting a circumferential shoulder 36. The length of the first extension 32 between the shoulder 26 of the head and the shoulder 36 , and the size and tension force of the spring washer 24 are significant factors in the first embodiment of the present invention. The length of the first extension 32 should be dimensioned such that it accommodates the mounting of the tensioner and the spring washer 24, and still allows sufficient space for the spring washer 24 to be partially compressed between the flange 26 of the head and the housing plate 28, so as to provide a predetermined frictional holding force between the housing plate 28 and the pivot shaft 16 to prevent rotation of the pivot shaft 16 during operation of the tensioner after installation . The predetermined force, applied by the spring washer 24 is also sufficient to fix the tensioner in place, such that the pivot axis is held perpendicular to the assembly 20 even after the belt is oriented around the tensioner and the tensioner. pivot shaft 16 is rotated manually, such that the arm rotates to move the pulley 12 to its desired tension coupling with the belt. In other words, the spring 24 applies sufficient force through the tensioner, to prevent tilting of the pivot shaft 16 under the load force of the belt, applied by the belt to the tensioner during installation and operation of the tensioner. In this respect, the annular surface 39 of the bottom of the pivot shaft 16 should be of a sufficiently large diameter to facilitate this function against tilting. Although the predetermined forceApplied by the spring washer, it must be large enough to perform the anti-tilt aspect, mentioned above, of the pivot shaft 16, both during installation and after installation, and to resist undesired rotation of the axle. pivot during the operation of the tensioner, as a result of the loading force of the belt, the predetermined force must be small enough to allow an operator to rotate angularly the pivot shaft 16 around the bolt 22 during the installation of the tensioner, to initially preload the tensioner 10 against the belt. The spring washer 24 is capable of providing the required, predetermined clamping forces and torque-resistant forces, because the belt load of a toothed belt acting through a relatively short arm produces a torque. of relatively low torque on the pivot shaft 16. The shoulder 36 limits the amount of clamping force that can be applied by the spring washer 24 to the predetermined clamping force. To install a tensioner 10, the spring washer 24 is presented to the mounting bolt 22 and the bolt 22 is then inserted through the central bore of the pivot shaft 16. The tensioner 10 is presented to the tensioner assembly 20 by inserting the end 38 of the spring 18 inside a spring receiving bore 40, on the tensioner assembly 20. The bolt 22 of 22 is engaged by screwing with the threaded bore 42, on the tensioner assembly 20. The mounting bolt 22 is fully tightened until the shoulder 36 connects to the tensioner assembly 20. The tightening action will compress the spring washer 24 to a predetermined degree, limited by the shoulder 36 which splices with the assembly 20 to firmly engage the tensioner 10. The tensioner 10 will engage firmly to the tensioner assembly 20 with sufficient force, under the action of the spring 24 to ensure the perpendicularity of the pivot shaft 16 relative to the assembly 20. The pivot shaft 16 is then manually rotated to adjust the angular position thereof (the limited / controlled amount of the clamping force applied by the spring 24 allows this) until the arm 14 reaches a nominal position, preloading the tensioner against the toothed band (not shown). To remove the tensioner 10 the stages are inverted. A further advantage of the present invention is that the load of the belt against the tensioner 10 is removed, allowing the mounting bolt 22 to be removed in an unloaded condition which minimizes the probability of damage to the threads of the threaded bore 42. present invention provides a simple three-stage process to install the tensioner and properly preload the tensioner. In particular, the process of the present invention avoids the step of tightening the post-adjusting bolt, common in the prior art installations, a step that is the source of many of the shortcomings of the prior art. Additionally, the installation process of the present invention allows the tension to the belt, applied by the tensioner, to be adjusted by manually rotating the pivot shaft 16 while the engine is in operation and allowing automated installation. Referring now to Figures 2 and 3, a second embodiment of the tensioner 110 is illustrated. The tensioner 110 has the same corresponding components as the tensioner 10, except that the central bore of the pivot shaft 116 has a widening on the side. lower thereof, to receive the head of the pin 122. The spring washer 124 presses against a snap ring 150 which retains the pin 122 within the spreading in a sliding fit. The tensioner 110 is installed in a similar manner as described above. By tightening the mounting bolt 122, the mounting bolt 122 will engage the spring washer 125, which will elastically couple an inner lip of the pressure ring 150. Simultaneously, the shoulder 136 of the mounting bolt 122 will butt against the tensioner assembly 20 to securely but still elastically, the tensioner 110 at the same. Optionally, a hexagonal shaped opening 152 can be provided in the upper surface of the tensioner 110. A hexagonal wrench could be used to provide mechanical advantage by rotating the pivot shaft 116 against the forces resistant to the friction torque, generated by the deflection of the spring washer 124. This embodiment employs the deflection of the spring washer 124 against the pressure ring 150, and the friction between the pressure ring 150 and the pivot shaft 116 to maintain the perpendicularity of the pivot shaft 116. and preventing unwanted pivoting movement of the pivot shaft 116 around the pin 122 during operation of the tensioner. However, the pivotal, manual movement of the shaft 116 is allowed during adjustment in operation or in the installation, even after the bolt 122 has been fully tightened. In this embodiment, the load force of the belt, applied by the belt against the tensioner, increases the frictional engagement between the pivot shaft 116 and the pressure ring 150. Figure 4 shows a third embodiment of the present invention. This mode is very similar to the first mode, except that a mounting bolt is used in general straight, without any shoulder that joins the assembly 20. Instead, to limit the amount of clamping force applied by the washer of spring 24, a torque wrench having a torque indicator or limit switch is used to tighten the bolt 22 to a predetermined predetermined degree, which will cause the spring washer 24 to apply the predetermined axial clamping force, desired , to the pivot shaft 16. Again, this clamping force will ensure the perpendicularity of the axis 16, prohibits the rotation of the pivot shaft 16 during normal operation of the tensioner, and still allows manual rotation of the pivot shaft 16 during the initial installation or even during the operation of the tensioner to adjust the amount of tension applied to the belt. Although the invention has been described in relation to what is presently considered to be the most practical and preferred modalities, it is understood that the invention is not limited to the described modalities, but, on the contrary, pretends to cover several modifications in the arrangements that are within the scope of the following claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property:

Claims (13)

RE IVINDICATIONS

1. A belt tensioner for tensioning a belt on the engine of a motor vehicle, the belt tensioner is configured to be mounted to a tensioner assembly and characterized in that it comprises: a pivot shaft; a pivoting member pivotally mounted on the pivot shaft; a pulley assembled ro tionally on the pivoting member; a spring configured and positioned in such a way as to deflect the pivoting structure and the pulley, towards the belt, when the tensioner is installed on the tensioner assembly and the belt is installed on the motor of the motor vehicle; a mounting bolt configured and positioned to mount the belt tensioner to the tensioner assembly, the mounting bolt is configured to be tightened in the tensioner assembly, to a predefined degree, when the tensioner is installed on the tensioner assembly; and an elastic fixing member, configured and positioned in order to apply a predetermined clamping force against the pivot shaft after the mounting bolt has been tightened in the tensioner assembly to the predefined degree, the predetermined clamping force sustains the pivot shaft against the tensioner assembly and is large enough to maintain the pivot axis in perpendicular relation to the tensioner assembly, when the tensioner is subjected to belt loads, thereby preventing the tilting of the pivot shaft when the tensioner moves to a tension coupling, installed, with the belt, and the predetermined clamping force is small enough to allow manual rotational movement of the pivot shaft relative to the mounting bolt, in order to adjust the amount of tension applied by the tensioner to the belt.

2. A belt tensioner according to claim 1, characterized in that the predefined degree is the same as the degree to which the mounting bolt is tightened for the normal operation of the tensioner.

3. A belt tensioner according to claim 1, characterized in that the mounting bolt has a shoulder which determines the predefined degree in which the mounting bolt can be tightened in the tensioner assembly.

4. A belt tensioner according to claim 1, characterized in that the clamping member is configured to cooperate with the belt to generate and apply the predetermined clamping force to the pivot shaft.

5. A belt tensioner according to claim 1, characterized in that the fixing member comprises a spring washer and that the amount of force that the spring washer applies against the pivot axis is determined, in part, by the predefined degree in which tightens the mounting bolt in the tensioner assembly.

6. A belt tensioner according to the indication 5, characterized in that the spring washer is placed between a head of the mounting bolt and the pivot shaft.

7. A belt tensioner according to claim 5, characterized in that the spring washer is configured to apply the predetermined clamping force against the pivot axis in an axial direction.

8. A belt tensioner according to the indication 5, characterized in that the spring washer is configured to apply a clamping force against the pivot shaft in a radial direction.

9. A belt tensioner according to claim 8, characterized in that a belt loading force, applied by the belt, causes fixing forces to be created by friction, in the radial direction, whereby the belt cooperates with the belt. fixing member for generating and applying the predetermined clamping force against the pivot axis.

10. A belt tensioner for tensioning a belt on the engine of a motor vehicle, the belt tensioner is configured to be mounted on a tensioner assembly and is characterized in that it comprises: a pivot shaft; a pivoting member pivotally mounted on the pivot shaft; a rotary mounted pulley ent e on the pivot member; a spring configured and positioned in order to deflect the pivoting structure and the pulley, towards the belt, when the tensioner is installed on the tensioner assembly and the belt is installed on the engine of the motor vehicle; a mounting bolt configured and positioned to mount the belt tensioner to the tensioner assembly; and, an elastic restraining member, configured and positioned so as to apply a predetermined clamping force against the pivot shaft after the mounting bolt has been tightened in the tensioner assembly, up to the adjustment of the predetermined torque portion of a wrench For torque, the predetermined holding force holds the pivot shaft against the tensioner assembly and is large enough to maintain the pivot axis in perpendicular relation to the tensioner assembly when the tensioner is subjected to the belt loads, so which prevents tilting of the pivot shaft when the tensioner moves to a tension coupling, installed, with the belt, and the predetermined clamping force is small enough to allow manual rotational movement of the pivot shaft relative to the bolt of assembly, in order to adjust the amount of tension applied by the tensioner to the belt.

11. A method for installing a belt tensioner for tensioning a belt on the motor of a motor vehicle, the belt tensioner comprises a pivot shaft; a pivoting member pivotally mounted on the pivot shaft; a pulley rotationally mounted on the pivoting member; a spring configured and positioned in order to deflect the pivoting structure and the pulley, towards the belt, when the tensioner is installed on the tensioner assembly and the belt is installed on the engine of a motor vehicle; a mounting bolt configured and positioned to mount the belt tensioner on the tensioner assembly; and an elastic fastening member; the method is characterized in that it comprises: placing the tensioner on a tensioner assembly and fastening the tensioner on the tensioner assembly, using the mounting bolt; tighten the mounting bolt until the clamping member applies a predetermined clamping force against the pivot shaft, the predetermined clamping force that holds the pivot shaft against the tensioner assembly and that is large enough to maintain the pivot axis in relation perpendicular to the tensioner assembly when the tensioner is subjected to belt loads, thereby preventing the tilt of the pivot shaft when the tensioner moves in a tension coupling, installed, with the belt, and the clamping force the predetermined is small enough to allow manual rotational movement of the pivot shaft relative to the mounting bolt, in order to adjust the amount of tension applied by the tensioner to the belt; Orient the belt around the tensioner; and then manually adjust the pivot shaft after tightening, to establish a desired level of belt tension.

12. A method according to claim 11, characterized in that the mounting bolt is configured to be tightened in the tensioner assembly to a predefined, limited degree, wherein the predefined, limited degree is such as to cause the fastening member to apply the Forced clamping force, the method comprises tightening the mounting bolt in the tensioner assembly to a predefined, limited degree.

13. A method according to claim 11, the method is characterized in that it comprises tightening the mounting bolt in the tensioner assembly, up to a predetermined torque setting of a key, the predetermined torque adjustment is selected to cause the clamping member generates and applies the predetermined clamping force. SUMMARY OF THE INVENTION A belt tensioner for tensioning a belt for a motor vehicle, comprising a pivot shaft (16), a pivoting structure (14) mounted for pivoting movement on the pivot shaft (16), and a pulley (12) mounted for rotation on the pivoting structure. A spring (18) deflects the pivoting structure in a direction that moves the pulley mounted on the pivoting structure, in tension coupling with the belt. A bolt (32) is constructed and arranged to mount the belt tensioner on the motor vehicle motor assembly. The bolt (32) is constructed and arranged to be tightened to a predetermined degree to install the tensioner of the motor vehicle, the predetermined degree being the same degree to which the bolt is tightened during the normal operation of the tensioner. A support structure (24, 36) applies a predetermined clamping force on the pivot shaft after the bolt is tightened to the predetermined degree. The predetermined clamping force is large enough to keep the pivot axis perpendicular to the motor mounting and prevent deflection of the pivot shaft when the tensioner moves to the tension coupling, installed, with the belt, but small enough to allow manual movement of the pivot shaft relative to the mounting bolt, to adjust the amount of tension applied by the tensioner to the belt.