Improper working position detection for tire mounting apparatus and method

An apparatus for mounting a tire on a wheel rim includes a mounting head with a tire bead deflector and a tire press-in roller, and a drive that moves the mounting head toward, and rotates the bead deflector and the press-in roller around, the wheel rim. To avoid a damage-causing contact between the bead deflector and the wheel rim, an arrangement for monitoring a minimum spacing distance between the wheel rim and the mounting head is arranged preferably on the bead deflector. If an improper working position closer than the minimum spacing distance is detected, the arrangement produces a signal that influences, e.g. stops, the motion of the mounting head. The arrangement preferably includes a contact member of a comparatively soft low-friction material at a working end of the bead deflector. If the contact member contacts the wheel rim, this actuates a piezoelectric element to generate the required electrical signal.

PRIORITY CLAIM

This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 10 2004 040 866.1, filed on Aug. 23, 2004, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a method and an apparatus for mounting a tire onto a rim of a vehicle wheel, using a tire mounting head with a bead deflector and a press-in roller as well as a drive for rotating the mounting head about the wheel rim axis and for axially moving the mounting head.

BACKGROUND INFORMATION

A tire mounting apparatus and method of the above mentioned general type are known from the company catalog “Balancing and Diagnostic Systems”, 2002 Catalog RA 1020e of the company Schenck RoTec GmbH, of Landwehrstrasse 55, D-64293 Darmstadt, Germany. At pages 116 and 117, the English version of the mentioned catalog discloses a tire mounting or assembly machine for vehicle wheels, whereby the tire is at first laid sloping obliquely onto the wheel rim of a vehicle wheel to begin the tire mounting process. The lower tire bead of the tire is partly located within the recessed deep well of the rim, and partly protrudes outwardly above the upper rim flange. To carry out the tire mounting process, the wheel rim is supported and tightly held or clamped, and the tire mounting head (also called a draw-down head or pull-on head) is lowered until the bead deflector and the press-in or press-down roller contact the side of the tire. Then the mounting head is rotated about the rim axis. The bead deflector pushes against and along the tire bead to ensure that the tire bead lies radially outwardly relative to the rim flange, and then the following press-in roller axially presses the tire bead downwardly into the deep recessed well of the wheel rim, while simultaneously the lower tire bead is pressed into contact against the lower rim flange. The mounting of the two tire beads onto the rim can be carried out, as desired, either together in common in one operation, or sequentially in two rotations of the mounting head. The mounting head is adjustable to various different wheel rim types, e.g. different rim diameters, rim widths, or rim profiles or shapes. The adjustment can be achieved automatically in connection with a preceding rim type recognition.

In practice, it has been found that the rim type recognition can give incorrect rim type identifying data, for example due to a malfunction or various type-recognition errors. Errors can also arise due to interference in the transmission of the type identifying data from the type recognition arrangement to the tire mounting apparatus. Still further errors can arise during the automatic or manual adjustment of the bead deflector and/or the press-in roller, as well as the drive movements of the mounting head. If the wheel rim is clamped on the rim support in an uncentered or tilted manner, it gives rise to further positioning errors.

The above mentioned errors can cause an improper working position of the bead defector and/or the press-in roller relative to the particular wheel rim being processed. In a worst case situation, such improper working position can cause the bead deflector to collide with, gouge into, or scrape along the wheel rim flange, or excessively deflect the tire bead, and thereby damage the wheel rim and/or the tire. Since the contact of the bead deflector with the wheel rim flange occurs on the visible decorative side of wheel rim, even the slightest visible damage leads to rejection of the wheel rim, or damage of the tire leads to rejection of the mounted tire-rim combination, in subsequent quality control. Furthermore, any damage to the rim flange or the tire bead can make it impossible to properly and successfully mount the tire on the rim. The equipment itself, e.g. the bead deflector, can also become damaged by improperly contacting and pressing against the rim flange.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the invention to improve a tire mounting apparatus and method of the above mentioned general type in such a manner so as to ensure the trouble free performance of the tire mounting process, even for a succession of wheel rims of different types or sizes. A further object of the invention is to avoid damage to the tire, rim or equipment due to an improper working position and especially contact between the bead deflector and the wheel rim flange. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification. The attainment of these objects is, however, not a required limitation of the claimed invention.

The above objects have been achieved according to the invention in an apparatus for mounting a tire on a wheel rim of a vehicle wheel, comprising a wheel rim support, a tire mounting head and a drive arrangement. The wheel rim support supports the wheel rim. The tire mounting head includes a tire bead deflector that deflects a tire bead of the tire around a wheel rim flange of the wheel rim, and a tire press-in roller that presses the tire bead into a rim well of the wheel rim. The drive arrangement is connected to the tire mounting head and drives the tire mounting head rotationally about a wheel rim axis of the wheel rim and axially toward and away from the wheel rim along the wheel rim axis. According to the invention, the apparatus further comprises detecting and signaling means, arranged on the tire mounting head, for detecting an existence or non-existence of at least a prescribed minimum spacing distance between the tire mounting head and the wheel rim, and for providing to the drive arrangement a signal that is responsive to the detection and that influences the driving of the tire mounting head by the drive arrangement.

The above objects have further been achieved according to the invention in an apparatus for mounting a tire on a wheel rim of a vehicle wheel, comprising a wheel rim support, a tire bead deflector, a drive arrangement, a controller connected to the drive arrangement to control the operation thereof, a contact member configured and arranged on the tire bead deflector so as to come into contact with the wheel rim flange in the event of an improper working position of the tire bead deflector relative to the wheel rim, and a signaling arrangement. In the improper working position, the tire bead deflector fails to maintain at least a prescribed minimum spacing distance between the tire bead deflector and the wheel rim. The signaling arrangement is connected to and actuated by the contact member, and is connected for signal transmission to the controller. The signaling arrangement provides to the controller a signal in response to the contact member coming into contact with the wheel rim, and the controller controls the drive arrangement in response to the signal.

Still further, the above objects have also been achieved according to the invention in a method of mounting a tire on a vehicle wheel rim, comprising steps of supporting and securely holding the wheel rim, positioning the tire partly on the wheel rim, moving a tire mounting head including a tire bead deflector axially toward the wheel rim, rotating the tire mounting head to rotate the tire bead deflector around a wheel rim flange of the wheel rim so that the tire bead deflector deflects a tire bead of the tire around the wheel rim flange, and pressing the tire bead into a rim well of the wheel rim. During the steps of moving and rotating the tire mounting head, the method further involves monitoring whether an actual spacing distance between the tire mounting head and the wheel rim is at least equal to a prescribed minimum spacing distance. If the actual spacing distance falls below the prescribed minimum spacing distance, then a signal is produced. In response to the signal, the moving and/or the rotating of the tire mounting head is influenced (for example stopped).

Advantageously, the invention provides that an improper working position between the tire mounting head and the wheel rim possibly arising before or even during the tire mounting process is detected and produces a signal that suitably influences the tire mounting process. For example, the tire mounting process is not started, or the already-started tire mounting process is interrupted and the apparatus is stopped, or the tire mounting head is repositioned relative to the wheel rim. The improper working position of the mounting head, and especially the bead deflector thereof, relative to the wheel rim can arise from any of the above mentioned errors, such as errors in the wheel rim type recognition or in the transmission of the type identifying data, or errors in the adjustment of the bead deflector or the press-in roller, or errors in the support and clamping of the wheel rim. The invention provides simple means to ensure that such in improper working position does not lead to damage of the wheel rim or the tire, for example because the further operation of the tire mounting apparatus is immediately stopped if any such improper working position is detected. Then, an operator of the apparatus can determine the cause of the problem, and carry out any suitable readjustment or repositioning (for example repositioning and reclamping the wheel rim, or readjusting the position of the bead deflector or the press-in roller especially regarding the axial positions thereof). Thereafter the tire mounting process can be started or continued, without having caused any damage to the tire or the rim. Thereby the reject rate can be significantly reduced.

It is also advantageous that the invention does not require complex or costly additional devices, because the position or spacing detection arrangement is preferably incorporated into the existing bead deflector in a simple manner. An especially advantageous further embodiment provides a wireless signal transmission from the position detection arrangement of the bead deflector to the drive arrangement or the controller thereof. Thereby a hard-wired cable connection can be omitted, although an alternative embodiment uses a hard-wired transmission of an electrical signal through an electrical cable connection or of an optical signal through an optical fiber connection. Such cable connections can be problematic and subject to interference or breakdown in the actual production process, especially if the cables must undergo rapid movements in operation, in this case the axial and circular or rotational movements of the tire mounting head. The preferred wireless transmission according to the invention preferably is carried out as a radio transmission (e.g. radio frequency RF transmission), but alternatively may be carried out as an optical transmission (e.g. an infrared IR transmission).

In a structurally simple preferred embodiment of the invention, a suitable position detection element is incorporated into or arranged on an end surface of the bead deflector that faces toward or cooperates with the wheel rim flange. In a particularly simple and robust embodiment, the position detection element is a contact member or especially a switching feeler shoe of a switching arrangement. When the switching shoe contacts the wheel rim flange, the switching shoe is displaced through a switching displacement, and in turn displaces a switching pushrod connected thereto, so that the pushrod is slidingly displaced against a return spring force, and in turn activates a switch that is preferably embodied as a piezoelectric switch. This piezoelectric switch includes a switching mechanism as well as a piezoelectric crystal element that serves as an energy source. Since the piezoelectric effect is used for supplying the necessary energy for the position detection signal, it is not necessary to provide any external energy source or any other internal energy source such as a primary or secondary battery in the bead deflector. The piezoelectrically generated energy can also be used for carrying out the wireless transmission of the resulting signal, i.e. for powering the signal transmitter.

A gentle handling or treatment of the tire is ensured by a further embodiment in which the working end surface of the bead deflector comprises a first surface section that extends perpendicularly to the axis of the bead deflector, and a second surface section that protrudes away obliquely at a slope or tilt angle from the first surface section. Preferably, the second surface section is oriented to slope obliquely away from the first surface section at an angle of 45°.

The switching shoe of the position detection arrangement preferably has a similar configuration as the working end surface of the bead deflector, with two portions thereof respectively partially recessed into a groove along the first surface section and the second surface section of the working end surface of the bead deflector. With such an embodiment, the wheel rim flange will contact the obliquely sloping surface of the switching shoe for either (or both) a radial improper working position and/or an axial improper working position of the bead deflector relative to the wheel rim. In other words, if the bead deflector is improperly radially positioned, or improperly axially positioned, relative to the wheel rim flange, then the rim flange will contact the sloping surface of the switching shoe so as to cause an axial displacement of the switching push rod in the axial direction and thereby cause an operation of the switching arrangement, to generate a signal indicative of the existence of the improper position in which the prescribed minimum spacing distance is not being maintained. That signal is transmitted to the controller and/or drive of the tire mounting head, so as to stop or interrupt the motion of the mounting head, or even to readjust the position of the mounting head in an automatic responsive manner.

DETAILED DESCRIPTION OF A PREFERRED EXAMPLE EMBODIMENT AND OF THE BEST MODE OF THE INVENTION

FIG. 1schematically illustrates an apparatus for mounting a tire1onto a wheel rim2of a vehicle wheel. The tire mounting apparatus is arranged and supported in a machine frame or tire mounting station, of which the further components are not shown. The wheel rim2is supported on a wheel support platform9, which is schematically indicated, and which includes any conventionally known wheel holding or clamping device. The wheel rim2is thus fixedly secured and held in the horizontal position on the wheel support platform9by the wheel rim clamping device (not shown in detail) thereof.

Above the wheel rim2, the tire mounting or draw-down head3of the tire mounting apparatus is movably arranged on the machine frame so that the rotation axis of the tire mounting head3coincides with the vertical wheel rim axis of the wheel rim2. More particularly, the mounting head3is connected to and supported by a drive arrangement13so as to be rotatable by at least one rotation about the vertical axis and to be displaceable in a stepless stroke manner in the axial direction, as respectively indicated by the two motion arrows. Thus, the drive arrangement13includes a rotational drive mechanism and a linear stroke drive mechanism, which may, for example, be operated electrically (e.g. an electric motor) and/or via a suitable pressure medium (e.g. a hydraulic motor or piston-cylinder device). Also, the drive arrangement13is connected to or integrated with a control arrangement7, which controls the operation of the drive arrangement13.

To carry out a tire mounting process, i.e. to press a respective tire1onto a respective matching wheel rim2, the drive13drives the mounting head3vertically into a (nominally proper) axially spaced position relative to the wheel rim2, and then drives the mounting head3rotationally to carry out at least one full rotation, to mount the tire as will be explained below. In this regard, the mounting head3must be properly positioned and especially axially adjusted by the drive arrangement13under the control of the control arrangement7, dependent on the axial position of the wheel rim side face of the respective wheel rim2positioned in the mounting station. Thus, if successive wheel rims have different sizes, profiles, or types, then the mounting head3will have to be appropriately positioned to different axial positions respectively proper for the respective different wheel rims. For this purpose, the control arrangement7can receive signals from a preceding type-recognition arrangement for recognizing and identifying the different types or sizes of wheel rims and/or tires. The control arrangement7can also receive manual information through any suitable operator input arrangement, such as a keyboard or adjustment switches, to identify the wheel rim and tire type to be processed at any given time. The control arrangement7then properly controls the drive arrangement13so as to position the working components of the mounting head3properly relative to the wheel rim2and the tire1.

The working tools of the tire mounting head3include a tire bead deflector or bead folder4and a tire press-in or press-down roller5. The mounting head3may comprise a plurality of press-in rollers. The bead deflector4and the press-in roller are secured to an adapter part8of the mounting head3in such a manner so that their respective positions in the radial direction are adjustable for the purpose of accommodating or adapting to various different wheel rim and tire diameters.

The press-in roller5is rotatably supported by a support arm5a, which in turn is releasably or removably secured to the adapter part8. The rotation axis of the press-in roller5extends essentially perpendicularly to the wheel rim axis (and correspondingly the rotation axis of the mounting head3). Thus, as the mounting head3rotates around the wheel rim axis, the press-in roller5rolls along the sidewall of the tire1, whereby the roller5presses the sidewall of the tire1down below the wheel rim flange2aas will be discussed further below. In this regard, the press-in roller5is arranged behind or after the tire bead deflector4in the rotation direction of the mounting head3.

The tire bead deflector4is configured essentially cylindrically, i.e. as a cylindrical rod, and comprises a working section4athat is to be pressed against the tire bead6, a securing section4bthat secures the bead deflector4to the adapter part8, and a middle section4cextending between the working section4aand the securing section4b. The working section4acomprises an end surface10that includes a first surface section10aextending along a plane normal or perpendicular to the axis of the bead deflector4, and a second surface section10bextending obliquely or sloping relative to the first surface section10a, and especially extending at a slope angle of about 45° (e.g. 40° to 50°) relative to the axis, and sloping outwardly away from the first surface section10a. This configuration can especially be seen in the side view ofFIG. 2(further in connection with the front view ofFIG. 3).

A groove11extends linearly crosswise or transversely through the middle of the end surface10. In this regard, the groove11extends from the circumference of the working section4aof the bead deflector4in the area of the first surface section10ato shortly before (i.e. displaced inwardly from) the circumference of the working section4ain the area of the second surface section10b. In other words, while the groove has an open end at the circumference of the working section4aon the first surface section10a, it does not penetrate through the circumference and thus has a closed end at the circumference of the second surface section10b. This side of the circumferential surface12of the bead deflector4(adjacent to the second surface section10b) is allocated to, faces toward and presses against the tire bead6, while the end surface10including the surface sections10aand10bis allocated to and faces toward the wheel rim flange2a(seeFIG. 4).

The tire bead deflector4further comprises a signaling device or arrangement20, which generates or releases a signal that is indicative of a relative position (or spacing) of the bead deflector4with respect to the wheel rim flange2a, and that is provided to the control arrangement7and/or the drive arrangement13to influence the motion of the tire mounting head3. The signaling device20comprises a switching arrangement21, an energy source22, and a signal transmitter23, which is preferably a wireless (e.g. RF or IR) transmitter, but may alternatively be a hardwired transmitter. The signal transmitter23(preferably wirelessly) transmits the signal to the drive arrangement13and/or the control arrangement7for influencing, especially for stopping, the drive arrangement. The significance of this will be discussed further below. In this regard, the transmitter23is connected for signal transmission to the drive arrangement23and/or the control arrangement7, e.g. by an RF wireless transmission link, an IR wireless transmission link, a wire, an optical fiber, or other signal transmission link.

The switching arrangement21comprises a switching feeler shoe or foot21a, a switching pushrod21bconnected to and actuated by the switching shoe21a, and a switch mechanism21cthat is acted on and actuated by the switching pushrod21b. The switching shoe21aconsists of a material with a significantly lower hardness than the material of the wheel rim2, and with good sliding or anti-friction characteristics. The terms anti-friction and low-friction mean exhibiting a lower coefficient of friction than steel sliding against steel. For example, the switching shoe21amay be made of any one of various low-friction plastic materials such as polytetrafluoroethylene (PTFE). Thus, if the switching shoe21acomes into contact with the wheel rim2and particularly the wheel rim flange2a, then the switching shoe21acan easily slide along the rim flange2awithout causing any damage thereto. The switching shoe21athereby forms a device or arrangement for detecting the existence or non-existence of a minimum spacing distance between the wheel rim2and the tire mounting head3, particularly the bead deflector4of the mounting head3, whereby the prescribed minimum spacing distance is given by the protrusion distance of the switching shoe21abeyond the end surface10of the bead deflector4.

The switching shoe21ais configured and dimensioned so as to fit into the groove11provided in the end surface10of the bead deflector4. In this regard, a biasing spring, such as a compression spring21d, acting on the switching pushrod21bbiases the switching shoe21ato protrude outwardly from the groove11, but the switching shoe21acan be pressed against the spring force to be partly received or recessed in the groove11. The switching shoe21ahas a contour shape that is matched to the shape of the end surface10, i.e. including an angled profile having two shoe portions extending at an oblique angle relative to one another respectively along the first surface section10aand the second surface section10b.

During the axial and/or radial positioning and motion of the mounting head3and especially the bead deflector4relative to the wheel rim2, if the minimum spacing distance between the mounting head3(especially the bead deflector4thereof) and the wheel rim2is no longer maintained, then the wheel rim flange2awill contact a sloping surface of the switching shoe21aas shown inFIG. 4. Such contact of the wheel rim flange2awith the sloping surface of the switching shoe21awill arise for both improper radial positions (as indicated by the arrow R inFIG. 4) as well as improper axial positions (as indicated by the arrow A inFIG. 4) of the wheel rim flange2arelative to the bead deflector4(or vice versa). In any event, either an improper radial positioning R or an improper axial positioning A of the rim flange2acontacting the switching shoe21awill result in an axial displacement of the switching shoe21ato be recessed into the groove11, which in turn causes an axial pushing displacement of the switching pushrod21bagainst the spring force of the biasing spring21dupwardly as indicated by the upward axial direction arrow at the top ofFIG. 4. Thus, through the arrangement of two end surface sections10aand10bthat are tilted relative to one another, the first surface section10a(and its associated portion of the switching shoe) can detect a height impact or deviation of the wheel rim2, while the second surface section10b(and its associated portion of the switching shoe) can detect an axial or radial impact or deviation of the wheel rim2, respectively onto the associated portions of the switching shoe21a.

As can be further understood in connection withFIG. 2, the upward sliding displacement of the switching pushrod21bdue to the upward recessing motion of the switching shoe21aconnected thereto is transmitted by the switching pushrod21baxially through the bead deflector4and acts as a sliding displacement or stroke motion onto the switch mechanism21c. The switching motion of the switch mechanism21cin turn acts on a piezoelectric element provided as the energy source21. In response to this mechanical switching actuation, the piezoelectric element or energy source22generates an electric signal, e.g. an electrical pulse, which is then transmitted by the transmitter23to the control arrangement7and/or the drive arrangement13. In this regard, the electrical energy emitted by the actuated piezoelectric element22can also be used to power the transmitter23, which is preferably a wireless transmitter23.

In the illustrated preferred example embodiment, the switch mechanism21c, the piezoelectric element or energy source22, and the transmitter23are all arranged in common in a housing at the opposite or upper end surface of the bead deflector4, i.e. at the upper end surface of the securing section4bopposite from the working section4a. Alternatively, however, the signaling device or arrangement20can be arranged at any other suitable or desired location of the mounting head3. Also, as a further alternative, a force-dependent signaling arrangement can be provided instead of a displacement-dependent switching arrangement21. As a further alternative, the signaling arrangement can be based on, and can release or trigger the transmission of a corresponding signal as a result of an electrical contact measurement of an electrical contact member or feeler contacting the wheel rim flange.

The process of mounting a tire1onto the wheel rim2of a vehicle wheel using the inventive tire mounting apparatus will now be described. First, the tire1is arranged over the wheel rim2in a sloping or tilted manner so that the tire bead6is partly located within the deep recessed well of the wheel rim2and partly protrudes above the upper wheel rim flange2a. To carry out the tire mounting process, the wheel rim2is securely held or clamped onto the wheel support platform9. The tire mounting apparatus has previously obtained appropriate data identifying the wheel rim dimensions and possibly also the tire dimensions of the tire and rim combination that is to be assembled or mounted. These data may be provided, for example, from a preceding automatic type-recognition arrangement, or from a manual input by an operator of the apparatus. In response to these data, the control arrangement7controls the drive arrangement13and any further actuators as necessary to adjust the components of the mounting head3to the proper tire and wheel dimensions, and then to lower the mounting head3axially by a prescribed displacement distance toward the wheel rim2.

The tire mounting or assembling process begins in the area of the tire1in which the tire bead6lies approximately at the height of the wheel rim flange2a. At the beginning of the mounting process, the end surface10of the bead deflector4of the mounting head3is positioned at a certain prescribed minimum spacing distance away from (e.g. above) the associated wheel rim flange2a. Moreover, the bead deflector4is positioned so that the axially further protruding portion of the outer circumferential surface12thereof (adjacent to the second surface section10b) presses against the tire bead6and thereby pushes the tire bead6radially outwardly beyond and around the edge of the rim flange2a. As the mounting head3is rotated, the bead deflector4rotates around and along the edge of the wheel rim flange2aand thereby guides the tire bead6radially outwardly along a circle around and over the edge of the wheel rim flange2a, as the following press-in roller5then presses the tire bead6downwardly into the deep recessed well of the wheel rim2. The tire mounting or assembling process is completed and ends when the mounting head3has carried out a 360° rotation.

If the actual spacing distance between the end surface sections10aor10bof the bead deflector4and the neighboring surface areas of the wheel rim flange2afalls below the prescribed minimum spacing distance, during the initial lowering of the mounting head3, i.e. especially the bead deflector4, toward the wheel rim2, or during the rotation of the mounting head3around the wheel rim axis, then the edge of the wheel rim flange2awill come into contact with the switching shoe21a, e.g. the obliquely sloping angular surface thereof, before or without coming into contact with the end surface10of the bead deflector4itself.

As soon as such a contact between the wheel rim flange2aand the switching shoe21aarises, the switching pushrod21bis thereby pushed upwardly, whereby the signaling device20is activated and releases or generates a signal indicative of the detected improper working position of the bead deflector4relative to the wheel rim2. This signal is transmitted to the control arrangement7and/or the drive arrangement13, whereupon the lowering or the rotation of the mounting head3is stopped or interrupted.

The worker who is operating or monitoring the tire mounting apparatus can then determine and correct the cause of the improper working position (e.g. by readjusting components as needed, or by resetting the proper tire and wheel size data) before any damage has been caused to the wheel rim and/or the tire. For example, if the improper working position detection signal causes a stop of the initial lowering motion of the mounting head, this can be indicative of an error in the adjustment of the mounting head components or in the detection of the wheel rim dimensions. On the other hand, a signal-triggered stopping of the rotation process of the mounting head can be caused by a faulty uncentered clamping of the wheel rim2on the wheel support platform9. As a further alternative, the generated improper working position detection signal can be used to automatically actuate a suitable corrective readjustment of the mounting head or its individual components relative to the wheel rim.