Dynamic imbalance determining apparatus

Abstract: A rotary element dynamic imbalance determining apparatus (20) includes a spindle (22) having a first end for removably supporting a rotary element (26) the imbalance of which is to be determined, and a housing (28) for rotatably mounting the spindle (22). An output signal related to imbalance in the supported rotary element (26) is generated as the spindle (22) rotates. A rotary fluid coupling (52) comprises a chamber (60) between the spindle (22) and housing (56), a port (62) in the housing (56) for coupling the chamber (60) to a source of compressed air and a one-way fluid seal (66) for dividing the chamber into a first portion (68) and a second portion (70). A passageway (72, 84) extends along the spindle (22) from the first and second portion (68, 70) to the first end of the spindle.

Description: This invention relates to systems for determining dynamic imbalance in rotary elements. It is disclosed in the context of dynamic imbalance determining systems for vehicle wheel and tyre assemblies and unmounted vehicle tyres. However it is believed to be useful in other applications as well. Various kinds of automated imbalance determining apparatus are known. There are the kinds of apparatus described in, for example, U.S. Patent 4,191,055 and the references cited in that patent. EP-A-0097721 and DE-A-4037745 disclose rotary element dynamic imbalance determining apparatus in which a rotary element is supported on one end of a spindle rotatably mounted in a housing. The spindle is rotated by means comprising a motor rotor mounted on the spindle and a motor stator mounted on the housing. As the spindle rotates, the vibration of the spindle is detected to produce an output signal related to imbalance in the supported rotary element. DE-A-3400506 discloses a balancing machine wherein a vehicle wheel is supported by means of a hydraulic or pneumatic clamp. US-A-3935748 discloses a tiltable balancing machine for inflated pneumatic tires wherein means are provided to inflate and deflate a tire whilst mounted on the balancing machine. According to this invention, a rotary element dynamic imbalance determining apparatus including a spindle having a first end for removably supporting a fluid-inflatable rotary element including means defining a mounting hole, the imbalance of said rotary element being to be determined, a housing for rotatably mounting the spindle, and means for providing an output signal related to imbalance in the supported rotary element as the spindle rotates, and means for rotating the spindle, the spindle rotating means comprising a motor rotor, means for mounting the motor rotor on the spindle, a motor stator, means for mounting the motor stator on the housing, and the means for removably supporting the rotary element on the first end of the spindle comprises a fluid-operated chuck for engaging to grip the rotary element removably and disengaging to release the rotary element, wherein the spindle comprises means for selectively permitting the flow of an inflating fluid into the fluid-inflatable rotary element and out of the fluid-inflatable rotary element selectively to inflate and deflate, respectively, the fluid-inflatable rotary element and in that; a rotary fluid coupling is provided on the spindle for permitting fluid flow to and from the fluid-operated chuck and/or to and from the fluid inflatable rotary element. Preferably the rotary fluid coupling comprises a chamber defined between the spindle and the housing, means providing in the housing a first port for coupling the chamber to a source of the chuck-operating fluid, a first one-way fluid seal for dividing the chamber into a first portion and a second portion, and a first fluid passageway extending along the spindle from the first portion of the chamber to the fluid-operated chuck. Illustratively, the fluid-operated chuck comprises a pneumatic chuck. Illustratively according to an embodiment of the invention, a servo motor controller is provided along with means for selectively coupling the servo motor controller to at least one of the motor rotor and motor stator to control the motor. Additionally illustratively according to an embodiment of the invention, the means for selectively coupling the servo motor controller to at least one of the motor rotor and motor stator comprises means for effectively disabling the servo motor controller during a rotary element dynamic imbalance determining interval. Further illustratively according to an embodiment of the invention, the motor rotor and stator together comprise a brushless direct current motor. Examples of the invention will now be described with reference to the accompanying drawings, in which:- Figure 1 illustrates, in partly block and diagrammatic form, a system constructed according to the invention; Figure 2 illustrates a fragmentary side elevational view of a system constructed according to the invention; Figure 3 illustrates a primarily fragmentary sectional view, taken generally along section lines 3 - 3, of Figure 2; Figure 4 illustrates a primarily fragmentary side elevational view of another system constructed according to the invention; and, Figure 5 illustrates a fragmentary top plan view, taken generally along section lines 5 - 5, of Figure 4. Referring now to Figures 1 to 3, a rotary element dynamic imbalance determining apparatus 20 includes a spindle 22 of the general type described in U.S. Patent 4,191,055 having a first end 24 for removably supporting a rotary element 26 the imbalance of which is to be determined. Illustratively, the rotary element is a vehicle wheel-and-tyre assembly. A spindle housing 28 rotatably mounts the spindle 22 in bearings 29. Load cells 30 positioned between the spindle housing 28 and the frame 32 of apparatus 20 provide output signals related to imbalance in the supported rotary element 26 as the spindle 22 rotates. The spindle 22 is rotated by a motor 34 including a rotor 36 mounted by bolts 38 on the spindle 22, a motor stator 40, and a housing 42 for mounting the motor stator 40 to the spindle housing 28. The motor rotor 36 and stator 40 together comprise a brushless direct current motor 34. The rotary element 26 includes a centre hole 44. A pneumatically operated chuck 46 is mounted on the first end 24 of spindle 22 for engaging the centre hole 44 to grip the rotary element 26, and disengaging the centre hole 44 to release the rotary element 26. A rotary fluid coupling 50 at a second end 52 of spindle 22 permits air flow to and from the pneumatically-operated chuck 46. The rotary fluid coupling 50 comprises a somewhat cup-shaped member 56 for attachment to the housing 42 for defining between the second end 52 of the spindle 22 and the member 56 a chamber 60. A first port 62 is provided in the member 56 for coupling the chamber 60 to a source 64 of chuck-operating air. A first one way fluid seal 66 divides the chamber 60 into a first portion 68 and a second portion 70. A first fluid passageway 72 extends along the spindle 22 from the first portion 68 of the chamber 60 to the pneumatically-operated chuck 46. In another embodiment of the invention illustrated in Figures 1 and 4 to 5, the rotary element 26 is an unmounted vehicle tyre. The first end of the spindle includes unmounted tyre mounting and inflating tooling. The spindle 22 also comprises a rotary air coupling 76 for permitting compressed air flow to and from the spindle 22. The coupling 76 includes a second port 78 in the member 56 for coupling the chamber 60 to a source 80 of the compressed air and second one-way fluid seals 82 for dividing the chamber 60 into the first portion 68 and second portion 70. Second air passageways 84 extend along the spindle 22 from the second portion 70 of the chamber 60 to the first end 24 of the spindle 22 to supply rotary element-inflating compressed air thereto. A pressure transducer 86 in second portion 70 of chamber 60 feeds back inflating air pressure. A servo motor controller 90 is selectively coupled by a micro-controller 92 to the motor stator 40 to control the motor 34. The micro-controller 92 effectively disables the servo motor controller so during a rotary element dynamic imbalance determining interval to prevent servo control loop jitter from affecting the imbalance determination. The servo control loop is closed by a position encoder 96 mounted on the outside of housing 42. Position encoder 96 has an input shaft which carries a driven pulley 98. A driving pulley 100 is mounted adjacent the end 52 of spindle 22 at the junction of housing 42 and member 56. A slot-like opening 102 is provided between housing 42 and member 56 for passage of a toothed timing belt 104 which is trained about both of pulleys 98, 100 to provide the necessary rotation frequency information to encoder 96 and thus to servo motor controller 90. The same motor 34, housing 42 and member 56 are used in both of the illustrated embodiments. In the embodiment of Figures 2 to 3, the transducer 86 port is plugged 108 since the transducer 86 is not employed in that embodiment.

Claims: A rotary element dynamic imbalance determining apparatus (20) including a spindle (22) having a first end for removably supporting a fluid-inflatable rotary element (26) including means defining a mounting hole (44), the imbalance of said rotary element being to be determined, a housing (28) for rotatably mounting the spindle (22), and means (30) for providing an output signal related to imbalance in the supported rotary element (26) as the spindle rotates, and means (34) for rotating the spindle (22), the spindle rotating means (34) comprising a motor rotor (36), means for mounting the motor rotor (36) on the spindle (22), a motor stator (40), means for mounting the motor stator (40) on the housing (28), and the means for removably supporting the rotary element on the first end of the spindle comprises a fluid-operated chuck (46) for engaging to grip the rotary element (26) removably and disengaging to release the rotary element (26) characterised in that ; the spindle (22) comprises means (84) for selectively permitting the flow of an inflating fluid into the fluid-inflatable rotary element and out of the fluid-inflatable rotary element selectively to inflate and deflate, respectively, the fluid-inflatable rotary element and in that; a rotary fluid coupling (50) is provided on the spindle (22) for permitting fluid flow to and from the fluid-operated chuck (46) and/or to and from the fluid inflatable rotary element (26). An apparatus according to claim 1, wherein the means for providing a rotary fluid coupling (50) comprises means (56) defining between the spindle (22) and the housing (28) a chamber (60), means providing a first port (62, 78) for coupling the chamber (60) to a source of fluid (64, 80), a first one-way fluid seal (66) for dividing the chamber into a first portion (68) and a second portion (70), and a first fluid passageway (72) extending along the spindle (22) from the first portion (68) to the top of the spindle. An apparatus according to claim 2, wherein the means (50) for providing a rotary fluid coupling also includes means (78) providing a second port in the housing for coupling the chamber (60) to a source of fluid and a second one-way fluid seal (82) for dividing the chamber (60) into a first portion (68) and a second portion (70), and a first and second (72, 84) fluid passageway extending along the spindle (22) to the first end of the spindle (22) to supply rotary element-inflating and chuck operating fluid thereto. An apparatus according to any one of the preceding claims, further comprising a servo motor controller (90) and means (92) for selectively coupling the servo motor controller (90) to at least one of the motor rotor (36) or motor stator (40) to control the motor (34). An apparatus according to claim 4, wherein the means (92) for selectively coupling the servo motor controller (90) to at least one of the motor rotor (36) or motor stator (40) comprises means for effectively disabling the servo motor controller (90) during a rotary element (26) dynamic imbalance determining interval. An apparatus according to any one of the preceding claims, wherein the motor rotor (34) and stator (40) together comprise a brushless direct current motor (34).

Inventors: CARLSON ROY F, GROSS PETER L, CARLSON, ROY F., GROSS, PETER L.
Applicants: RANSBURG CORP, RANSBURG CORPORATION
Application year: 1995
Main classification: G01M1
IPC codes: G01M1