GB2460115A

GB2460115A - Tyre probe arrangement

Info

Publication number: GB2460115A
Application number: GB0809157A
Authority: GB
Inventors: George Yeomans
Original assignee: PNEU LOGIC CORP Ltd
Current assignee: PNEU LOGIC CORP Ltd
Priority date: 2008-05-20
Filing date: 2008-05-20
Publication date: 2009-11-25
Anticipated expiration: 2028-05-20
Also published as: GB0809157D0; GB2460115B

Abstract

A probe arrangement (18) for tyre measurement apparatus (10) includes a probe assembly (20). The probe assembly (20) includes a probe member (22) and an actuator (29) for moving the probe member (22) between a retracted position and an extended position. The actuator includes an electric motor 48 which drives a reel (42, fig2) via gear 54 and band 56. A cord 44 is driven by the motor to extend and retract the probe 22. A probe movement sensor 50 comprises a light source and light detector positioned either side of a perforated disc 52.

Description

A Probe Arrangement The present invention relates to a probe arrangement, particularly but not exclusively a probe arrangement for tyre measurement apparatus.

Conventionally, tyre measurement apparatus such as tread depth gauges comprise a probe member which can be extended and retracted. The probe member is typically spring loaded, so that a user presses the probe member into a tread channel against the spring, the movement of the probe member being measured by a sensor such as a linear potentiometer to provide an output indicating the tread depth. While such arrangements are satisfactory for the tyres of vehicles such as cars and lorries, very large tyres such as those for large dumper trucks have relatively deep tread channels requiring relatively large probe member movements for measurement.

Conventional arrangements of tread depth gauges for such large tyres are relatively large and cumbersome.

According to a first aspect of the present invention, there is provided a probe arrangement for tyre measurement apparatus, the arrangement including a probe assembly, the probe assembly including a probe member, zc the probe arrangement including an actuator for moving the probe member between a retracted position and an extended position.

Possibly, the actuator is arranged to move the probe member from the retracted position to the extended position and from the extended position to the retracted position.

*.. : Possibly the actuator includes a motor, which may be an electric motor.

*:* Possibly, the actuator includes a reel, a pulley, and a flexible elongate member which is associated with the probe member, the flexible elongate

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member extending around the reel and pulley. Possibly, the motor drives the * .* * S * * *S reel, moving the flexible elongate member, which in turn moves the probe member.

Possibly, the probe arrangement includes a movement sensor, for sensing the amount of movement of the probe member. The movement sensor may include a light source, a light sensor and a light chopper. The light chopper may be located between the light sensor and the light source, and may be in the form of a perforated disc. The light chopper may be mounted in association with the reel, so that rotation of the reel rotates the light chopper.

Possibly, the probe arrangement includes a limit sensor to limit movement of the probe member.

Possibly, the probe arrangement includes a support for supporting the probe member. The support may include a guide for guiding the movement of the probe member.

According to a second aspect of the present invention, there is provided tyre measurement apparatus, the apparatus including a probe arrangement as defined in any of the preceding statements.

An embodiment of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:-Fig. 1 is a schematic perspective cross sectional view of tyre measurement apparatus; *s.. * * * ** S

*::* Fig. 2 is a perspective view of a probe arrangement; ** .* * * * * Fig. 3 is an enlarged detail of part of the probe arrangement of Fig. 2; and * ** * S * * *S Fig. 4 is another enlarged detail of another part of the probe arrangement of Fig. 2.

Referring to Figs. 1 to 4, tyre measurement apparatus 10 includes a body 12, a handle 14 extending from the body 12 at one end, and a datum part 16 located at an opposite end of the body 12. The body 12, the handle 14 and the datum part 16 together form a hollow casing 13, which could be formed of plastics material.

The tyre measurement apparatus 10 includes a probe arrangement 18, which is located within the hollow casing 13. The probe arrangement 18 includes a probe assembly 20 comprising a probe member 22. The probe assembly 20 includes a probe member support 24.

The probe arrangement 18 includes a support 30 which includes a first support member 32, a second support member 34 spaced from the first support member 32, and a guide including a pair of guide members 36 extending between the first and second support members 32, 34. The probe member support 24 extends between the guide members 36. The probe member 22 extends from the probe member support 24 through a hole 26 defined in the first support member 32. The hole 26 is lined by a bush 28 of relatively low friction material.

The probe arrangement 18 includes an actuator 29 including a reel 42 located within a cavity 38 defined by the second support member 34 and mounted to an axle 46, a pulley 40 located within a cavity 39 defined by the *:*. first support member 32 and a flexible elongate member in the form of a cord 44 which extends from the probe member support 24, around the reel 42 and the pulley 40 and back to the probe member support 24. The cord 44 could **** be formed of a relatively non stretching material, and could be formed of a material which is relatively resistant to changes in properties due to differing * .* * ** environmental conditions such as temperature or humidity. The actuator 29 could include tensioning means for tensioning the cord 44. For example, the cord 44 could include a spring, or could include a part formed of an elastic material.

The cord 44 is wound several times around the reel 42 to reduce the risk of slippage of the cord 44 relative to the reel 42. In one example the cord 44 is wound around the reel 42 five times.

The actuator 29 includes an electric motor 48 which drives the reel 44 via gear wheels 54 and a band 56, one of the gear wheels 54 being mounted to the axle 46. The band 56 could be formed of a material having a resilient property, such as rubber, and the gear wheels 54 could be arranged so that the band 56 is in tension.

The probe arrangement 18 includes a movement sensor 50 which includes a sensor body 58, the sensor body 58 including a light source and a light detector which are positioned on either side of a light chopper in the form of a perforated disc 52, the perforated disc 52 including a plurality of regularly spaced perforations. The perforated disc 52 is mounted to the axle 46, so that as the motor 48 drives the reel 42 and the reel 42 rotates, the perforated disc 52 also rotates.

The tyre measurement apparatus 10 includes a controller 66, which is in signal communication with the motor 48 and the movement sensor 50.

The tyre measurement apparatus 10 could include a circuit board 60 and batteries 62 located within the handle 14, and could include other components as required or desired, such as air pressure sensing means and/or temperature sensing means. The tyre measurement apparatus 10 could include an RFID antenna 64, which could be located in the datum part 16. * ** * . S * .*

In use, the probe member 22 is initially moved to a fully retracted position. To establish a zero datum, the tyre measurement apparatus 10 is positioned so that the datum part 16 is located against a flat surface, and the apparatus 10 operated to zero the position of the probe member 22. The tyre measurement apparatus 10 is then positioned over a tread channel 72 of a tyre 70 as shown in Fig. 1, so that the datum part 16 spans across the tread channel 72: The tyre measurement apparatus 10 is operated, the motor 48 turning the axle 46 via the gear wheels 54, rotating the reel 42, which in turn moves the probe member support 24 and probe member 22 along the guide members 36, moving the probe member 22 from a retracted position to an extended position. The guide members 36 and the hole 26 guide the movement of the probe assembly 20. As the axle 46 rotates, the perforated disc 52 provides regular flashes of light to the light sensor within the sensor body 58 which are counted by the light sensor, providing an indication of the distance moved by the probe member 22. In one example, each light flash indicates a distance moved by the probe member 22 of 0.1mm.

When the probe member 22 contacts the bottom of the tread channel 72, the movement of the probe member 22 stops, stopping the rotation of the perforated disc 52 which is sensed by the sensor which is in signal communication with the controller 66, which then causes the motor 48 to reverse direction, so that the probe member 22 now begins to move back from the extended position to the retracted position. The sensor thus provides a limit sensor to limit movement of the probe member 22. Thus, as soon as the movement of the probe member 22 is stopped by the bottom of the tread channel 72, the motor 48 is reversed, preventing any problems due to the motor 48 continuing to run after contact between the probe member 22 and 0* * the bottom of the tread channel 72. * ..* **S

In an alternative embodiment, the probe arrangement 18 could include a limit sensor in the form of an over current sensor, and the motor 48 could * ** * * * S. continue to run after contact between the probe member 22 and the bottom of the tread channel 72. As the current taken by the motor 48 rises due to the increased frictional force provided by the stalled probe assembly 20, the over current sensor provides a signal to the controller 66 which causes the motor 48 to operate in reverse, moving the probe member 22 from the extended position to the retracted position. The over current sensor could be adjusted to vary the contact pressure of the probe member 22 on the bottom of the tread channel 72.

There is thus provided a probe arrangement 18 for a tyre measurement apparatus 10 which allows the measurement of relatively deep tread channels of very large tyres. For example, very large tyres of dumper trunks can have tread channels of depth in the range 50 -200mm. The probe arrangement 18 of the present invention is relatively compact and robust, permitting the tyre measurement apparatus 10 to be relatively compact and easy to handle, while being accurate. The arrangement 18 provides the advantage that the probe member 22 is positively driven both in moving from the retracted to the extended position and vice versa. The arrangement 18 provides sensing of contact between the probe member 22 and the bottom of the tread channel 72, reducing the risk of damage to components. The arrangement 18 can be incorporated into tyre measurement apparatus 10 including a variety of other sensors, such as pressure sensors, temperature sensors, etc. Various other modifications could be made without departing from the scope of the invention. The motor could be of any suitable type. The cord could be of any suitable type. The first and second support members and the guide members could be of any suitable material, and could be of any suitable size and shape.

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Whilst endeavouring in the foregoing specification to draw attention to *.

those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any * ** * 5 0 * 0S patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon. S.. * . .

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Claims

Claims 1. A probe arrangement for tyre measurement apparatus, the arrangement including a probe assembly, the probe assembly including a probe member, the probe arrangement including an actuator for moving the probe member between a retracted position and an extended position.
2. An arrangement according to claim 1, in which the actuator is arranged to move the probe member from the retracted position to the extended position and from the extend position to the retracted position.
3. An arrangement according to claims 1 or 2, in which the actuator includes a motor.
4. An arrangement according to claim 3, in which the motor is an electric motor.
5. An arrangement according to any of the preceding claims, in which the actuator includes a reel, a pulley, and a flexible elongate member which is associated with the probe member, the flexible elongate member extending around the reel and pulley.
6. An arrangement according to claim 5 when dependent upon claims 3 or 4, in which the motor drives the reel, moving the flexible elongate member, which in turn moves the probe member.
7. An arrangement according to any of the preceding claims, in which the probe arrangement includes a movement sensor, for sensing the amount of *** movement of the probe member. * ** * * *** *
8. An arrangement according to claim 7, in which the movement sensor * includes a light source, a light sensor and a light chopper. *ISS S. * * *.
9. An arrangement according to claim 8, in which the light chopper is located between the light sensor and the light source.
10. An arrangement according to claims 8 or 9, in which the light chopper is in the form of a perforated disc.
11. An arrangement according to any of claims 8 to 10 when dependent upon claim 5 or any claim dependent thereon, in which the light chopper is mounted in association with the reel, so that rotation of the reel rotates the light chopper.
12. An arrangement according to any of the preceding claims, in which the probe arrangement includes a limit sensor to limit movement of the probe member.
13. An arrangement according to any of the preceding claims, in which the probe arrangement includes a support for supporting the probe member.
14. An arrangement according to claim 13, in which the support includes a guide for guiding the movement of the probe member.
15. Tyre measurement apparatus, the apparatus including a probe arrangement as defined in any of the preceding claims.
16. A probe arrangement substantially as hereinbefore described and with *:::. reference to any of the accompanying drawings. *s**
17. Tyre measurement apparatus substantially as hereinbefore described .:3O and with reference to any of the accompanying drawings.S *.SSSSS
18. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims. *** * I * *. I * .II S * *I. * * I IIII I *IIII*,*Il* * I ** * I * * * *