Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D25/00—Fluid-actuated clutches
  • F16D25/12—Details not specific to one of the before-mentioned types
  • F16D25/126—Details not specific to one of the before-mentioned types adjustment for wear or play
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D25/00—Fluid-actuated clutches
  • F16D25/12—Details not specific to one of the before-mentioned types

Definitions

• This invention relates to a device for the warning of wear in a clutch servo for a disk clutch as indicated in the preamble to claim 1 attached.
• Wear indication is in this case obtained in that when clutch linings are worn an air piston arranged in the clutch servo experiences such a return movement that it causes a valve in the servo to leak a proportion of the air out from the clutch servo. This causes the servo action- from the air to be reduced, which the driver feels as the clutch pedal becomes harder to press. Moreover, the escaping air causes an acoustic signal to be transmitted to the driver.
• the acoustic signal which is to be generated by the released air flow is also of marginal importance. In modern vehicles with effectively soundproofed cabs and enclosed engines and transmissions it is not perceptible by the driver. In buses with rear mounted engines the distance between the driver and the clutch servo is so long that no acoustic signal is audible to the driver.
• the objective of this invention is to provide an arrangement for indicating the wear of the clutch disks which does not suffer from the problems of the solution of prior art discussed, above.
• the objective of the invention is therefore to provide an indication that the disks have worn to such an ' extent that they require replacing as soon as possible.
• the indication should be given primarily in that the driver finds it much harder to press the clutch pedal than normally.
• the objectives sought are achieved in that the device is designed as indicated in the characterising part of claim 1.
• a further advantage of the invention is that although the clutch pedal feels harder to press down when the linings are worn, the clutch can still be operated and the vehicle can continue to be driven normally in all other respects.
• the invention enables the clutch servo, in normal operation, to be optimised and dimensioned with a large supply of compressed air during clutch operation, before the linings have worn to such an extent that they require replacing. This provides a fast, easily operated clutch.
• Fig. 1 shows diagrammatically a device according to the invention for operating a clutch
• Fig. 2 shows a sensor incorporated in the device.
• a clutch pedal 1 is arranged near the driver's seat in the vehicle for operating a clutch of the disk type arranged in the transmission of the vehicle between a driving engine and a gearbox.
• Clutch pedal 1 is mounted in bearings in a cowl panel 2, to which is also secured a main cylinder 3.
• the clutch of the vehicle is reproduced diagrammatically in the figure in the form of a lever 4 designed to operate the clutch in the conventional manner.
• Lever 4 is mechanically connected by a piston rod 5 to an air piston* 12 accommodated in a housing, which piston is incorporated in a clutch servo 6 for operating the clutch.
• Clutch servo 6 is connected to clutch pedal 1 by means of a hydraulic pipe 7 between coupling servo 6 and main cylinder 3 actuated by pedal 1, for transferring the pedal movement to clutch servo 6.
• Clutch servo 6 incorporates a housing 8 with an inlet connection 9 for compressed air, which connection is connected by a compressed air pipe 10 to a compressed air source.
• the compressed air source consists of the braking system of the vehicle, more precisely one of the compressed air tanks 11 of the braking system.
• the connection is suitably made via a pressure reducing valve
• piston rod 5 is rigidly connected to air piston 12, and is also connected to a hydraulic piston, not shown.
• a servo valve (not shown) , which controls the air fed to housing 8, according to the pedal movement and the hydraulic pressure from main cylinder 3, is also arranged in housing 8, so that air piston 12 in the housing is actuated and the intended servo effect is provided when the clutch is operated.
• the servo valve is arranged to open the air supply at such an early stage that essentially the entire disengaging work is carried out by air piston 12.
• the hydraulic piston is intended mainly to perform a parallel safety function enabling the clutch to be operated in the event of failure of the compressed air supply, or if it is considerably reduced.
• the clutch is therefore operated fully or partially by the hydraulic piston mainly when the auxiliary force which the clutch servo is designed to provide fails, causing the clutch pedal to be harder to press. Because clutch servos of this type are well known in themselves, and a more detailed knowledge of them is not required for an understanding of this invention, no further description of them will be given here.
• Clutch servo 6 comprises an indicating device according to the invention to indicate to and warn the driver that the clutch linings are worn and require to be replaced with new ones.
• the indicating device comprises a valve 16 which can be actuated by air piston 12 and which is shown in Figure 1 as a separately arranged valve, but which is in practice suitably incorporated in housing 8.
• Valve 16 is a so- called 3/2 valve, which means that it has three connections and two positions.
• Valve 16 has a first connection 17 connected to compressed air source 11, a second connection 18 connected to a compressed air pipe 21 provided with a fixed throttle 20, and a third connection 19 connected to an unthrottled, normal compressed air pipe 22.
• Both compressed air pipes 21, 22 are connected to each other in a branch connection 23, in which both pipes 21, 22 pass into a common compressed air pipe 24 connected to the compressed air inlet 9 of the housing.
• first connection 17 is connected by valve 16 to third connection 19, enabling compressed air to be fed without obstruction to inlet 9 of the housing.
• first connection 17 is instead connected to second connection 18, which means that compressed air fed to inlet 9 of housing 8 must pass through pipe 21 provided with throttle 20.
• the indicating device also includes a sensor which can be actuated by air piston 12 of clutch servo 6, and which in this example is designed as a valve piston 28, arranged so that it moves in parallel with air piston 12, as shown in Figure 2.
• a recess 29, acting as a cylinder, is arranged in housing 8 and accommodates valve piston 28, interacting with the same.
• Valve piston 28 extends with one end (in Figure 2 its right end) in working space 30 of air piston 12 i housing 8. At this end valve piston 28 is designed with an axial duct 31, which is terminated with a transverse hole 32.
• a seal 33 in the form of an O-ring, is arranged to the left of this hole 32.
• valve body 28 in this case the left end, is supported so that it is able to move axially in a hole 34 arranged in a sleeve 35 securely threaded in housing 8 and recess 29.
• valve body 28 is designed with an annular shoulder 36 which is sealed around its periphery against the wall of recess 29 by means of a seal 37 in the form of an O-ring.
• Recess 29 in housing 8 consists of two parts, both of which are cylindrical in shape and which are interconnected by means of an annular shoulder 38. As shown in Figure 2, the left section of recess 29 has a larger diameter than its right section. The right end of valve body 28 is housed in the right section of recess 29, and annular shoulder 36 of valve body 28 is housed in its left section. Both seals 33, 37 of valve body 28 bound a sealed space 41 between valve body 28 and recess 29, which space is connected, by a duct 42 in housing 8, and also by a compressed air pipe 43, to a regulating device 44 for valve 16 arranged on feed line 10. When space 41 is pressurised valve 16 will be caused to assume its activated position 26, whilst valve 16 will assume its position of rest 25 when there is no pressurisation.
• air piston 12 of clutch servo 6 will be used by a known method for providing the driver with auxiliary force in operating the clutch. After the clutch is operated air piston 12 returns by means of a return spring, in this case to the left, to a position of rest in which air piston 12 does not come into contact with the end of valve piston 28 projecting into working space 30 of air piston 12. In this case valve piston 28 will remain in its position of rest, corresponding to the position shown in Figure 2.
• valve 16 on inlet pipe 10 of clutch servo 6 assumes its position of rest 25, enabling compressed air from compressed air source 11 to pass essentially unhindered to inlet connection 9 of the clutch servo during clutch operation.
• valve body 28 in recess 29 to be displaced to the left, in Figure 2, and the right seal 33 of valve body 28 to pass shoulder 33 in space 29, thereby connecting sealed space 41, by means of axial duct 31 and transverse hole 32, to working space 30 of clutch servo 6.
• valve piston 28 As seal 33 of the valve piston passed shoulder 38 of recess 29 the space between seals 33, 37 was pressurised. This caused annular shoulder 36 of valve piston 28 to be exposed to the working pressure of the clutch servo on its right side, which caused valve piston 28 to be displaced to a limit position at which contact with air piston 28 ceased.
• This limit position corresponds to the position assumed by valve piston 28 when its shoulder 36 comes into contact with the end of sleeve 35 threaded into the left end 29 of the space.
• the displacement of valve piston 28 to the left causes its left end to project from hole 34 of sleeve 35, which is a further indication that the linings are worn and that the indicating device has triggered as it is designed to.
• a pressure medium may also be considered to include negative pressure media, i.e. mainly vacuum, as far as air is concerned.
• a pipe can be used in which a variable throttle is directly connectable. This may be suitably designed as a two-position valve, one of whose positions corresponds to an unthrottled feed, and whose other position gives rise to throttling.
• valve piston 28 is a sensing mechanism which is used to actuate a separate valve 16.
• the sensing mechanism and the valve can be integrated with each other so that in practice they comprise the same unit.
• the example in the description relates to a vehicle in which the clutch is operated by means of a clutch pedal.
• the clutch can instead be operated by operating mechanisms other than a pedal.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)
• Braking Arrangements (AREA)
• Mechanical Operated Clutches (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20387728

Family Applications (1)

Country Status (4)

Cited By (4)

Citations (4)

• 1992
  • 1992-11-06 SE SE9203315A patent/SE470517B/sv not_active IP Right Cessation
• 1993
  • 1993-10-27 DE DE69314051T patent/DE69314051T2/de not_active Expired - Fee Related
  • 1993-10-27 WO PCT/SE1993/000858 patent/WO1994011647A1/en active IP Right Grant
  • 1993-10-27 EP EP93924851A patent/EP0668971B1/en not_active Expired - Lifetime

Patent Citations (4)

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