Brake conditioning
09989118 ยท 2018-06-05
Assignee
Inventors
- Alastair Booker (Warwickshire, GB)
- Steve Cornforth (Warwickshire, GB)
- Ananda Haputhanthirige (Warwickshire, GB)
Cpc classification
F16D69/023
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F16D65/126
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B60B27/0063
PERFORMING OPERATIONS; TRANSPORTING
F16D2250/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B24B39/06
PERFORMING OPERATIONS; TRANSPORTING
B60B27/0052
PERFORMING OPERATIONS; TRANSPORTING
International classification
F16D69/02
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
B24B39/06
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A wheel carrier assembly (104) for a vehicle (110) is clamped on a frame (14) and a carbon composite brake disc 41 of the assembly is bedded by pneumatically applying the brake pads to the brake disc so as to heat the disc in cycles, the wheel carrier assembly then being removed from the frame and fitted to the vehicle.
Claims
1. A method of bedding a carbon composite material brake disc for use in a vehicle, the method comprising: mounting the brake disc to a support rig via a knuckle adapted to support the brake disc relative to a vehicle body via suspension components; rotatably driving the brake disc; and applying frictional engagement to a friction surface of the brake disc to frictionally raise a temperature of the brake disc for bedding conditioning thereof.
2. A method as claimed in claim 1, further comprising mounting the brake disc to the support rig via a wheel hub.
3. A method as claimed in claim 1, further comprising mounting the brake disc to the support rig together with a brake calliper and at least one brake pad.
4. A method as claimed in claim 3, further comprising mounting the brake calliper with at least one hydraulic brake seal associated with each of the at least one brake pad.
5. A method as claimed in claim 3, further comprising supplying pressurised air to the brake calliper to cause each of the at least one brake pad to frictionally engage with the brake disc.
6. A method as claimed in claim 5, further comprising supplying the pressurised air at a pressure of about: (a) 10 to 300 bar, (b) 20 to 100 bar, (c) 25 to 60 bar, (d) 30 to 50 bar, (e) 35 to 45 bar, (f) under 100 bar, (g) under 75 or under 60 bar, (h) over 20 bar, or (i) about 35, 40, or 50 bar.
7. A method as claimed in claim 5, further comprising providing the pressurised air from a source and increasing the pressure of the air supplied from the source.
8. A method as claimed in claim 1, further comprising conditioning the brake disc with a plurality of heat cycles, each heat cycle including a warming stage during which a reference temperature of the brake disc is increased and a cooling stage in which the reference temperature is decreased.
9. A method as claimed in claim 8, further comprising raising the reference temperature to a peak temperature and then lowering the reference temperature to a dropped temperature during each cycle, at least one peak temperature of at least one cycle being over 300 degrees C.
10. A method as claimed in claim 9, wherein the reference temperature is a surface temperature of the brake disc measured by a sensor.
11. A method as claimed in claim 9, further comprising providing brake pressure at a substantially constant or varying value to a calliper associated with the brake disc during each warming stage.
12. A method as claimed in claim 11, further comprising providing the brake pressure for between about 5% and 75% of the time during each cycle.
13. A method as claimed in claim 12, further comprising providing the brake pressure for a smaller proportion of time in at least one cycle with a higher peak temperature than in at least one cycle with a lower peak temperature.
14. A method as claimed in claim 1, further comprising using a motor to drive the brake disc rotationally at a start speed for the application of frictional heating to the brake disc.
15. A method as claimed in claim 14, wherein the start speed is in the region of about 250 to 2500 RPM.
16. A method as claimed in claim 15, wherein the start speed is selected to be equivalent to the rotational velocity of the brake disc when a vehicle to which the brake disc is to be fitted is travelling at a speed which is over 70 mph.
17. A method as claimed in claim 15, further comprising providing a flywheel rotationally connected to the brake disc, the flywheel being adapted to supply torque to the brake disc while the brake disc is being frictionally heated.
18. A method as claimed in claim 17, further comprising allowing the rotational speed of the brake disc and flywheel to decrease during frictional heating of the brake disc.
19. A method as claimed in claim 17, further comprising providing the flywheel with a mass moment of inertia of between 10 and 200 kgm.sup.2.
20. A method as claimed in claim 17, wherein the brake disc is for application to a vehicle having four road wheels with brakes and which is adapted to have a kerb weight of X kg, and in which the mass moment of inertia of the flywheel is between about (X/10) and (X/100) kgm.sup.2.
21. A method as claimed in claim 1, further comprising cooling the brake disc by directing a cooling air flow thereto.
22. A method as claimed in claim 1, further comprising providing the frictional engagement to the surface of the brake disc by engaging at least one brake pad therewith.
23. A method as claimed in claim 22, further comprising: securing the brake disc to the support rig via a wheel hub and the knuckle; and mounting the at least one brake pad in a brake calliper secured to the knuckle.
24. A method of assembling a motor vehicle, comprising: carrying out the method of claim 23; removing the knuckle, wheel hub, brake disc, brake calliper, and at least one brake pad all together as an assembly from the support rig; and then fitting the removed assembly to a motor vehicle.
25. A method of assembling a motor vehicle, comprising a method of bedding a carbon composite material brake disc as claimed in claim 1.
26. A wheel carrier assembly comprising an assembled knuckle, wheel hub, brake disc conditioned in accordance with claim 1, brake calliper, and at least one brake pad.
27. A motor vehicle including the wheel carrier assembly as claimed in claim 26.
28. A method of bedding a carbon composite material brake disc for use on a vehicle having a hydraulically operated calliper and brake pad assembly, the method comprising: assembling the calliper and brake pad assembly for use with and to frictionally engage a brake disc; rotating the brake disc relative to the calliper and brake pad assembly; applying air under pneumatic pressure into the calliper and brake pad assembly to frictionally engage the brake pad onto the brake disc; and maintaining at least one hydraulic brake seal in an operative position within the calliper and brake pad assembly while applying the air under pneumatic pressure.
29. A method of bedding a brake component for use in a vehicle, the method comprising: mounting a brake disc to a stationary support rig; providing a rotational shaft for driving the brake disc, the shaft including at least one articulated joint; providing a flywheel at least partially for driving the brake disc; fixing the flywheel to the stationary support rig via a bearing; and attaching one end of the shaft to the flywheel.
30. A method as claimed in claim 29, further comprising: mounting the brake disc on a splined wheel hub; and providing a splined connection between the wheel hub and the shaft.
31. A method as claimed in claim 29, further comprising providing the brake component as the brake disc.
32. A method of bedding a brake component, the method comprising: clamping at least a brake disc and wheel hub to a support rig; providing a source of motive torque for rotating at least the brake disc; and preventing the source of motive torque from operating unless an indicator of clamping security is provided.
33. A method as claimed in claim 32, further comprising establishing a torque setting state during the clamping which is representative of safe clamping in order to provide a signal for enabling operation of the source of motive torque.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The present invention may be carried out in various ways and a preferred embodiment of a method of bedding a brake disc for use in a vehicle and apparatus for the same will now be described by way of example with reference to the accompanying drawings in which:
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DETAILED DESCRIPTION
(12) As shown in
(13) A motor 18 is secured by a mount 20 to the frame 14 and is connected by a drive shaft 22 to a flywheel 28, the flywheel being mounted by bearings 32, which are secured by mounts 31, 33 to the frame 14. A drive shaft 34 connects the flywheel 28 via CV joints 36, 38 to a splined connection 40 with brake disc 41.
(14) The brake disc 41 is connected to the frame 14 via a wheel hub 100 and knuckle 102, the wheel hub and knuckle not being shown in
(15) As can be seen in
(16) As shown in
(17) When hydraulic fluid pressure is applied at the inlet 116, internal calliper supply paths 128 (
(18) As shown in
(19) The corner unit mount or clamping arrangement 42 as shown in
(20) Thus, upper 152 and lower 154 threaded screws may each be torqued up to reach respective predefined torques and therefore ensure that a predefined safe clamping is effected between the knuckle 102 and the frame 14. The screws 152, 154 may be torqued by the torque wrenches/readers 84 which may provide signals along torque data flow path 85 to system controller 54 which prevents operation of the motor 18 without receiving a signal indicative that the wheel carrier assembly 104 is in position and securely clamped with the torques on the screws 152, 154 set to predetermined amounts.
(21) As shown in
(22) As shown in
(23) Also as shown in
(24)
(25)
(26) In the example shown in
(27) First, the wheel carrier assembly 104 is clamped in position on the frame 14 as described above. Next, all persons leave the room 10 and the door 12 is shut and locked. Door lock/sensor 86 sends a signal along door lock data flow path 88 to the system controller 54. Using a master controller 200 located outside the room, an operator (not shown) sends a signal using the master controller 200 to the system controller 54 that bake bedding is to commence. The system controller 54 first checks via torque data flow path 85 that the clamp screws 152, 154 are sufficiently torqued by the torque/wrenches/readers 84. With the door locked and the wheel carrier assembly 104 securely clamped, the dust extractor nozzle 76/cyclonic filter/exhaust outlet 82 is switched on and the pneumatic intensifier 68 is ready for action with an internal solenoid 204 thereof being ready to switch on high pressure air supply along conduit 70. Likewise, optical infrared disc surface temperature sensor 63 is switched on as are the cooling fans/blowers 60.
(28) The controller 54 then causes the motor 18 to drive the shafts 22, 34 and the flywheel 28 and brake disc 41 up to an idle speed of approximately 550 rpm at point 300 in
(29) Next, the solenoid 204 of the pneumatic intensifier 68 is opened and the pressure on line 70 is almost immediately raised to approximately 37 bar thereby applying the brake pads 46, 48 frictionally to the brake disc 41. Torque on the motor 18 is almost simultaneously switched off and over a period of approximately 20 seconds, the rotational speed of the spinning components is slowed down by the action of brake pads 46, 48 on the brake disc 41 approximately linearly to about 600 rpm. During this period, the brake disc temperature peaks at point 304 in
(30) Then, the solenoid 204 is closed and the line 70 is vented and after a short speed transient 304 rotational speed is set to approximately 600 rpm.
(31) Then, the brake disc temperature reduces to about 225 degrees C. At the end of the cycle C1, the next cycle of the eight cycles shown commences. During each cycle, the rotational speed is raised to just over 1400 rpm and it is then slowed during the brake applied period to approximately 600 rpm. As the cycles progress, the peak temperature of the disc surface in cycle 2 is approximately 375 degrees C., the next cycle has a peak temperature of about 425 degrees C., the next cycle has a peak temperature of approximately 600 degrees C. and the following cycles all have peak temperatures of between 600 and about 750 degrees C. During each cycle, the temperature drops from the peak temperature by about 150 to 225 degrees C. As the cycles progress through the series thereof, the disc temperature generally becomes higher in average terms as well as in terms of peak temperature and lowest cycle temperature. Additionally, the proportion of the cycle during which the brakes are applied by the application of the approximately 37 bar of pressure along the line 70 becomes smaller, this being in order to avoid further increased temperature and to control temperature generally to a range within the later cycles of about 400 to 650 degrees C.
(32) After the eighth cycle, the rotational speed is set to 100 RPM in a cooling mode. Once disc temperature lowers to 50 degrees C., the rotation is stopped and door lock/sensor 86 is unlocked to permit access to the room 10. This prevents any possibility of the operator or anybody else being burnt by contact with hot parts.
(33) By the end of all the cycles, the material of the carbon composite brake disc 41 is chemically changed and is made substantially harder and also impermeable to water.
(34) It is also noted, as shown in
(35) In a modification of the apparatus, four frames 14 and all of the other apparatus shown in the
(36) With a static rig (frame 14 and other components) the apparatus and method of bedding described above provide a higher quality bedded disc than available in the prior art due to the use of the more repeatable and objective bedding procedure conducted in a stable environment. The process is also safe, cost effective and is less harmful to the environment than prior methods. The clamping system advantageously holds the corner unit/wheel carrier assemble 104 securely and without damaging it. The knuckle 102 can be provided in a configuration ready for assembly onto the suspension components of a vehicle, including, for example Nylon (trade mark) inserts and these are not damaged by the clamps. The clamping arrangement may involve a sliding bed (not shown) to allow the wheel carrier assembly 104 to be slid to engage the splined shaft 34, the shaft 34 including the CV joints 36, 38 at or near each end so as to allow for the transmission of torque without loss from the flywheel due to the positioning of the wheel carrier assembly 104, irrespective of the position in which the wheel carrier assembly 104 is fixed. This greatly simplifies the mounting of the wheel carrier assembly as it removes the need to accurately place the corner unit in the bedding machine 17 in relation to the centre line of the flywheel 28 and variable tolerances in the manufacture of the components of the wheel carrier assembly 104 can be accommodated. Thus, vibration due to an out of balance/out of position wheel corner unit 104 can be eliminated or minimised.
(37) The drive shaft 34 may wear after a considerable number of multiple operations and advantageously can easily be changed as part of regular preventative maintenance of the machine 17.
(38) A considerable amount of kinetic rotational energy is generated during the process and the components described above enable the corner unit/wheel carrier assembly 104 to be secured robustly into the bedding machine 17 and also ensure that the machine 17 cannot be started unless the corner unit 104 is fully clamped into position, and the safety features also ensure that the room must be evacuated and the door 12 locked before use. The use of tightenable threaded screws or bolts 152, 154 ensures that correct clamp loads are applied to secure the corner unit/wheel carrier assembly 104 in position. Both the torque and angle of these screws may be controlled using an Atlas Copco DC (registered trade mark) tool 84 in order to interlock the machine 17 to prevent it from running unless all of the screws have been tightened correctly.
(39) The system allows standard dried shop floor compressed air at 6 or 8 bar to pass into the pneumatic intensifier 68 which pressurises the air to the required pressure for the line 70, which may be somewhere between 30 and 50 bar, about 37 bar in the example of
(40) The bedding process is also made safe by the interlock from the door lock/sensor 86 which prevents operation unless the door is closed/locked and nobody is in the room 10. The system controller 54 and master controller 200 which may be a PC based system operate the motors and pneumatics. The system controller 54 may comprise a programmable logic controller (PLC).
(41) An operator may start the machine 17 by entering vehicle details into the master controller 200 using a bar code scanner so as to ensure that the correct parameters are used for the discs in question as different types and sizes of discs may be bedded by the machine. The flywheels may then be accelerated using the powerful electric motors 18, for example to the just over 1400 rpm speed shown in
(42) The flywheels may represent a similar amount of rotational inertia to that which would be generated by a vehicle to which the wheel carrier assemblies are to be fitted while it is travelling at approximately 100 to 150 mph. The electric motors are relatively powerful and are capable of accelerating the flywheel to operating speed (say 1200 or just over 1400 rpm, in about 20 seconds). This short period is advantageous since it prevents heat being lost from the disc 41 and soaking into the calliper 44 which could undesirably heat up the calliper, since the calliper must remain at about 110 degrees or less so as to prevent damage to the hydraulic fluid seals 108 which are made of silicone. The process is controlled by the PC or master controller 200 to define sequence of accelerations, decelerations and cool down runs until the desired bedded brake surface is achieved as appropriate to the vehicle discs 41 used. The brake dust generated by the process is conveniently removed and filter as discussed above.
(43) Advantageously, the end of the bedding process may involve a cool down process in which the discs are turned at about 100 RPM while the air blowers 61, 60 are used to assist in cooling. This therefore will occur after the final cycle shown in
(44) The optical infrared sensor 63 monitors disc surface temperature which is recorded against the vehicle by the PC 200 for quality and traceability purposes. In the specific embodiment, the IR sensor 63 is not used for close loop temperature control during the bedding procedure although such control could be used in other embodiments.
(45) The process may be compressed into a very much shorter time cycle than when using a car on a test track to bed the brakes in and the energy requirements for the bedding in process are also lowered. The process can be conducted independently of weather conditions in a stable environment, improving repeatability and also removing any damage which may be caused to the discs before bedding in by moisture which may be picked up on a test track. The process can also be conducted at any time of day as it does not cause a local nuisance, such as by way of noise, to neighbours. The bedding process does not require a vehicle to complete it so no vehicle damage is caused during the bedding process. The heat generated by the bedding process can also be captured and use to heat the building housing the apparatus 17 to lower the energy used. Furthermore, new or replacement service parts may be bedded in before they are sent off to dealers, resulting in large saving in time and costs for aftersales functions.
(46) There now follows a discussion of a number of features relating to the preferred embodiments
(47) (A) In some preferred embodiments: Flywheel size/mass (e.g. moment of inertia) are capable of simulating equivalent vehicle mass of about 1700-1900 Kg, advantageously enabling simulation of the rotational inertia of such a vehicle under heavy braking. Flywheels used for bedding front disks for such a vehicle can be optionally rated at 75 kgm.sup.2. Flywheels used for bedding rear disks for such a vehicle can be optionally rated at 50 kgm.sup.2. Motor torque required is selected so as to be advantageously capable of accelerating the respective flywheel as quickly as reasonably possible to prevent an undesirably large loss of heat in system and heat transfer into caliper. Rated motor torque in some embodiments is selected high enough to allow acceleration of 75 kgm.sup.2 and 50 kgm.sup.2 flywheels to 1600 RPM in <20 secs. Rated motor power in some embodiments may be 90 KW for front and 60 KW drives for rear discs with torque of about 537 Nm and 358 Nm respectively, 7.16 ms/2 acceleration and 23.4 secs from 0-1600 RPM.
(48) (B) In some embodiments some features may be varied or tuned in accordance with the following: Maximum rotational drive speed, useful for simulating a vehicle driving at a certain speed, may in some embodiments be: Up to 1600 rpm on each shaft (e.g. when there are 4 machines set up in a room in parallel with a shaft/motor/flywheel/frame for each), enough for significant headroom above setups that may normally only require speeds at about 50 to 70% of this speed. Pressure to be provided by pressure intensifier, accumulator (plenum) and solenoid valve based system to allow clamping of discs. Up to 50 bar to be made available via solenoid valve activation, optionally having two circuits with regulators to allow two separate pressures to be used in test modes. Cooling Air Flow Speed, required to cool discs and callipers both during testing/bedding but also after running. Up to approx. 40 mph. Bedding profile The bedding machine optionally and desirably has capability of running a set program of accelerations, decelerations etc. according to a pre-defined sequence.
(49) (C) Discussion of a number of parameters employed in a specific example in accordance with the embodiment described above with reference to the drawings: Drive speed. Various drive speeds may be employed, for example between 800-1100 RPM or up to about 1500 RPM. Clamping Pressure 45 bar pneumatic pressure. Cooling air flow speed Fan motor set at 45 Hz (90% of max. capability). Cooling air flow direction For front wheel brake corner unitsAir directed directly onto surface of disc as it enters calliper (see
(50) Instead of bedding a carbon composite material brake disk, the method and apparatus described in the embodiments hereof may alternatively be employed for conditioning other frictional components or other carbon composite materials, or components such as brake disks or pads made from other materials.
(51) Various modifications may be made to the embodiments described above without departing from the scope of the invention defined by the accompanying claims.