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1、BRITISH STANDARD AUTOMOBILE SERIES BS AU 50-1.2.3:1993 ISO 9948:1992 Tyres and wheels Part 1: Tyres Section 2: Commercial vehicle tyres Subsection 2.3 Method of measuring rolling resistance UDC 629.114.3/.5.012.55:531.45.083 Licensed Copy: London South Bank University, London South Bank University,
2、Sat Dec 09 02:07:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 50-1.2.3:1993 This British Standard, having been prepared under the direction of the Automobile Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 May 1993 BSI 12-1999 T
3、he following BSI references relate to the work on this standard: Committee reference AUE/4 Draft for comment 91/71575 DC ISBN 0 580 21747 7 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Automobile Standards Policy Committee (AUE/-) to
4、Technical Committee AUE/4, upon which the following bodies were represented: Agricultural Engineers Association Automobile Association British Industrial Truck Association British Pressure Gauge Manufacturers Association British Rubber Manufacturers Association Bus and Coach Council Department of Tr
5、ansport Freight Transport Association Institute of Road Transport Engineers (Inc) Motor Cycle Industrys Association of Great Britain Ltd. Motor Industry Research Association National Tyre Distributors Association Retread Manufacturers Association Road Haulage Association Ltd. Society of Motor Manufa
6、cturers and Traders Ltd. Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:07:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 50-1.2.3:1993 BSI 12-1999i Contents Page Committees responsibleInside fron
7、t cover National forewordii 1Scope1 2Definitions1 3Test methods1 4Test equipment1 5Test conditions2 6Test procedure2 7Data interpretation3 8Data analysis4 Annex A (normative) Test equipment tolerances6 Annex B (informative) Optional test conditions7 Annex C (informative) Measurement methods of momen
8、t of inertia for drum and tyre assembly Deceleration method7 Figure 1 Free-body diagram of tyre/drum system, assuming no bearing and windage losses3 Figure C.1 Arrangement8 Figure C.2 Spring method9 Figure C.3 Bifilar pendulum (rope) method9 Table B.17 Licensed Copy: London South Bank University, Lo
9、ndon South Bank University, Sat Dec 09 02:07:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 50-1.2.3:1993 ii BSI 12-1999 National foreword This Subsection of this Part of BS AU 50 has been prepared under the direction of the Automobile Standards Policy Committee. It is identical with ISO 9948:1
10、992 Truck and bus tyres Methods of measuring rolling resistance, published by the International Organization for Standardization (ISO). Other Parts of this standard are as follows: Part 2: Wheels and rims; Part 3: Valves; Part 4: Rim profiles and dimensions. A British Standard does not purport to in
11、clude all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pag
12、es i and ii, pages 1 to 9 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:
13、07:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 50-1.2.3:1993 BSI 12-19991 1 Scope This International Standard specifies methods for measuring rolling resistance, under controlled laboratory conditions, for new pneumatic tyres designed primarily for use on trucks and buses. The relationship b
14、etween values obtained and the fuel economy of the vehicle is undetermined, and such values are not intended to be used to indicate levels of performance or quality. This International Standard applies to all truck and bus tyres. It enables comparisons to be made between the rolling resistance of ne
15、w tyres when they are free-rolling straight ahead, in a position perpendicular to the drum outer surface, and in steady-state conditions. In measuring tyre rolling resistance, it is necessary to measure small forces in the presence of much larger forces. It is, therefore, essential that equipment an
16、d instrumentation of appropriate accuracy be used. 2 Definitions For the purposes of this International Standard, the following definitions apply. 2.1 rolling resistance, Fr loss of energy (or energy consumed) per unit of distance NOTE 1The SI unit conventionally used for the rolling resistance is t
17、he newton metre per metre (Nm/m). This is equivalent to the drag force in newtons (N). 2.2 rolling resistance coefficient, Cr ratio of the rolling resistance, in newtons, to the load on the tyre, in newtons. This quantity is dimensionless and is derived as follows: 2.3 capped inflation process of in
18、flating the tyre and allowing the inflation pressure to build up, as the tyre is warmed up while running 2.4 regulated inflation process of inflating the tyre to the required pressure independent of its temperature, and maintaining this inflation pressure while the tyre runs under load. This is most
19、 commonly done by using a regulated pressure source attached to the tyre through a rotating union. (See Annex B.) 2.5 parasitic loss loss of energy (or energy consumed) per unit distance excluding tyre losses, and attributable to aerodynamic loss, bearing friction and other sources of systematic los
20、s which may be inherent in the measurement 2.6 skim reading type of parasitic loss measurement, in which the tyre is kept rolling, without slippage, while reducing the tyre load to a level at which energy loss within the tyre itself is virtually zero 2.7 machine reading type of parasitic loss measur
21、ement, involving losses of the test machine, exclusive of losses in the rotating spindle which carries the tyre and rim 2.8 moment of inertia (see Annex C) 3 Test methods The following alternative measurement methods are given in this International Standard. The choice of an individual method is lef
22、t to the tester. For each method, the test measurements shall be converted to a rolling resistance force acting at the tyre/drum interface. a) Force method: the reaction force at the tyre spindle. b) Torque method: the torque input to the test drum. c) Power method: the power input to the test drum.
23、 d) Deceleration method: the deceleration of the test drum and tyre assembly. 4 Test equipment 4.1 Drum specifications 4.1.1 Diameter The test dynamometer shall have a cylindrical flywheel (drum) with a diameter of between 1,7 m and 3 m inclusive. It should be noted that the results are different; s
24、ee 8.3 for drum diameter correction for comparisons, if necessary. 4.1.2 Surface The surface of the drum shall be smooth steel or textured, and shall be kept clean. For the textured drum surface, see B.4. Cr rolling resistance test load - -= Licensed Copy: London South Bank University, London South
25、Bank University, Sat Dec 09 02:07:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 50-1.2.3:1993 2 BSI 12-1999 4.1.3 Width The width of the drum test surface shall exceed the width or the test tyre tread. 4.2 Test rim The tyre shall be mounted on a test rim, as specified in Annex A. 4.3 Load, ali
26、gnment, control and instrumentation accuracies Measurement of these parameters shall be sufficiently accurate and precise to provide the required test data. The specific and respective values are shown in Annex A. 4.4 Thermal environment 4.4.1 Reference conditions The reference ambient temperature,
27、as measured on the rotational axis or the tyre, 1 m away from the plane touching the nearest tyre sidewall, shall be 25 C. 4.4.2 Alternative conditions If the reference temperature cannot be obtained, the rolling resistance measurement shall be corrected to standard temperature conditions in accorda
28、nce with 8.2. 4.4.3 Drum surface temperature Care should be taken to ensure that the temperature of the test drum surface is approximately the same as the ambient temperature at the beginning of the test. 5 Test conditions The test consists of a measurement of rolling resistance in which the tyre is
29、 inflated and the inflation pressure allowed to build up (i.e., “capped air”). 5.1 Test speeds 5.1.1 Test speed for load index 122 and above The value shall be obtained at a drum speed of 80 km/h for tyres with speed symbols K to M inclusive and at 60 km/h for speed symbols F to J inclusive. 5.1.2 T
30、est speeds for load index 121 and below The values shall be obtained at drum speeds of 80 km/h, and if required, 120 km/h. 5.2 Test load The standard test load shall be computed from 85 % of the maximum single load capacity of the tyre and shall be kept within the tolerance specified in Annex A. 5.3
31、 Test inflation pressure The inflation pressure shall be the inflation pressure, specified by the tyre manufacturer concerned, corresponding to the maximum single tyre load capacity. The inflation pressure shall be capped with the accuracy specified in A.4.1. 5.4 Duration and velocity When the decel
32、eration method is selected, the following requirements apply: a) for duration, %t, the time increments shall not exceed 0,5 s; b) any variation of the test drum velocity shall not exceed 1 km/h. 5.5 Optional conditions If the sensitivities of load, inflation or velocity are desired, the additional i
33、nformation given in Annex B should be consulted. 6 Test procedure The test procedure steps described below are to be followed in the sequence given. 6.1 Break-in To ensure repeatability of measurements, an initial break-in and cooling period is required prior to the start or the test. Such a break-i
34、n should be carried out on a vehicle or on a test drum of at least 1,7 m in diameter. 6.2 Thermal conditioning Place the inflated tyre in the thermal environment of the test location for the time necessary to achieve thermal equilibrium which is generally reached after 6 h. 6.3 Pressure adjustment A
35、fter thermal conditioning, the inflation pressure shall be adjusted to the test pressure and verified 10 min after the adjustment was made. 6.4 Warm-up The tyre shall be run at constant test velocity until reaching a stabilized steady-state value of rolling resistance. Recommendations for warm-up pe
36、riods are given in Annex B. 6.5 Measurement and recording The following shall be measured and recorded (see Figure 1): a) test velocity, Un; b) load on the tyre normal to the drum surface, Lm; c) test inflation pressure: 1) initial, as defined in 6.3, 2) final, for capped inflation; Licensed Copy: L
37、ondon South Bank University, London South Bank University, Sat Dec 09 02:07:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 50-1.2.3:1993 BSI 12-19993 d) the driving torque on the drive shaft, Tt, the tyre spindle force, Ft, the input power, V A, or the deceleration of the test drum/tyre/wheel a
38、ssembly, %/%t, depending on the method; e) distance, rL (see 7.2.1); f) ambient temperature, tamb; g) test drum radius, R; h) test method chosen; i) test rim (designation and material). 6.6 Measurement of parasitic losses Determine parasitic losses by a procedure given in 6.6.1, 6.6.2 or 6.6.3. 6.6.
39、1 Skim reading a) Reduce the load to maintain the tyre at the test velocity without slippage to, for example, 50 N. b) Record the spindle force, Fp input torque, Tp, or the power, whichever applies. c) Record the load on the tyre normal to the drum surface, Lp. 6.6.2 Machine reading a) Remove the ty
40、re from the test drum surface. b) At the test velocity, Un, record the input torque, Tp, the power, or the test drum deceleration, whichever applies. 6.6.3 Deceleration method a) Remove the tyre from the test drum surface. b) Record the deceleration of the test drum, %o/%t, and that of the unloaded
41、tyre, %po/%t. 7 Data interpretation 7.1 Subtraction of parasitic losses The parasitic losses shall be subtracted as shown in 7.1.1, 7.1.2 or 7.1.3. 7.1.1 Skim reading Subtract the skim reading from the test measurement. 7.1.2 Machine reading Subtract the machine reading from the test measurement. 7.
42、1.3 Parasitic losses Calculate the parasitic losses, Fp, in newtons, as Figure 1 Free-body diagram of tyre/drum system, assuming no bearing and windage losses where IDis the test drum inertia in rotation, in kilogram metres squared; Ris the test drum surface radius, in metres; vois the test drum ang
43、ular velocity, without tyre, in radians per second; %tois the time increment chosen for the measurement of the parasitic losses without tyre, in seconds; ITis the tyre and wheel inertia in rotation, in kilogram metres squared; Rris the tyre rolling radius, in metres; pois the tyre angular velocity,
44、unloaded tyre, in radians per second. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:07:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 50-1.2.3:1993 4 BSI 12-1999 7.2 Rolling resistance calculation The net values of driving torque, spindle force, power
45、or deceleration are to be converted to rolling resistance, Fr, expressed in newtons, using the appropriate method, as shown in 7.2.1 to 7.2.4. 7.2.1 Force method The rolling resistance, Fr, in newtons, is calculated with the equation Fr= Ft1 + (rL/R) 7.2.2 Torque method The rolling distance, Fr, in
46、newtons, is calculated with the equation 7.2.3 Power method The rolling resistance, Fr, in newtons, is calculated with the equation 7.2.4 Deceleration method The rolling resistance, Fr, in newtons, is calculated with the equation Annex C gives guidelines and practical examples to measure the moments
47、 of inertia for the deceleration method. 8 Data analysis 8.1 Rolling resistance coefficient The rolling resistance coefficient, Cr, is calculated by dividing the rolling resistance by the load on the tyre: 8.2 Temperature correction If measurements at temperatures other than 25 C are unavoidable (on
48、ly temperatures not less than 20 C nor more than 30 C are acceptable), then a correction for temperature shall be made using the following equation, where Fr25 is the rolling resistance at 25 C, in newtons: Fr25= Fr1 + K(tamb 25) where Ftis the tyre spindle force, in newtons; rLis the distance from
49、the tyre axis to the drum outer surface under steady-state conditions, in metres; Ris the test drum radius, in metres. where Tis the input torque, in newton metres; Ris the test drum radius, in metres. where Vis the electrical potential applied to the machine drive, in volts; Ais the electric current drawn by the machine drive, in amperes; Unis the test drum velocity, in kilometres per hour. where IDis the test drum inertia in rotation, in kilogram metres squared; Ris the test drum s