[Code of Federal Regulations]
[Title 40, Volume 30]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1065.105]
[Page 653-654]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 1065_TEST PROCEDURES AND EQUIPMENT--Table of Contents
Subpart B_Equipment and Analyzers
Sec. 1065.105 Dynamometer and engine equipment specifications.
(a) The engine dynamometer system must be able to control engine
torque and speed simultaneously over the applicable test cycles within
the accuracies specified in Sec. 1065.530. If your dynamometer cannot
meet the accuracy requirements in Sec. 1065.530, you must get our
approval before using it. For transient testing, issue command set
points for engine torque and speed at 5 Hz or greater (10 Hz
recommended). Record feedback engine torque and speed at least once
every second during the test. In addition to these general requirements,
make sure your engine or dynamometer's readout signals for speed and
torque meet the following accuracies for all testing:
(1) Engine speed readout must be accurate to within 2 percent of the absolute standard value. A 60-tooth (or
greater) wheel in combination with a common mode rejection frequency
counter is considered an absolute standard for engine or dynamometer
speed.
(2) Engine flywheel torque readout must meet one of the two
following standards for accuracy:
(i) Within 3 percent of the NIST true value
torque (as defined in Sec. 1065.315).
(ii) The following accuracies:
------------------------------------------------------------------------
Engine flywheel torque
If the full-scale torque value is... readout must be within...
------------------------------------------------------------------------
T <= 550 ft-lbs........................... 2.5 ft-
lbs. of NIST true value.
-------------------------------------------
550 < T <= 1050 ft-lbs.................... 5.0 ft-
lbs. of NIST true value.
-------------------------------------------
T 1050 ft-lbs. 10.0
ft-lbs. of NIST true value.
------------------------------------------------------------------------
(3) Option: You may use internal dynamometer signals (such as
armature current) to measure torque if you can show that the engine
flywheel torque
[[Page 654]]
during the test cycle conforms to paragraph (b)(2) of this section. Your
measurements must compensate for increased or decreased flywheel torque
because of the armature's inertia during accelerations and decelerations
in the test cycle.
(b) To verify that the test engine has followed the test cycle
correctly, collect the dynamometer or engine readout signals for speed
and torque so you can statistically correlate the engine's actual
performance with the test cycle (see Sec. 1065.530). Normally, to do
this, you would convert analog signals from the dynamometer or engine
into digital values for computer storage, but all conversions must meet
two criteria:
(1) Speed values used to evaluate cycles must be accurate to within
2 percent of the readout value for dynamometer or engine speed.
(2) Engine flywheel torque values used to evaluate cycles must be
accurate to within 2 percent of the readout value for dynamometer or
engine flywheel torque.
(c) You may combine the tolerances in paragraphs (a) and (b) of this
section if you use the root mean square (RMS) method and refer
accuracies of the RMS values to absolute-standard or NIST true values.
(1) Speed values used to evaluate cycles must be accurate to within
2.8 percent of the absolute standard values, as
defined in paragraph (a)(1) of this section.
(2) Engine flywheel torque values used to evaluate cycles must be
accurate to within 3.6 percent of NIST true
values, as determined in Sec. 1065.315.