Installation Manual

Electrical & Electronic Application And Installation Manual
Production Release Version 1.0
Page 229
type is recommended for use on applications with a constant operating speed
and applications with manual transmissions. The all speed governor is also
known as ‘variable speed’ or ‘full range engine speed governor’
The governor strategy calculates the fuel quantity required to keep the actual
engine speed equal to the desired engine speed. The desired engine speed
is the output of the throttle arbitration strategy defined in the Engine speed
demand section 11.0 of this document. All speed refers to the fact that the
engine governor operates across the full engine speed operating range. The
governor strategy has control parameters classed as governor gains, which
determine the engine response and engine stability. These gains are ‘tuned’
to ensure that they are configured for optimum performance under both
steady state and transient conditions.
Under default conditions the engine is set to operate with isochronous
governing across the engine speed range, during which the engine fuelling is
bound by the engine torque curve. Note that the engine may not be capable
of reaching the torque fuel limit curve in some circumstances. For example, if
the turbocharger is not providing the required boost pressure, then the fuel will
be limited so that the engine does not emit black smoke.
Engines can however be configured to operate with a level of engine droop,
under the torque curve. Droop is the variation of engine speed as load is
applied. For example, if an engine has 10% droop and is running at 1500RPM
without load, then as load is applied the operator will feel and hear the engine
speed gradually decreasing. This is represented by the diagonal dotted lines
under the torque curve in the diagram below.
When the load reaches the torque limit curve of the engine, the engine will lug
back along the curve.
Note that droop values can be assigned to the multi-position throttle switch
input, PWM accelerator pedal/lever input and the TSC1 speed demand over
J1939. Droop does not apply, however to the PTO mode, which always
operates isochronously (0% Droop)
The high speed governor (governor run-out) is governed by the relationship
between the rated engine speed (this is fixed for each rating and cannot be
altered) and the chosen high idle speed. High Idle is the maximum speed that
the engine will reach. Note that this is on the bare engine and when installed
in an application, it may not be possible to reach this speed due to the
parasitic loads of the driven equipment. The range of possible high idle
speeds is defined by the parameters, High Idle Lower limit (HILL) and High
Idle Upper Limit. (HIUL). High Idle cannot be specified to be less than Rated
Speed (RS) and cannot exceed RS+12%. This HIUL is specified to ensure
governor stability is maintained throughout the engine operating range.