FIELD OF THE INVENTION
The present invention generally relates to hydraulic excavators. More particularly,
the invention relates to an improved method to accurately and precisely operate
an engine control system (ECS) of a Hydraulic Excavator.
BACKGROUND OF THE INVENTION
Hydraulic excavators are used for digging and handling bulk materials in mines
and in such applications, it is essential that the machine fuel consumption should
be optimized and the machine running cost should be reduced to cope up the
ever increasing fuel cost day by day. It has also become important to control
pollution by reducing burning of fuel.
To address the above issue, it is easily recognized that an accurate and precise
engine governing system is desirable.
However, to provide precise engine control by ESC, the prior art have focused on
introducing A/I + A/D feature along with work modes like ECO and HP. In
contrast, experimentation by the present invention has shown that
implementation of Default ECO-mode and Default A/I (standard feature) mode
gives further fuel economy for regular machine operation.

According to the prior art the engine RPM is controlled mechanically through an
accelerator lever along with mechanical au to-idle system.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved method to
accurately and precisely operate an engine control system (ECS) of a Hydraulic
Excavator.
Another object of this invention is to propose an improved method to accurately
and precisely operate an engine control system (ECS) of a Hydraulic Excavator
which reduce fuel consumption and enhances engine life by introducing A/I, A/D,
ECO (Default) and HP modes.
A further object of the invention is to propose an improved method to accurately
and precisely operate an engine control system which allows a precise RPM
control and achieves fuel economy with respect to utilization of the machine in
actual operation.
A still further object of the invention is to propose an improved method to
accurately and precisely operate an engine control system in which the
electronic control system (ECS) uses microcontroller, engine control dial and
pressure sensors to implement the improved method.

SUMMARY OF THE INVENTION
Accordingly, it is being provided with improved method to operate and control
the engine accurately and precisely through the and control system (ECS) of a
Hydraulic Excavator. The object of this invention is to control the Engine RPM
electro-mechanically as well as to regulate the high set RPM to intermittent RPM
known as Auto Idle (A/I), Auto Deceleration (A/D) RPM to reduce fuel
consumption when the machine is in idle condition, after a pre specified time
(Mr.Umapathy sir suggested not to put any values).
The method comprises using a plurality of arranged pressure sensors on
hydraulic control valve ports of the extravator to sense the pilot pressure during
machine operation. The main controller of the system receives signal relating to
the machine usage and accordingly controls the fuel flow, through stepper
motor. Thus, the engine RPM is efficiently regulated based on the machine
working load which substantially reduces the fuel consumption. Moreover, due to
the presence of various work modes for example, ECO (Economy) and HP (High
Power), the fuel consumption is further improved. Through the Electronic ECS,
the mode and various RPM modes can be achieved by the electronic controller
using multiple switch input (operator's interface) fitted on the panel. The ECS is
a dynamic method to achieve fuel economy automatically through the electronic
controller controlled by software without depending on the operator intervention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1.0 shows input/output details of the controller.
Figure 2.1 and 2.2 - shows a block diagram of the Engine Control System (ECS).
Figure 3.0 - shows characteristic curve for ECO mode control.
Figure 4.0 - shows characteristic curve for Auto Idle + Auto Deceleration control.
Figure 5 - shows a characteristic curve between the engine speed Vs control
lever.
Figure 6 - illustrates a Stepper Motor.
Figure 7.1 - shows a photographic view of the micro controller of the ECS.
Figure 7.2 - shows a relay PWN and DC/DC Converter of the ECS.
Figure 7.3 - shows a Load Dump Module.
Figure 8 - shows an overall layer of the stepper motor mounting.
Figure 9 - shows an overall layout of the Diagnostic Tool.

DETAIL DESCRIPTION OF THE INVENTION
The ECS consists of a micro controller (5), a DC to DC Voltage converter (9), at
least two Stepper Motor driving relays (7), a Load dump module (LDM) (10),
learning switch and switch box (4) (Engine control dial, Auto Idle switch and
Mode selection switch), a Stepper motor (8), at least two pressure sensors (6)
with continuous signal output (24V) fitted on a control valve. The continuous
output of the sensors (6) goes to zero Volt, after a pre specified time.
The ECS has two functional modes as Mode selection function and Auto Idle
function.
Mode Selection functions: This function enables a user to select the mode either
"HP" or "ECO" mode through a mode selection switch (3). In mode "HP", the
machine operates at full speed RPM (at high RPM). In mode "ECO", the machine
operates at slightly lower speed RPM compared to mode "HP". This enables the
user to select the mode depending on application for optimal fuel consumption.
In both these modes, the machine RPM drops by a prescribed level from high
rpm after a delay of preceding time in-order to reduce the fuel consumption,
provided the machine is idle for more than specified time. This feature is known
as Auto Deceleration (Auto deceleration) and activated by default in both the
modes.
Auto Idle (A/I + A/D) function: This function further reduces the Engine RPM,
from Auto deceleration RPM to Auto Idle RPM, to reduce the fuel consumption
compared to Auto deceleration RPM, provided the control levers are left idle for
more than the prescribed time (includes Auto Deceleration time). This function

can be enabled by means of an Auto Idle switch (2) provided in the switch box
(4) and can be activated in both the modes (HP and EP).
a) Basic outline of the ECS system:
The controller of the ECS system is used to control the engine based on
signals from the engine control dial, the switches and the sensors. After
processing all the input signals in the logic circuit, the controller sends control
signals to the stepper motor driving relays and in turn to the stepper motor.
The basic components used in the ECS are as below:
I. Stepper motor (8)
II. Pressure sensors (6)
III. Switch box (4)
IV. Relay: PWM (7)
V. Relay: D/C-D/C converter (9)
VI. Controller (5)
VII. Load dump module (10)
According to the invention, when the pilot levers is operated, the engine RPM
rises according to the set value of the engine control dial including the selected
mode which interalia enhances the life of the engine.
The machine has two different modes for operation namely "HP-High power
mode, and the ECO-economy mode".

The auto deceleration (A/D) and auto idling (A/I+A/D) feature is to reduce the
fuel consumption by reducing the high RPM by a set level.
• This feature gets enabled when either of the pilot levers is idle for more
than a pre-set time.
• This feature would be default in both "High Power and Economy" mode.
• When either of the pilot levers is operated, the machine RPM shoots back
up to a high RPM with respect to the mode selected.
• The auto idling feature (A/I + A/D): further reduces the fuel consumption
by reducing engine RPM further.
• This feature gets enabled only when the Auto idle switch (2) is turned ON.
• The machine comes into this mode when either of the pilot levers is idle
for more than a prescribed time of idleness, which interalia includes the
auto deceleration time.
• When either of the pilot levers is operated, the machine RPM shoots back
up to a high RPM with respect to the mode selected and Engine control
dial.

(i) Status Display:
• The diagnostic display tool, enabled with a diagnostic software can be
connected to the controller through harness. The display unit gets
powered up by machine battery power and displays "Diagnostic tool"
home page. An indicator provided on the unit blinks in green-indicating
that the display unit is powered up. Display unit home page displays
previous hours and minutes that the machine had worked/clocked. Now
by pressing the forward direction arrow the Home page Status shows
the Ignition switch, HP and ECO mode. Auto idle switch ON/OFF
condition. Auto idle and Auto Deceleration ON/OFF condition, Alternator
"WL" signal (S/L) and Learning switch ON/OFF Indication. On the same
page, one can see the engine control dial voltage and stepper motor
sensor (EC sensor) voltage in m volts.
• Green indication with description in respective switch block indicates that
the corresponding signal is ON.
• When the indication is white, respective switch function is OFF.
• Now by pressing the forward direction arrow key, the "Fault-1" page
showing that the status can be viewed.

(ii) System Diagnostic
• "Fault-1" page displays EC Dial Sensor and EC Motor Sensor conditions
along with the fault indicator.
• If the fault indicator turns 'RED" then the corresponding sensor is faulty
or no signal.
• In such case the actual value of the sensors does not vary and remains
constant or zero value as indicated.
• When the fault indicator is OFF, the real values are indicated in actual
values of the sensor.
• Respective fault indicator will on "RED" when either the EC dial or EC
motor sensor is faulty and gets reset only when the respective fault is
rectified.
• Now by re-pressing in the forward direction key once again, the display
unit is turned back to the home page "Diagnostic tool".
(iii) Engine rpm setting using the diagnostic tool:
Engine rpm can be set manually through the diagnostic tool and the tool can be
used to set the engine rpm, only when the engine FIP spring force is more than
12 Kg force. This implies that the program is re-mapped into the controller by
using the Diagnostic tools.

(iv) Stepper motor home position adjustment:
The stepper motor as supplied having its home position set. The motor responds
to the controller only if the EC motor sensor output signal voltage is within a
specified range.
Any external forces applied to the stepper motor shaft, results in a disturbed
home position. A motor home position is said to be shifted, if the EC angle
sensor voltage is less/ more than the specified value, when the machine is at low
idle or when the EC dial is at low idle position. In such cases, the motor does not
rotate as per the controller commands, instead it sounds a humming tune and
does not rotate.
This humming tune can be heard at the motor end when the engine is OFF and
EC dial is at max position with Ignition key ON.
Now by connecting the Diagnostic tool to the display unit connector in the
harness and putting the learning switch to ON mode (Learning switch status on
display unit will become "ON" on status page), the home position or the faulty EC
angle sensor voltage can be adjusted by selecting either "HI" or "LO" button on
the display screen.
The Engine Control System (ECS) uses the machine Controller, the Engine
Control Dial, the pressure sensors to perform the desired operation. The overall
objective is to have a precise RPM control and achieve the fuel economy with
respect to utilization of the machine in actual operation.

WE CLAIM :
1. An improved method to accurately and precisely operate an engine control
system (ECS) of a Hydraulic Excavator, the electronic control system
comprising at least one micro controller (5); at least two pressure
sensors (6) with continuous signal output disposed on a control valve; a
DC-DC converter (9); a stepper motor (8); at least two stepper motor
driving relays (7), a switch box having an engine control dial (1), an
auto idle switch (2), a mode selection switch (3), the ECS being
operable under mode selection function and auto-idle function to
economize the fuel consumption, the method comprising the steps of :-
- sensing the pilot pressure during the machine operation by
disposing said plural sensors in the ports of said control valve;
- a main controller of the machine receiving signals relating to the
operating load of the machine;
- regulating the engine rpm based on said operating load of the
machine.

wherein the engine rpm is regulated by controlling fuel injection to the
engine through the stepper motor