How to control EFI diesel engine?

C A N bus technology is widely used to control the speed of excavator EFI diesel engine, that is, throttle hard characteristic control. The throttle control methods of EFI diesel engine include linear throttle, on-off throttle, frequency throttle, remote throttle and J 1939 multi-channel throttle. This paper introduces J 1939 multi-way throttle valve.

1. Structure composition

J 1939 multi-channel throttle control system mainly consists of main pump 1, diesel engine 2, diesel engine controller 3, electronic monitor 4, throttle knob 5, main controller 6, front pump pressure sensor 7, rear pump pressure sensor 8, pilot pressure sensor 9 and main pump electric proportional reducing valve 10, as shown in figure 1.

Turn left | turn right

The main pump 1 is connected with the diesel engine 2, and the main controller 6 is connected with the diesel engine controller 3 and the electronic monitor 4 through the CAN bus. The input port 1 of the main controller 6 is connected with the throttle knob 5, and the input ports 2, 3 and 4 of the main controller 6 are respectively connected with the front pump pressure sensor 7, the rear pump pressure sensor 8 and the pilot pressure sensor 9. The output port of that main control 6 is connected with the electric proportional reduce valve 10 of the main pump.

2. Working principle

J 1939 multi-way throttle uses J 1939 data communication information (PGN 6 1443 accelerator pedal position) to set the throttle percentage, and the throttle does not need to be connected with diesel engine ECU through wires. The multi-way throttle valve uses J 1939 data communication interface to send or receive input and output control instructions instead of a single hard wire.

(1) speed control

When the excavator is working, the driver turns the throttle knob 5, and the main controller 6 collects the position signal of the throttle knob 5. After calculation, the corresponding instructions such as throttle percentage, speed adjustment and torque curve are transmitted to diesel engine ECU 3 through CAN bus, so as to control the speed of diesel engine. The main controller 6 compares the target speed of the diesel engine with the actual speed, and sends a signal to control the absorption of diesel engine power by the main pump 1.

When the diesel engine speed is lower than the target speed, the main controller 6 sends a control signal to reduce the power absorbed by the main pump by adjusting the electro-hydraulic proportional pressure reducing valve 1 0, thereby reducing the diesel engine load and increasing the diesel engine speed.

When the diesel engine speed is higher than the target speed, the power absorbed by the main pump increases, the diesel engine load increases and the diesel engine speed decreases. Only when the power matching between diesel engine and main pump reaches the best can we achieve the purpose of energy saving, high efficiency and low noise.

(2) Power supply mode

According to different working conditions, the driver can choose different power modes to work through the electronic monitor. According to different power modes, the main controller selects different diesel engine speed regulation rates and different torque percentages, as shown in Figure 2.

Turn left | turn right

In the heavy load mode (H mode), the minimum speed regulation (maximum slope and minimum speed regulation range) can be adopted, that is, the speed regulation ratio is 2 and the torque is 100%, so that the main pump can make maximum use of the output power of the diesel engine and exert the highest working efficiency.

In the economic mode (S mode), the intermediate speed regulation (variable torque curve 1) is adopted, that is, speed regulation 3, and the torque is slightly lower than 100%, which can enhance the power matching between diesel engine 2 and main pump 1 and improve fuel economy.

In the light load mode (L mode), the maximum speed regulation (that is, variable torque curve 2), that is, normal speed regulation, can reduce the torque by more than 100% at most to improve the micro-operation performance of the excavator.

The multi-speed throttle control method has obvious energy-saving effect and high working efficiency. It has been applied to excavators equipped with EFI diesel engines and achieved good results.