Question: What is the function of the control circuit of the electric gasoline pump? Don't be afraid to answer.

Mechanical control relay circuit of gasoline pump

1. 1 Toyota used a fender flowmeter with an oil pump switch in it. As shown in the figure, the gasoline pump relay has built-in double coils, which belongs to the intermediate relay, that is, when there is current in the electromagnetic coil, the electromagnetic contact switch is closed.

1. 1. 1 control principle:

1. 1. 1. 1

When starting, the ST end of the ignition switch supplies power to the L2 coil of the gasoline pump relay, so that the normally open contact of the relay is closed, the working circuit of the gasoline pump forms a loop, and the gasoline pump starts pumping oil.

1. 1. 1.2

It works normally. If the engine starts smoothly, the oil pump switch in the fender flowmeter is turned off by the intake airflow, and the gasoline pump relay continues to pull in, and the gasoline pump is turned on until the engine is turned off.

The second engine computer controls the negative pole of the gasoline pump relay.

2. 1 ECU control directly controls the negative pole of the gasoline pump relay.

This is the most common one. ECU directly controls the negative pole of gasoline pump relay to form a loop, as shown in the figure. ECU decides whether to control the gasoline pump according to the signals such as start-up and CKP, and provides grounding for the gasoline pump relay to form a loop to make the gasoline pump work when the conditions are met.

2.2 Loading inertia switch

2.2. 1 inertia switch function

The car of Shenlong Fukang is equipped with a fuel inertia switch. The inertia switch is located on the right front shock absorber and marked with a red soft cap. As can be seen from the circuit diagram, the inertia switch is connected in series in the relay control loop. When a collision or impact occurs, the normally closed contact in the inertia switch is disconnected, interrupting the relay control loop of the gasoline pump, and the gasoline pump stops working. If the engine oil inlet pipe breaks or breaks during collision or impact. Installing fuel inertia switch can reduce the possibility of car fire and increase the chance of driver's escape.

Principle of inertial switch

The inertia switch has three terminals, with a normally open contact and a normally closed contact inside. Normally closed contacts are connected in series in the control loop of the oil pump relay. When the inertia switch works, the closed contact often becomes a "normally open contact", thus interrupting the control loop of the oil pump. Normally open contacts become "normally closed contacts". China Zunchi made full use of this and sent this signal to BCM. After BCM detects that the inertia switch is working, BCM controls to open the central lock and turn on the double flashing lights to inform other vehicles that there is a fault.

Three computers control the positive pole of gasoline pump relay.

3. 1 The engine computer directly controls the anode of the gasoline pump relay.

There are many engine control computers that make the gasoline pump work by controlling the relay of the gasoline pump to form a loop. However, there are also other automobile manufacturers who use the engine control computer to control the positive pole of the gasoline pump relay to make the gasoline pump work. The circuit diagram of Buick Regal is shown in the figure. Regal uses this control method to control the gasoline pump, which can avoid the short circuit of the relay control circuit of the gasoline pump in the event of a traffic accident and the possibility that the gasoline pump is out of control and causes a fire. Regal has "early" and "late" fuel supply modes to ensure that the fuel system has enough oil pressure and is easy to start. When the ignition switch is turned from LOCK to OFF. PCM controls the gasoline pump to work for 2 seconds. This way of supplying oil in advance can quickly establish oil pressure, so that there is enough oil pressure when starting. When the ignition switch is turned off, PCM controls the gasoline pump to continue running for about 3 seconds. This delayed oil supply ensures that the fuel system has enough oil pressure when it is started next time.

3.2 Auxiliary control mode of oil pressure switch

Chevrolet Lumina is equipped with a 3.3LV6 engine, and the gasoline pump relay of the car is installed behind the right headlight, which also belongs to the relay forward control mode. It has dual safety control, that is, the engine control computer and the oil pressure switch are simultaneously controlled. As shown in the figure, the main function of the oil pressure switch is to reduce the load of the gasoline pump relay and increase the service life of the gasoline pump relay. Secondly, if there is a problem with the relay or control loop of the gasoline pump, the engine will not be affected by the oil pressure switch. But only when the oil pressure switch works, the car will not stop after the next point, because the oil pressure is insufficient and the gasoline pump does not work.

Four control modes of oil pump-free relay

4. 1 computer control of independent oil pump

The gasoline pump control of Lexus IS300 is controlled by the quantitative voltage output from the oil pump ECU. The ECU of the oil pump is installed under the right C-pillar, and the power performance of the engine is not high at medium and low speeds, mainly considering fuel economy. The engine ECU outputs 0 volts to the oil pump ECU through the fibrechannel, and the oil pump ECU outputs about 9 volts of direct current to directly control the gasoline pump to run at low speed, which can prolong the service life of the oil pump. Engine ECU judges whether it is necessary to increase power according to the comprehensive processing of CKP, TPS, VSS and other signals. The engine ECU outputs 5 volts, and after the oil pump ECU receives it through the fibrechannel, the oil pump ECU outputs the power supply voltage, which makes the oil pump run at high speed and ensures the strong power of the engine.

4.2 Pulse (PWM) control

The new BMW 750LI and E65 adopt various communication modes. The gasoline pump is directly controlled by SBSR (right B-pillar satellite sensor), and the gasoline pump control chart. The control flow is that DME (Engine Computer) sends the signals needed for fuel quantity, and the signals are sent by PT.

CAN is transmitted to ZGM (body computer) and transmitted to gateway SIM through Bytefilht, and then the SIM transmits the fuel demand signal to SBSR, which is interpreted by the designated decoding program, and then the speed of gasoline pump is controlled by PWM. SBSR constantly detects and corrects the working state of the oil pump. If the transmission signal is lost or the bus fails, SBSR can't determine the fuel signal required by DME. SBSR takes fault protection measures, that is, turn on 15 power supply, and SBSR controls the gasoline pump to run at high speed to provide enough fuel to keep the engine running. SBSR has fault detection function, and DTC is recorded in SBSR, which can be read by diagnostic instrument.