Fine and accurate control

DENSO has been producing injection pumps for diesel engines since 1957. Excellent fuel economy and power underlie the

popularity of diesel engines in trucks, busses, agricultural and construction vehicles around the world.

In Europe, where public concern about fuel economy and global warming is especially strong, diesel-powered passenger cars are common.

In the interests of protecting the natural environment, in recent years greater demands have come to be placed on cleaner exhaust gas emissions. Improvements were also required in the performance of injection pumps. Furthermore the advent of high-performance engines demanded various types of fuel injection controls that are difficult to achieve with mechanical pumps.

To address these issues, DENSO has adopted the ECD (Electronically Controlled Diesel) injection pumps. Electronically-controlled injection pumps use a microcomputer to control the fuel injection timing according to the running conditions of the engine. Unlike conventional mechanical control, these pumps control fuel injection and injection timing electronically. The result: fine and accurate control.

Mechanically controlled pumps

Mechanically controlled injections pumps are divided in two categories: the in-line type and the distributor type. In-line fuel injection pump The In-line fuel injection pump has the same number of fuel pressure mechanisms (elements) as engine cylinders. This type of pump (including the governor, timer and the feed pump on the pump s body) is mainly used for medium and large trucks and construction machinery. The pump body is equipped with fuel pressure/feed mechanisms (elements) and injection quantity control mechanisms. Furthermore there is a camshaft to drive these mechanisms. The elements in the pump body feed fuel to each engine cylinder according to the injection order.

Distributor injection pump

The Distributor injection pump has only one fuel pressure mechanism, irrespective of the number of engine cylinders. Instead, it has a distributor designed to distribute the pressurized fuel to each cylinder according to the injection order. All the components, including the governor, timer and feed pump, are built into the pump housing. It is a small and light type of pump that can operate at high speeds which is why it is widely used for small engines

Electronically controlled pumps

There are two types of electronically controlled fuel injection pumps available: the distributor type and the common rail type.

The injection method is completely different from conven-tional fuel injection pumps such as in-line pump types.

Distributor (rotary) fuel injection pump

The electronic control system of the distributor type pump consists of various sensors, an ECU (computer) and an actuator. 

The system detects the running condition of the engine, using the sensors while the ECU controls both fuel injection

quantity and injection timing. The actua-tor controls the injection quantity and the injection timing according to the signal

sent from the ECU. This ECU calculates the optimum injection quantity and injection timing for the current running condition

of the engine using signals from the sensors.

Common rail fuel injection pump (supply pump)

The common rail type pump is completely different from conventional fuel injection pumps. This type has been developed to meet strict exhaust gas regulations in the 21st century. This system consists of a supply pump, common rail, electronically controlled injectors, various sensors to detect the running condition of the engine and a computer (ECU) to control these devices.

The supply pump is driven by the engine and produces high-pressure fuel. An injector is mounted on each cylinder of the engine and the high-pressure fuel from the supply pump is distributed to each injector by the common rail