Injection pumps for diesel engines
Optimal performance and injection precision
How a Diesel Injection Pump Works The diesel injection pump is the heart of the engine's fuel system, responsible for delivering fuel with millimetric precision. Its operation is based on three fundamental processes: metering, pressurization, and timing. Initial supply: Diesel is drawn from the tank by an auxiliary feed pump. This flow reaches the injection pump, where it is filtered to remove impurities that could affect the system. Fuel pressurization: Inside the pump, small pistons driven by the camshaft compress the fuel to very high pressures (up to 2000 bar), necessary to ensure optimal atomization in the combustion chamber. Metering and timing: Each pump pulse is synchronized with the crankshaft position, ensuring that the fuel reaches the cylinder at the exact moment. The amount injected varies according to engine demand and is regulated by a mechanical or electronic system. Distribution to the injectors: In linear pumps, each cylinder has its own piston. In rotary pumps, a single piston distributes the diesel through internal valves that direct the flow to each injector. In-chamber injection: Once the fuel is received, the injectors spray it into very fine droplets inside the cylinder, initiating the combustion process that generates the engine's power. 1. Linear (multiple piston) pump Technical characteristics: Each cylinder has a dedicated piston. Synchronized operation via camshaft. High injection precision per cylinder. Advantages: Very precise at high pressures. Ideal for industrial or high-power engines. Disadvantages: Bulky and more complex to adjust. Specialized maintenance required. 2. Rotary (distribution) pump Technical characteristics: A single piston distributes the fuel to all cylinders. Uses a rotating rotor for dosing. Mechanical or electronic flow control. Advantages: More compact and lighter than the linear pump. Easy installation and maintenance. Disadvantages: Lower precision under high demands. Sensitive to internal wear. 3. Unit Injector System Technical characteristics: Each injector incorporates its own mini pump. Direct mechanical drive from the camshaft. High pressure performance and response time. Advantages: Optimal fuel atomization. Precise injection per cylinder. Disadvantages: Greater technical complexity. Requires individual calibration per injector. 4. Common Rail (Modern System) Technical characteristics: Centralized high-pressure pump. Accumulator (common rail) that feeds all injectors. Electronic injection control by a control unit (ECU). Advantages: Multiple injection per cycle. Lower noise, greater efficiency, and lower pollutant emissions. Disadvantages: Complex system with high electronic dependence. High repair costs. Types of Common Rail Pumps Bosch CP1: First generation, 3 pistons, pressure up to 1350 bar. CP3: More robust, up to 1800 bar, used in heavy vehicles. CP4: Compact and efficient, but sensitive to fuel quality. Denso HP2: Double pumping mechanism, pressure up to 145 MPa. HP3: Compact, 2 cylinders, pressure up to 200 MPa. HP4: 3 cylinders, higher flow, used in medium trucks. Delphi Similar design to Bosch, but with a different internal structure. Uses SCV (flow control valve) regulators. Common in European vehicles such as Renault and Peugeot Siemens / Continental Self-priming, with two pressure stages. Evolution towards VDO pumps, affected by the "Dieselgate" case. They usually present flow problems if not properly maintained Key components Flow regulator: Controls the entry of low-pressure fuel. Pressure regulator: Maintains the pressure in the common rail. Temperature sensor: Adjusts the injection according to the fuel temperature.
