The Bosch VE pump is a single-plunger distributor pump. Unlike inline pumps that have a separate pumping element for each cylinder, the VE pump uses a single pumping element to serve all cylinders.

Here is the breakdown of its structure and why it is advantageous:

1. Key Structural Characteristics

A. The Drive Shaft and Vane Pump

• Structure: The pump is driven by the engine. Inside, the driveshaft rotates a vane-type transfer pump (also called a feed pump).

• Function: This vane pump draws fuel from the tank and pressurizes it inside the pump housing (typically 3-7 bar). This "internal pressure" is a key feature of the VE design.

B. The Hydraulic Head and Distributor Rotor

• Structure: This is the heart of the pump. It consists of a stationary hydraulic head and a rotating distributor rotor.

• Function: As the rotor spins, it aligns with ports in the hydraulic head. It performs two actions:

1. Filling: It aligns with the inlet port to allow fuel into the high-pressure chamber.

2. Distributing: It aligns with the outlet port corresponding to the correct cylinder (1-3-4-2) to send the high-pressure fuel out.

C. The Single Plunger and Cam Plate

• Structure: Inside the rotor, there is a single plunger pair (two plungers facing each other). Behind them is a stationary cam plate with lobes (one for each cylinder).

• Function: As the rotor spins, rollers on the plate ride over the cam lobes. This forces the plungers together, generating the high pressure (up to 700-900 bar) needed for injection.

D. Solenoid Valve (Stop Valve)

• Structure: An electrical solenoid mounted on top of the pump head.

• Function: When you turn the ignition on, it opens to allow fuel into the high-pressure circuit. When you turn the ignition off, it cuts the fuel supply, shutting down the engine. (This replaced the old mechanical cable stop on older pumps).

E. Mechanical Governor and Advance Device

• Structure: A mechanical flyweight governor on the drive shaft and a hydraulic timing advance piston inside the pump housing.

• Function:

• Governor: Adjusts the fuel volume based on engine speed and load (throttle position).

• Advance: Uses the internal vane pump pressure to rotate the cam plate slightly, advancing the injection timing as RPM increases for better efficiency.

2. Advantages of this Design (Why Mitsubishi chose it)

A. Compact and Lightweight

• Advantage: Because it uses one pumping element instead of four, the VE pump is significantly smaller and lighter than the inline pumps it replaced (like the Bosch A or P-type). This allows manufacturers like Mitsubishi to design smaller, more compact engine bays for their Canter trucks.

B. Built-in Self-Lubrication

• Advantage: The pump is lubricated and cooled by the diesel fuel flowing through it. There is no separate oil sump. This simplifies maintenance (you don't have to change pump oil) and ensures the pump is constantly cooled by fresh fuel.

C. Integrated Timing Advance

• Advantage: The internal hydraulic advance mechanism automatically adjusts the injection timing as the engine RPM increases. This provides:

• Better Fuel Economy: Optimal timing ensures complete combustion.

• Reduced Smoke: Less unburnt fuel at higher speeds.

• Smoother Operation: Reduces engine knock at low RPM.

D. Reliability and Tolerance

• Advantage: The VE pump is renowned for being robust. For a Mitsubishi Canter used in commercial applications (where maintenance isn't always perfect), this pump tolerates minor fuel contamination better than modern high-pressure common rail systems. It also doesn't require a complex electronic control unit (ECU) to manage timing, making it easier for mechanics in remote areas to diagnose and repair.

E. Simplicity of Calibration

• Advantage: While it looks complex, the fact that all cylinders are fed by a single plunger means that the fuel delivery is inherently equal to all cylinders. In an inline pump, if one cylinder element wears out, that cylinder runs rough. In a VE pump, if the plunger wears, all cylinders are affected equally, making diagnosis easier.

  Diesel pump supplier:
  

  Rsolid is a professional diesel injector manufacturer that relies on the precision manufacturing capabilities of its own factories to provide high-quality solutions for the global commercial vehicle, construction machinery, marine, and agricultural diesel engine markets. Rsolid's business model typically includes maintaining a diverse and comprehensive OEM and high-end aftermarket parts inventory, and providing cross compatibility options to meet the needs of various applications and global customers, from individual workshops to large fleet operators. If you are looking for diesel injectors or OEM engine injectors, please feel free to contact us at any time.