Selection of cam mechanisms for driving the plunger of high-pressure pump of diesel engines using Mathcad program

Abstract

The purpose of the article is to select the cam profile (with equal design parameters) for driving the plunger of a high-pressure pump that provides the maximum speed and permissible acceleration of the pusher. A method of selecting a cam profile by analyzing combined graphs of changes in the path, speed, and acceleration of a cam pusher of various profiles using the Mathcad program is proposed. Calculations have been performed and combined graphs of changes in the path, speed, and acceleration of the cam pusher with tangential, convex, and concave profiles have been constructed. A comparative analysis of the combined graphs showed that the maximum speed of the cam pusher with a concave profile is 1,5 times greater than for cams with a tangential or convex profile. A cam with a concave profile is recommended for driving pump plungers of low-speed marine diesel engines (up to 250 min–1). To create ultra–high pressures (more than 120 MPa), the fuel supply system must be batterytype with a drive of small diameter plungers (4–6 mm) from an eccentric shaft with a special-shaped washer and electronically controlled injectors.

Keywords

• cam mechanisms
• cam profile
• calculation
• mathcad program
• graphs of path
• speed
• acceleration
• cam profile selection