RU45479U1 - CAM MECHANISM FOR DRIVING THE DIESEL ENGINE HIGH PRESSURE FUEL PUMP PLUNG DRIVE - Google Patents

Abstract

The utility model relates to a diesel fuel supply system and can be used to design a plunger drive for a diesel engine high pressure fuel pump pump. The cam mechanism of the plunger drive of the diesel engine high pressure fuel pump contains a rotating tangential cam, an axisymmetric guide and a roller with a pusher interacting with the tangential cam. The roller is mounted with the possibility of reciprocating movement together with the pusher along the guide. The guide and the roller with the pusher are located with an offset of their axis relative to the axis of rotation of the tangential cam in the direction of the common interaction surface of the tangential cam and the roller. The amount of displacement is selected for each specific design. The claimed utility model allows to increase the efficiency of the mechanism, improve the working conditions of the mechanism, reduce the power spent on the drive and loads by reducing the pressure angle.

Description

The invention relates to a fuel supply system and can be used in the development of a cam mechanism for driving a plunger of a high pressure fuel pump (TNVD) of a diesel engine.

Known cam drive mechanism of the plunger of the injection pump of a diesel engine containing an axisymmetric rotating cam with a convex profile, a guide and a roller with a pusher, interacting with the cam and installed with the possibility of reciprocating movement together with the pusher along the guide [B. Faynleib. Fuel equipment of automotive diesel engines: Reference book. - 2nd ed., Revised. and add. - L .: Mechanical engineering. Leningra. Department, - 1990. - p.126].

Closest to the proposed utility model adopted as a prototype is the cam mechanism of the plunger drive of the injection pump of a diesel engine containing an axisymmetric rotating tangential cam, a guide and a roller with a pusher interacting with the tangential cam and mounted with the possibility of reciprocating movement together with the pusher along the guide. The tangential profile of the cam most fully meets the design and technological requirements for multi-plunger injection pumps, namely it provides higher fuel injection pressures than the convex profile and is simpler to manufacture [B. Fainleib Fuel equipment of automotive diesel engines: Reference book. - 2nd ed., Revised. and add. - L .: Mechanical engineering. Leningra. Department, - 1990. - p.130].

Common disadvantages of the described cam mechanisms are low efficiency, reliability and durability due to

extremely high pressure angle γ _max , since with an increase in γ _max the efficiency of the mechanism decreases, its working conditions deteriorate, up to jamming, the power expended on the drive increases, the loads in the mechanism increase; the limit value of γ _max is a value equal to 37-40 °.

The proposed utility model solves the problem of increasing the efficiency, reliability and durability of the cam mechanism.

To achieve the specified technical result in the cam mechanism of the plunger drive of the injection pump of a diesel engine containing a rotating tangential cam, an axisymmetric guide and a roller with a pusher interacting with a tangential cam and installed with the possibility of reciprocating movement together with the pusher along the guide, the guide and the roller with the pusher are located with the displacement of their axis relative to the axis of rotation of the tangential cam in the direction of the common interaction surface angentsialnogo cam and roller.

Improving the efficiency, reliability and durability of the cam mechanism is achieved by reducing the pressure angle γ _max .

The angle γ _max , being a geometric parameter, depends on the initial structural dimensions of the mechanism. For the proposed utility model, the following expression was obtained for this dependence:

where R ₀ is the radius of the initial circumference of the cam profile;

r ₀ is the radius of the roller;

R _g is the radius of the cam profile head;

r is the radius of curvature of the cam profile;

Δ is the displacement of the axis of the guide and the roller with the pusher relative to the axis of rotation of the cam.

The specified offset changes the geometry of the cam mechanism so that the angle γ _max decreases. To prove this, we give a comparison using the expression for γ _{max of the} proposed cam mechanism and the cam mechanism selected as a prototype.

For a cam gear selected as a prototype:

R ₀ = 16 mm, r ₀ = 10 mm, R _g = 28 mm, r = 3 mm, Δ = 0;

For the proposed cam mechanism:

R ₀ = 16 mm, r ₀ = 10 mm, R _g = 28 mm, r = 3 mm, Δ = 4 mm;

The proposed cam drive mechanism of the plunger of the injection pump of a diesel engine is illustrated in the drawing, which shows a diagram of this mechanism.

In addition, in the drawing, the arrow indicates the direction of rotation of the cam.

The cam drive mechanism of the plunger of the injection pump of the diesel engine contains a rotating tangential cam 1, an axisymmetric guide 2 and a roller 3 with a pusher 4, interacting with a tangential cam 1. The roller 3 is mounted with the possibility of reciprocating movement together with the pusher 4 along the guide 2. Guide 2 and the roller 3 with a pusher 4 are located with an offset 5 of their axis relative to the axis of rotation of the tangential cam 1 in the direction of the common surface 6 of the interaction of the tangential cam 1 and the roller 3. Angle 7, the pressure of the ears is formed by a line passing through the common surface 6 of the interaction of the tangential cam 1 and the roller 3 and the center of the roller, and the common axis of symmetry of the guide 2 and the roller 3 with the pusher 4.

An offset value of 5 is selected for each particular cam design.

The operation of the cam mechanism is as follows

The tangential cam 1 rotates around its axis of rotation. The roller 3 and the pusher 4 rest on the cam 1 and the guide 2. The cam 1 runs on the roller 3, while the roller 3 rotates around its axis of rotation, and the pusher 4 with the roller 3 moves reciprocally along the guide 2, the axis of which is offset 5 relative to the axis of rotation of cam 1. A plunger (not shown in the diagram) is supported on the pusher 4, which moves with it and pumps fuel into the cylinder of the diesel engine.

Thus, in the proposed cam mechanism with the same sizes as the prototype, the cam and roller have an increase in efficiency, an improvement in the working conditions of the mechanism, a decrease in the power spent on the injection pump drive, and a decrease in the loads in the mechanism.

Claims (1)

A cam mechanism for driving a plunger of a diesel engine high pressure fuel pump, comprising a rotating tangential cam, an axisymmetric guide and a roller with a pusher interacting with a tangential cam and mounted with the possibility of reciprocating movement together with the pusher along the guide, characterized in that the guide and the roller with the pusher are located with an offset of their axis relative to the axis of rotation of the tangential cam in the direction of the common interaction surface t angular cam and roller.