Mechanical distributor injection pump having cold-start acceleration

• US 6,748,930 B2
• Filed: 11/21/2002
• Issued: 06/15/2004
• Est. Priority Date: 11/21/2001
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Banham, David, Freudl, Volker, Bofinger, Guenter
• Primary Examiner(s): Moulis, Thomas N.
• Application Number:
  US10/301,057
• Publication Number:
  US 20030121504A1
• Time in Patent Office: 572 Days
• Field of Search: 123/502, 123/179.16, 123/179.17
• US Class Current: 123/502
• CPC Class Codes: F02D 1/183 hydraulic
• CPC Class Codes: F02D 2001/186 using a pressure-actuated piston for adjustment of a stationary cam or roller support
• CPC Class Codes: F02M 41/128 Varying injection timing by angular adjustment of the face-cam or the rollers support
• CPC Class Codes: F02M 41/1416 Devices specially adapted for angular adjustment of annular cam

Abstract

A high-pressure pump for supplying internal combustion engines with fuel includes a housing, on which a timing unit for displacing the point of injection is accommodated. The timing unit includes an injection timing piston having inlet bores, and a regulating slide, whose face facing a cold-start accelerator piston has a prestress force applied to it, is movably accommodated in the injection timing piston. A spring element, which is applied directly to the injection timing piston, as well as a spring assembly, which is independent of the spring element and accommodated on a carrier and act on the regulating slide, are positioned between the cold-start accelerator piston and the opposing face of the injection timing piston.

Claims

1. A timing unit for a high-pressure pump for supplying an internal combustion engine with fuel, the timing unit displacing a point of injection and being accommodated on a housing of the high-pressure pump, comprising:

a cold-start accelerator piston;

an injection timing piston having inlet bores;

a regulating slide movably accommodated in the injection timing piston, a face of the regulating slide facing the cold-start accelerator piston having an applied pre-stress force; and

a first spring element, and a separate spring assembly accommodated on a carrier, positioned between the cold-start accelerator piston and the face of the injection timing piston;

wherein the first spring element acts directly on a stop of the injection timing piston, and wherein the spring assembly acts on the regulating slide.

2. The timing unit as recited in claim 1, wherein the spring assembly includes a plurality of spring elements connected in series.

3. The timing unit as recited in claim 1, wherein the spring assembly includes a second spring element and a third spring element supported on a spring support ring, the spring support ring being movably accommodated on the carrier.

4. The timing unit as recited in claim 3, wherein the spring support ring includes a first side and a second side.

5. The timing unit as recited in claim 3, wherein the second spring element is accommodated between the cold-start accelerator piston and the spring support ring, and has a first spring stiffness.

6. The timing unit as recited in claim 3, wherein the third spring element is accommodated between the injection timing piston and the spring support ring, and has a second spring stiffness.

7. The timing unit as recited in claim 1, wherein the cold-start accelerator piston includes a plurality of stepped contact surfaces on an interior surface of the cold-start accelerator piston, the interior surface facing toward a cavity.

8. The timing unit as recited in claim 7, wherein a fourth spring element is accommodated between a first contact surface of the cold-start accelerator piston and an adapter plate, the adapter plate forming a stop ring for the injection timing piston.

9. The timing unit as recited in claim 7, wherein the first spring element acting directly on the stop of the injection timing piston presses against a second contact surface of the cold-start accelerator piston.

10. The timing unit as recited in claim 1, wherein the first spring element acting on the face of the injection timing piston presses a slotted disk against the face, a plurality of slotted legs of the slotted disk engaging a plurality of recesses provided, limiting an axial displacement path of the regulating slide.

11. The timing unit as recited in claim 6, wherein the third spring element of the spring assembly is accommodated between the spring support ring of the carrier and a support ring of the regulating slide.

12. The timing unit as recited in claim 1, wherein:

the regulating slide includes a channel, the channel extending through a support ring; and

when the regulating slide is pressed against a spring support ring, a cavity between the cold-start accelerator piston and the injection timing piston inside the timing unit is filled with fuel via a plurality of orifices provided on the spring support ring.