# US 4,395,990 A · Fuel injection pump > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,395,990 A - Document ID: US4395990A - Status: Granted - Kind: A - Application number: 06/260,475 - Filed: 1981-05-04 - Granted: 1983-08-02 - Earliest claimed: 1976-10-23 - Assignees: Robert Bosch GmbH - Inventors: Gerald Hofer; Karl Konrath; Franz Eheim; Otmar Weiss; Edgar Schmitt; Werner Faupel; Edgar Gotz - Web page: https://patentgrep.com/patent/US4395990A ## CPC - F02M 41/128: {Varying injection timing by angular adjustment of the face-cam or the rollers support} - F02D 1/183: {hydraulic} - F02B 3/06: with compression ignition (compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02) - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) ## Abstract A fuel injection pump for Diesel engines in which a rotating and reciprocating piston pressurizes and distributes fuel to individual pressure lines leading to the injection valves of the engine. In order to change the timing of injection with respect to the engine cycle, there is provided a mechanism to change the relative angle between the pressurizing piston and its drive means, which runs in synchronism with the engine. The mechanism operates hydraulically and is affected by the fuel pressure in the sump of the injection pump. There is also provided a hydraulic control valve mechanism which permits varying amounts of fuel to flow back from the sump to the low pressure side of the fuel delivery pump, thereby changing the injection timing. A primary control valve adjusts the sump pressure on the basis of engine speed while a secondary control valve adjusts the sump pressure on the basis of engine temperature in order to adapt the timing of fuel injection to engine starting and engine warm-up. Various embodiments are presented. ## Claims ### Claim 1 In a fuel injection pump for an internal combustion engine having: a fuel sump; a housing, a working cylinder defined within the housing which receives fuel from the fuel sump; a pump piston mounted for movement within the working cylinder; drive means for effecting the movement of the pump piston; adjusting means including an adjustable piston and restoring force means, said adjustable piston being displaceable against the force of the restoring force means, for adjusting the drive means and thus the movement of the pump piston; a fuel passage leading to the fuel sump; fuel supply means for supplying fuel through the fuel passage to the fuel sump; and pressure control means for controlling the pressure of the fuel supplied by the fuel supply means through the fuel passage, at least in accordance with engine speed and by means of controlling the flow of a partial quantity of fuel back to the fuel supply means, the pressure control means including a movable member and means exerting a closing force against the movable member, the movable member controlling the fuel flow back to fuel supply means and being subjected to the fuel pressure in the passage, which is exerted against the movable member in opposition to the closing force, the improvement comprising: a control valve including a movable member, means defining a bypass fuel passage from said fuel sump through said control valve to said fuel supply means, and means exerting a closing force against the movable member, wherein the movable member controls the bypass fuel passage and is subjected to the fuel pressure in the bypass fuel passage which is exerted against the movable member in the direction of the closing force; and control valve actuating means including a heatable thermostat exposed to engine temperature operative at least during engine starting and until engine warm-up, said thermostat having a movable member engageable with the movable member of the control valve for actuating the control valve for controlling a partial quantity of fuel through the bypass fuel passage back to the fuel supply means: wherein the pressure control means, the control valve and the control valve actuating means effect a relative reduction of a total partial quantity of fuel back to the fuel supply means and a corresponding relative increase in the fuel supply pressure in the fuel sump. ### Claim 2 (depends on 1) The fuel injection pump as defined in claim 1, wherein the control valve movable member is actuated by said control valve actuating means to establish communication from the fuel passage to the fuel supply means. ### Claim 3 (depends on 2) The fuel injection pump as defined in claim 2, wherein the means exerting a closing force against the control valve movable member comprises a spring. ### Claim 4 (depends on 1) The fuel injection pump as defined in claim 1, wherein the thermostat is adapted to be heatable by engine coolant. ### Claim 5 (depends on 1) The fuel injection pump as defined in claim 1, wherein the thermostat includes a working element of expansible material. ### Claim 6 (depends on 1) The fuel injection pump as defined in claim 1, wherein the thermostat includes a side remote from the control valve, and wherein the control valve actuating means further comprises a spring mounted on the side of the thermostat remote from the control valve, said spring serving to prevent excessive displacement of said control valve by the thermostat.