Zexel Gmbh

Takashi Ohishi

Hiroshi Ishiwata

Nobuhiro Kitahara

Hisashi Nakamura

Kenichi Kubo

Atsushi Ueda

Tohru Yokota

Masahiko Shinagawa

Naotake Ohi

Satoshi Yajima

Toshihumi Noda

Hosokawa Hitoshi

Mitsuhiro Fujita

An objective of the present invention is to provide a fuel injection pump wherewith, in addition to main injection, pre-injection is made possible in the vicinity of top dead center in the exhaust stroke, and wherewith, by regulating the pre-stroke, defined as the stroke from bottom dead center of a plunger 2 to the commencement of fuel line pressurization, it is possible to freely control both the pre-injection volume and the pre-injection timing relative to the main injection. Attention having been given to the combining of a pre-stroke varying mechanism together with a two-stage injection mechanism, the present invention is a fuel injection pump that is made so that a pre-stroke is regulated by changing the relative positions, in the axial direction, of a plunger 2 that sends fuel under pressure and a control sleeve 3 that fits around the outside of the plunger 2 so as to slide freely thereon. The cam 4 that drives the plunger 2 comprises a main cam nose 20 for main injection use and a pre cam nose 21 for pre-injection use.

Fuel injection pump

A pilot injection controller and a method of controlling pilot injection quantity enable the quantity of fuel pilot-injected fuel by an internal combustion engine fuel injection system of the type in which the fuel delivery stroke for pilot injection is fixed to be maintained substantially constant irrespective of engine speed by controlling prestroke such that the utilized portion of a cam is shifted to a lower delivery velocity region thereof with increasing engine speed, the principle involved being that the quantity of fuel pilot-injected by a fuel injection system is proportional to the actual plunger delivery velocity and the fact that since the actual delivery velocity is proportional to the product of the cam velocity constant and the cam rotational speed the actual delivery velocity can be maintained substantially constant by increasing the cam velocity constant in the low speed region and decreasing the cam velocity constant in the high speed region.

Pilot injection controller in fuel injection system and method of

A pilot injection control system for an internal combustion engine comprises a plurality of fuel injection nozzles, the valve-opening pressure of one of which (the reference nozzle) is set slightly higher than that of the other nozzles, means for detecting the pilot injection of the reference nozzle, and means for feedback controlling the pilot injection quantity of the reference nozzle based on the detected pilot injection. The system is able to effectively control the pilot injection of all nozzles by actually controlling the pilot injection of only one nozzle and can therefore be implemented at low cost.

Pilot injection control system

A solenoid valve unit is provided in the middle of fuel supply path that leads to a compression space in an injection pump main body, and the fuel injection quantity is adjusted through the open and close control of the solenoid valve unit. In this fuel injection system, the plug valve is moved until it is seated on the valve seat during the preliminary injection that is performed prior to the main injection. An arrangement for leaking the fuel from within the compression space is provided in the injection pump main body and the time period during which the fuel in the compression space is leaked via the arrangement for leaking and the time period during which the fuel supply path is restricted with the plug valve being seated on the valve seat are combined to stabilize the movement of the plug valve. Consequently, an optimal small quantity is achieved for the preliminary injection that is nearly constant regardless of the rate of rotation of the engine. Also, if a drive pulse that closes the fuel supply path over the period during which the fuel is leaked is supplied to the solenoid valve unit, the solenoid valve unit needs to be operated only once and stable injection characteristics are achieved from the pilot injection through the main injection.

Fuel injection system

A fuel-injection device includes a solenoid valve which adjusts a fuel-injection level of a fuel-injection pump by adjusting its throttling for the fuel-injection passage to supply the fuel to a compressor. A driving pulse to drive the solenoid valve is formed taking various factors into consideration. For example, the driving pulse is composed of a segment having a large duty ratio and a segment having a small duty ratio in order to secure a responsiveness of the solenoid valve. The driving pulse is formed on the basis of a change in electrical voltage to drive the solenoid valve, varying levels of voltage drop in a wiring harness installed for every cylinder, and of varying levels of responsiveness unique with fuel-injection pumps.

Fuel-injection device

A fuel-injection device adjusts a fuel-injection level with a solenoid valve disposed in a fuel-supply passage which supplies the fuel to a compressor. A pulse width of a drive pulse to actuate the solenoid valve, which is determined by the sum of a time lag in the valve's closing caused by the motion of the valve member of the solenoid valve and of the time length at which the valve is to remain closed, is made shorter than the time lag in the valve's closing when the engine load is low. Current supplied to the solenoid is thus cut off immediately before the solenoid valve is completely closed, and a preflow caused by a rise in injection-pressure is reduced.

A method for varying the flow rate of fuel in a distributor-type electronic control fuel-injection pump. A single solenoid valve is used to control the timing of initiating and terminating fuel delivery. A cam is operated under four different modes, a low idle or a low speed/low load zone, a middle load zone, a high load zone, and a governing or high idle zone in that order as the cam is rotated. At the governing or high idle zone, the solenoid valve is closed before the cam is lifted and is opened to control fuel delivery when it is terminated.

Growing community of inventors

Higashimatsuyama, Japan

Takashi Ohishi