Internal-combustion engines – Charge forming device – With fuel pump
Reexamination Certificate
2000-12-26
2003-03-04
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Charge forming device
With fuel pump
C123S497000
Reexamination Certificate
active
06526947
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a high-pressure fuel pump control device and an in-cylinder injection engine control device, and particularly to a high-pressure fuel pump control device and an in-cylinder injection engine control device for controlling the operation of a high-pressure fuel pump for force-feeding a high pressure fuel to a common rail of a fuel injection valve.
The present vehicle needs to reduce exhaust gas substance such as carbon monoxide (CO), hydrocarbon (HC), nitrogen oxides (Nox), etc. contained in a vehicle exhaust gas from the view point of environment protection. The development of a direct injection engine (in-cylinder injection engine) has been done with the aim of reducing these gas substances. The in-cylinder injection engine directly injects a fuel from a fuel injection valve within a combustion chamber in a cylinder. Further, the fuel injected from the fuel injection valve is reduced in particle diameter to thereby promote or accelerate the combustion of the injected fuel and achieve a reduction in exhaust gas substance and an improvement in engine output, etc.
Reducing the particle diameter of the fuel injected from the fuel injection valve here needs means for bringing the fuel to high pressure. Various technologies for a high-pressure fuel pump for force-feeding a high pressure fuel to the fuel injection valve have been proposed (see, for example, Japanese Patent No. 2690734, Japanese Patent Laid-open No. Hei 10-153157, etc.)
The technology disclosed in Japanese Patent Application No. 2690734 relates to a variable delivery or discharge rate high-pressure pump for force-feeding a high pressure fuel to within a common rail (oil-storage path shared between cylinders) of a fuel injection device. The variable discharge rate high-pressure pump comprises a cylinder, a plunger driven by an engine built in the cylinder a pressure chamber formed by an upper end surface of the plunger and an inner peripheral surface of the cylinder, and an electromagnetic valve which faces the pressure chamber and is fixed to the cylinder. The variable discharge rate high-pressure pump is one in which the electromagnetic valve is energized to thereby close a low pressure path communicating with the pressure chamber, and the fuel placed in the pressure chamber increases in pressure owing to the elevation of the plunger so as to be force-fed to the common rail and hence the electromagnetic valve is opened or closed, whereby the amount of delivery or discharge of the fuel to the common rail is adjusted.
On the other hand, the technology disclosed in Japanese Patent Laid-open No. Hei 10-153157 relates to a variable discharge rate high-pressure pump for adjusting or controlling the amount of a fuel supplied to an engine by a fuel spill valve corresponding to an electromagnetic valve. The variable discharge rate high-pressure pump comprises a cylinder, a plunger built in the cylinder, and a pressure chamber formed by an upper end surface of the plunger and an inner peripheral surface of the cylinder. An inflow path for allowing the fuel to flow from a low pressure feed pump, a supply path for force-feeding a high-pressure fuel to a common rail, and a spill path communicating with a fuel spill valve for returning a fuel spilt from the pressure chamber to a fuel tank are connected to the pressure chamber. The fuel spill valve is opened or closed to thereby control the amount of delivery of the fuel to the common rail.
Meanwhile, the conventional technology disclosed in Japanese Patent Application No. 2690734 has a problem in that the electromagnetic valve which opens or closes the common rail, must be set to an always-opened type to control or suppress the occurrence of a vapor lock due to a substantial reduction in the pressure in the pressure chamber at a suction stroke of the plunger, and when the delivery of a fuel in maximum flow rate from the pressure chamber is made, a loss of a pressure-applying time due to an open delay in the electromagnetic valve occurs when the plunger shifts to a compression stroke, and the capability of fuel delivery is reduced, whereas when the delivery of a fuel in small flow rate from the pressure chamber is made, almost all time necessary for the compression stroke of the plunger is spent in maintaining the electromagnetic valve in an open state, whereby the electromagnetic valve must be opened or closed within a slight time lying between the intake stroke and compression stroke of the plunger.
In the conventional technology disclosed in Japanese Patent Laid-open No. Hei 10-153157, the inflow path and the spill path are provided separately, and the intake stroke of the plunger and the opening and closing of the spill valve are out of relation to the inflow of the fuel. Therefore, the above-described problem is solved. It is however necessary to provide valve sheets at two points with respect to the intake valve for the inflow path and the spill valve for the spill path in addition to a size increase in the variable discharge rate high-pressure pump due to the provision of the spill path. It is also necessary to improve the accuracy of processing of each valve sheet with a view toward preventing a reduction in delivery capability due to leakage of the fuel from the valve sheet. Therefore, the manufacturing cost increases and continuous energization must be carried out while the spill valve is being closed, thus causing inconvenience that power consumption will increase.
Further, any of the respective conventional technologies has a problem in that the operation of the electromagnetic valve must completely be synchronized with the reciprocating stroke of the plunger, and the high response of the electromagnetic valve and the high accuracy of a synchronizing signal are required, whereby a system necessary therefore becomes very expensive.
Here, the present applicant has studied with a view toward solving the above-described problems and proposed the inventions of variable discharge rate high-pressure pumps as the preceding applications in various ways. There is known, for example, a technology of a variable discharge rate high-pressure pump wherein when pressure on the downstream side (pressure chamber side) of an intake valve in an inflow path is equal to that on the upstream side (inflow path side) of the intake valve or greater than that due to a change in the volume of a pressure chamber by a plunger reciprocated according to the rotation of a cam, a push rod is provided in which a valve closing spring urged so as to close the intake valve is provided to close the intake valve and a valve opening spring urged so as to open the intake valve is provided, and the push rod is activated according to the energization or de-energization of a solenoid. Further, the above-described problems are solved owing to the separate provision of the intake valve and the electromagnetic valve, the separate provision of the intake valve and the push rod, and the configuration free of the provision of the valve sheets at the two points, etc.
Meanwhile, an operation timing chart from the start-up of an engine by the variable discharge rate high-pressure pump is shown in FIG.
22
. It is understood that the time between the determination of a crank angle signal after the beginning of cranking from the engine start-up and the determination of a plunger phase between the crank angle signal and a cam angle signal for driving a plunger no allows the output of a solenoid control signal, a first solenoid control signal is outputted based on a REF signal only after the plunger phase is established, thereby force-feeding a high pressure fuel to a common rail to start a rise in fuel pressure, and when a second solenoid control signal is outputted to force-feed a fuel to the common rail, a fuel injection valve has fuel pressure
22
b.
Thus, as shown in
FIG. 22
, even when the plunger shifts to a compression stroke via a bottom dead center from its stop position
22
a
during the time that elapsed before the determination of the plunger phase, th
Okamoto Takashi
Otani Asahiko
Shimada Kosaku
Yamada Hiroyuki
Gimie Mahmoud
Wolfe Willis R.
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